In 1951, based on the structures of  amino acids  and  peptides  and the planar nature of the  peptide bond , Pauling,  Robert Corey  and  Herman Branson  correctly proposed the  alpha helix  and  beta sheet  as the primary  structural motifs  in protein  secondary structure . [ 58 ] [ 59 ]  This work exemplified Pauling's ability to think unconventionally; central to the structure was the unorthodox assumption that one turn of the helix may well contain a non- integer  number of amino acid residues; for the alpha helix it is 3.7 amino acid residues per turn. [ citation needed ]


Pauling then proposed that  deoxyribonucleic acid  (DNA) was a  triple helix ; [ 60 ] [ 61 ]  his model contained several basic mistakes, including a proposal of neutral phosphate groups, an idea that conflicted with the acidity of DNA.  Sir Lawrence Bragg  had been disappointed that Pauling had won the race to find the alpha  helix structure  of proteins. Bragg's team had made a fundamental error in making their models of protein by not recognizing the planar nature of the peptide bond. When it was learned at the  Cavendish Laboratory  that Pauling was working on molecular models of the structure of DNA,  James Watson  and  Francis Crick  were allowed to make a molecular model of DNA. They later benefited from unpublished data from  Maurice Wilkins  and  Rosalind Franklin  at  King's College  which showed evidence for a helix and planar base stacking along the helix axis. Early in 1953 Watson and Crick proposed a correct structure for the DNA double helix. Pauling later cited several reasons to explain how he had been misled about the structure of DNA, among them misleading density data and the lack of high quality X-ray diffraction photographs. Pauling described this situation as "the biggest disappointment in his life". [ 62 ]


During the time Pauling was researching the problem, Rosalind Franklin in England was creating the world's best images. They were key to Watson's and Crick's success. Pauling did not see them before devising his mistaken DNA structure, although his assistant Robert Corey did see at least some of them, while taking Pauling's place at a summer 1952 protein conference in England. Pauling had been prevented from attending because his passport was withheld by the State Department on suspicion that he had Communist sympathies. This led to the legend that Pauling missed the structure of DNA because of the politics of the day (this was at the start of the  McCarthy  period in the United States). Politics did not play a critical role. Not only did Corey see the images at the time, but Pauling himself regained his passport within a few weeks and toured English laboratories well before writing his DNA paper. He had ample opportunity to visit Franklin's lab and see her work, but chose not to. [ 15 ] : 414–415   Despite these times, Pauling chose to move on from them and be thankful for the discoveries that he had already found. [ 62 ]


Pauling also studied  enzyme  reactions and was among the first to point out that enzymes bring about reactions by stabilizing the  transition state  of the reaction, a view which is central to understanding their mechanism of action. [ 63 ]  He was also among the first scientists to postulate that the binding of  antibodies  to antigens would be due to a complementarity between their structures. [ 64 ]  Along the same lines, with the physicist turned biologist  Max Delbrück , he wrote an early paper arguing that  DNA replication  was likely to be due to  complementarity , rather than similarity, as suggested by a few researchers. This was made clear in the model of the structure of DNA that Watson and Crick discovered. [ 65 ]


In November 1949, Pauling,  Harvey Itano ,  S. J. Singer  and Ibert Wells published " Sickle Cell Anemia, a Molecular Disease " [ 66 ]  in the journal  Science . It was the first proof of a human disease being caused by an abnormal protein, and  sickle cell anemia  became the first disease understood at the molecular level. (It was not, however, the first demonstration that variant forms of hemoglobin could be distinguished by electrophoresis, which had been shown several years earlier by  Maud Menten  and collaborators). [ 67 ]  Using  electrophoresis , they demonstrated that individuals with  sickle cell disease  have a modified form of hemoglobin in their  red blood cells , and that individuals with  sickle cell trait  have both the normal and abnormal forms of hemoglobin. This was the first demonstration causally linking an abnormal protein to a disease, and also the first demonstration that  Mendelian inheritance  determines the specific physical properties of proteins, not simply their presence or absence – the dawn of  molecular genetics . [ 68 ]


His success with sickle cell anemia led Pauling to speculate that a number of other diseases, including mental illnesses such as  schizophrenia , might result from flawed genetics. As chairman of the Division of Chemistry and Chemical Engineering and director of the Gates and Crellin Chemical Laboratories, he encouraged the hiring of researchers with a chemical-biomedical approach to mental illness, a direction not always popular with established  Caltech  chemists. [ 69 ] : 2


In 1951, Pauling gave a lecture entitled "Molecular Medicine". [ 70 ]  In the late 1950s, he studied the role of enzymes in brain function, believing that mental illness may be partly caused by enzyme dysfunction.  In the 1960s, as part of his interest in the effects of nuclear weapons, he investigated the role of mutations in evolution, proposing with his student Emile Zuckerkandl, the molecular evolutionary clock, the idea that mutations in proteins and DNA accumulate at a constant rate over time . [ 71 ]


On September 16, 1952, Pauling opened a new research notebook with the words "I have decided to attack the problem of the structure of nuclei." On October 15, 1965, Pauling published his Close-Packed Spheron Model of the atomic nucleus in two well respected journals,  Science  and the  Proceedings of the National Academy of Sciences . [ 72 ] [ 73 ]  For nearly three decades, until his death in 1994, Pauling published numerous papers on his spheron cluster model. [ 72 ] [ 74 ] [ 75 ] [ 76 ] [ 77 ] [ 78 ]


The basic idea behind Pauling's spheron model is that a nucleus can be viewed as a set of "clusters of nucleons". The basic nucleon clusters include the  deuteron  [np],  helion  [pnp], and  triton  [npn].  Even–even nuclei  are described as being composed of clusters of  alpha particles , as has often been done for light nuclei. [ 79 ]  Pauling attempted to derive the shell structure of nuclei from pure geometrical considerations related to  Platonic solids  rather than starting from an independent particle model as in the usual  shell model . In an interview given in 1990 Pauling commented on his model: [ 80 ]


Now recently, I have been trying to determine detailed structures of atomic nuclei by analyzing the ground state and excited state vibrational bends, as observed experimentally. From reading the physics literature, Physical Review Letters and other journals, I know that many physicists are interested in atomic nuclei, but none of them, so far as I have been able to discover, has been attacking the problem in the same way that I attack it. So I just move along at my own speed, making calculations ...


Pauling had been practically apolitical until  World War II . At the beginning of the  Manhattan Project , Robert Oppenheimer invited him to be in charge of the Chemistry division of the project. He declined, not wanting to uproot his family. [ 81 ]


Pauling did, however, work on research for the military. He was a principal investigator on 14  OSRD contracts . [ 82 ]   The  National Defense Research Committee  called a meeting on October 3, 1940, wanting an instrument that could reliably measure oxygen content in a mixture of gases, so that they could measure oxygen conditions in submarines and airplanes. In response Pauling designed the Pauling oxygen meter, which was developed and manufactured by  Arnold O. Beckman, Inc.  After the war, Beckman adapted the oxygen analyzers for use in incubators for premature babies. [ 83 ] : 180–186  [ 84 ]


In 1942, Pauling successfully submitted a proposal on "The Chemical Treatment of Protein Solutions in the Attempt to Find a Substitute for Human Serum for Transfusions". His project group, which included Joseph B. Koepfli and Dan H. Campbell, developed a possible replacement for  human blood plasma  in  transfusions :  polyoxy gelatin  (Oxypolygelatin). [ 85 ] [ 86 ]


Other wartime projects with more direct military applications included work on explosives, rocket propellants and the patent for an armor-piercing shell.  In October 1948, Pauling, along with  Lee A. DuBridge ,  William A. Fowler ,  Max Mason , and  Bruce H. Sage , was awarded a  Presidential Medal for Merit  by President  Harry S. Truman .  The citation credits him for his "imaginative mind", "brilliant success", and "exceptionally meritorious conduct in the performance of outstanding services". [ 87 ] [ 88 ] [ 89 ]   In 1949, he served as president of the  American Chemical Society . [ 90 ]


The aftermath of the  Manhattan Project  and his wife Ava's pacifism changed Pauling's life profoundly, and he became a peace activist. [ citation needed ]


In June 1945, a "May-Johnson Bill" began [ 91 ] [ 92 ] [ 93 ]  that would become the  Atomic Energy Act of 1946  (signed August 1, 1946). In November 1945, Pauling spoke to the  Independent Citizens Committee of the Arts, Sciences and Professions  (ICCASP) on  atomic weapons ; shortly after, wife Ava and he accepted membership. [ 94 ]   On January 21, 1946, the group met to discuss  academic freedom , during which Pauling said, "There is, of course, always a threat to academic freedom – as there is to the other aspects of the freedom and rights of the individual, in the continued attacks which are made on this freedom, these rights, by the selfish, the overly ambitious, the misguided, the unscrupulous, who seek to oppress the great body of mankind in order that they themselves may profit – and we must always be on the alert against this threat, and must fight it with vigor when it becomes dangerous." [ 94 ]


In 1946, he joined the  Emergency Committee of Atomic Scientists , chaired by  Albert Einstein . [ 95 ]  Its mission was to warn the public of the dangers associated with the development of nuclear weapons.


His political activism prompted the  US State Department  to deny him a passport in 1952, when he was invited to speak at a scientific conference in London. [ 96 ] [ 97 ]  In a speech before the  US Senate  on June 6 of the same year, Senator  Wayne Morse  publicly denounced the action of the State Department, and urged the Passport Division to reverse its decision. Pauling and his wife Ava were then issued a "limited passport" to attend the conference. [ 98 ] [ 99 ]  His full passport was restored in 1954, shortly before the ceremony in  Stockholm  where he received his first Nobel Prize. [ citation needed ]


Joining Einstein,  Bertrand Russell  and eight other leading scientists and intellectuals, he signed the  Russell-Einstein Manifesto  issued July 9, 1955. [ 100 ]  He also supported the  Mainau Declaration   of July 15, 1955, signed by 52 Nobel Prize laureates. [ 101 ]


In May 1957, working with   Washington University in St. Louis  professor  Barry Commoner , Pauling began to circulate a petition among scientists to stop nuclear testing. [ 102 ]   On January 15, 1958, Pauling and his wife presented a petition to United Nations Secretary General  Dag Hammarskjöld  calling for an end to  the testing of nuclear weapons .  It was signed by 11,021 scientists representing fifty countries. [ 103 ] [ 104 ]


In February 1958, Pauling participated in a publicly televised debate with the atomic physicist  Edward Teller  about the actual probability of fallout causing mutations. [ 105 ]   Later in 1958, Pauling published  No more war! , in which he not only called for an end to the testing of nuclear weapons but also an end to war itself. He proposed that a World Peace Research Organization be set up as part of the United Nations to "attack the problem of preserving the peace". [ 7 ]


Pauling also supported the work of the St. Louis Citizen's Committee for Nuclear Information (CNI). [ 102 ]  This group, headed by  Barry Commoner , Eric Reiss,  M. W. Friedlander and John Fowler, organized a longitudinal study to measure radioactive  strontium -90 in the  baby teeth  of children across North America.  The " Baby Tooth Survey ", published by  Louise Reiss , demonstrated conclusively in 1961 that above-ground nuclear testing posed significant public health risks in the form of  radioactive fallout  spread primarily via milk from cows that had ingested contaminated grass. [ 106 ] [ 107 ] [ 108 ]   The Committee for Nuclear Information is frequently credited for its significant contribution to supporting the test ban, [ 109 ]  as is the ground-breaking research conducted by Reiss and the "Baby Tooth Survey". [ 110 ]


Public pressure and the frightening results of the CNI research led to a moratorium on above-ground nuclear weapons testing, followed by the  Partial Test Ban Treaty , signed in 1963 by  John F. Kennedy  and  Nikita Khrushchev .  On the day that the treaty went into force, October 10, 1963, the Nobel Prize Committee awarded Pauling the  Nobel Peace Prize  for 1962.  (No prize had previously been awarded for that year.) [ 111 ]   They described him as "Linus Carl Pauling, who ever since 1946 has campaigned ceaselessly, not only against nuclear weapons tests, not only against the spread of these armaments, not only against their very use, but against all warfare as a means of solving international conflicts." [ 112 ]   Pauling himself acknowledged his wife Ava's deep involvement in peace work, and regretted that she was not awarded the Nobel Peace Prize with him. [ 113 ]


Many of Pauling's critics, including scientists who appreciated the contributions that he had made in chemistry, disagreed with his political positions and saw him as a naïve spokesman for  Soviet communism . In 1960, he was ordered to appear before the  Senate Internal Security Subcommittee , [ 114 ]  which termed him "the number one scientific name in virtually every major activity of the Communist peace offensive in this country". [ 115 ]  A headline in  Life  magazine characterized his 1962 Nobel Prize as "A Weird Insult from Norway". [ 116 ] [ 117 ]


Pauling was a frequent target of the  National Review  magazine. In an article entitled "The Collaborators" in the magazine's July 17, 1962, issue, Pauling was referred to not only as a collaborator, but as a "fellow traveler" of proponents of Soviet-style communism.  In 1963, Pauling sued the magazine, its publisher  William Rusher , and its editor  William F. Buckley, Jr  for $1 million. He lost both his libel suits and the 1968 appeal (unlike his earlier 1963 libel case against the  Hearst Corporation ), because in the meantime the landmark case  New York Times Co. v. Sullivan  had established the  actual malice  standard for libel lawsuits by public figures, requiring that not only falsehood but deliberate lying should be proved by the plaintiff in such cases. [ 118 ] [ 119 ] [ 120 ] [ 121 ]


His peace activism, his frequent travels, and his enthusiastic expansion into chemical-biomedical research all aroused opposition at Caltech. In 1958, the Caltech Board of Trustees demanded that Pauling step down as chairman of the Chemistry and Chemical Engineering Division. [ 69 ] : 2    Although he had retained tenure as a full professor, Pauling chose to resign from Caltech after he received the Nobel peace prize money. He spent the next three years at the  Center for the Study of Democratic Institutions  (1963–1967). [ 20 ]  In 1967, he moved to the University of California at San Diego, but remained there only briefly, leaving in 1969 in part because of political tensions with the Reagan-era board of regents. [ 69 ] : 3    From 1969 to 1974, he accepted a position as professor of chemistry at Stanford University. [ 34 ]


During the 1960s, President Lyndon Johnson's policy of increasing America's involvement in the Vietnam War caused an  anti-war movement  that the Paulings joined with enthusiasm. Pauling denounced the war as unnecessary and unconstitutional. He made speeches, signed protest letters and communicated personally with the North Vietnamese leader, Ho Chi Minh, and gave the lengthy written response to President Johnson. His efforts were ignored by the American government. [ 122 ]


Pauling was awarded the  International Lenin Peace Prize  by the USSR in 1970. [ 115 ] [ 123 ]   He continued his peace activism in the following years.  He and his wife Ava helped to found the  International League of Humanists  in 1974. [ 124 ]  He was president of the scientific advisory board of the  World Union for Protection of Life  and also one of the signatories of the  Dubrovnik–Philadelphia statement  of 1974/1976. [ 125 ]  Linus Carl Pauling was an honorary president and member of the International Academy of Science, Munich, until the end of his life. [ 126 ]


Pauling was also a supporter of the  Fair Play for Cuba Committee . [ 127 ]


He was one of the signatories of the agreement to convene a convention for drafting a  world constitution . [ 128 ] [ 129 ]  As a result, for the first time in human history, a  World Constituent Assembly  convened to draft and adopt a  Constitution for the Federation of Earth . [ 130 ]


Pauling supported a limited form of  eugenics  by suggesting that human carriers of defective genes be given a compulsory visible mark – such as a forehead tattoo – to discourage potential mates with the same defect, in order to reduce the number of babies with diseases such as  sickle cell anemia . [ 131 ] [ 132 ]


In 1941, at age 40, Pauling was diagnosed with  Bright's disease , a renal disease. Following the recommendations of  Thomas Addis , who actively recruited Ava Helen Pauling as "nutritionist, cook, and eventually as deputy 'doctor'", Pauling believed he was able to control the disease with Addis's then-unusual low-protein salt-free diet and vitamin supplements. [ 134 ]  Thus Pauling's initial – and intensely personal – exposure to the idea of treating disease with vitamin supplements was positive. [ citation needed ]


In 1965, Pauling read  Niacin Therapy in Psychiatry  by  Abram Hoffer  and theorized vitamins might have important biochemical effects unrelated to their prevention of associated deficiency diseases. [ 135 ]  In 1968, Pauling published a brief paper in  Science  entitled "Orthomolecular psychiatry", [ 136 ]  giving a name to the popular but controversial  megavitamin therapy  movement of the 1970s, and advocating that "orthomolecular therapy, the provision for the individual person of the optimum concentrations of important normal constituents of the brain, may be the preferred treatment for many mentally ill patients." Pauling coined the term "orthomolecular" to refer to the practice of varying the concentration of substances normally present in the body to prevent and treat disease. His ideas formed the basis of  orthomolecular medicine , which is not generally practiced by conventional medical professionals and has been strongly criticized. [ 137 ] [ 138 ]


In 1973, with  Arthur B. Robinson  and another colleague, Pauling founded the Institute of Orthomolecular Medicine in Menlo Park, California, which was soon renamed the  Linus Pauling Institute  of Science and Medicine. Pauling directed research on vitamin C, but also continued his theoretical work in chemistry and physics until his death. In his last years, he became especially interested in the possible role of vitamin C in preventing  atherosclerosis  and published three case reports on the use of  lysine  and vitamin C to relieve  angina pectoris . During the 1990s, Pauling put forward a comprehensive plan for the treatment of heart disease using lysine and vitamin C. In 1996, a website was created expounding Pauling's treatment which it referred to as Pauling Therapy. Proponents of Pauling Therapy believe that  heart disease can be treated and even cured using only lysine and Vitamin C and without drugs or heart operations. [ 139 ]


Pauling's work on  vitamin C  in his later years generated much controversy. He was first introduced to the concept of high-dose vitamin C by biochemist  Irwin Stone  in 1966. After becoming convinced of its worth, Pauling took 3 grams of vitamin C every day to prevent  colds . [ 13 ]  Excited by his own perceived results, he researched the clinical literature and published  Vitamin C and the Common Cold  in 1970. He began a long clinical collaboration with the British cancer surgeon  Ewan Cameron  in 1971 on the use of intravenous and oral vitamin C as cancer therapy for terminal patients. [ 140 ]  Cameron and Pauling wrote many technical papers and a popular book,  Cancer and Vitamin C , that discussed their observations. Pauling made vitamin C popular with the public [ 141 ]  and eventually published two studies of a group of 100 allegedly  terminal  patients that claimed vitamin C increased survival by as much as four times compared to untreated patients. [ 142 ] [ 143 ]


A re-evaluation of the claims in 1982 found that the patient groups were not actually comparable, with the vitamin C group being less sick on entry to the study, and judged to be "terminal" much earlier than the comparison group. [ 144 ]  Later clinical trials conducted by the  Mayo Clinic  led by oncologist  Dr. Edward T. Creagan  also concluded that high-dose (10,000 mg) vitamin C was no better than  placebo  at treating cancer and that there was no benefit to high-dose vitamin C. [ 145 ] [ 146 ] [ 147 ]  The failure of the clinical trials to demonstrate any benefit resulted in the conclusion that vitamin C was not effective in treating cancer; the medical establishment concluded that his claims that vitamin C could prevent colds or treat cancer were  quackery . [ 13 ] [ 148 ]  Pauling denounced the conclusions of these studies and handling of the final study as "fraud and deliberate misrepresentation", [ 149 ] [ 150 ]  and criticized the studies for using oral, rather than  intravenous  vitamin C [ 151 ]  (which was the dosing method used for the first ten days of Pauling's original study [ 148 ] ). Pauling also criticised the Mayo Clinic studies because the controls were taking vitamin C during the trial, and because the duration of the treatment with vitamin C was short; Pauling advocated continued high-dose vitamin C for the rest of the cancer patient's life whereas the Mayo Clinic patients in the second trial were treated with vitamin C for a median of 2.5 months. [ 152 ]


Ultimately the negative findings of the Mayo Clinic studies ended general interest in vitamin C as a treatment for cancer. [ 150 ]  Despite this, Pauling continued to promote vitamin C for treating cancer and the common cold, working with  The Institutes for the Achievement of Human Potential  to use vitamin C in the treatment of brain-injured children. [ 153 ]  He later collaborated with the Canadian physician  Abram Hoffer  on a micronutrient regime, including high-dose vitamin C, as adjunctive cancer therapy. [ 154 ]  A 2009 review also noted differences between the studies, such as the Mayo Clinic not using intravenous Vitamin C, and suggested further studies into the role of vitamin C when given intravenously. [ 155 ]   Results from most clinical trials suggest that modest vitamin C supplementation alone or with other nutrients offers no benefit in the prevention of cancer. [ 156 ] [ 157 ]


Pauling married  Ava Helen Miller  on June 17, 1923. The marriage lasted until her death in 1981. They had four children. [ 158 ]  Linus Carl Jr. (1925–2023) became a  psychiatrist ; [ 159 ]  Peter (1931–2003) a  crystallographer  at  University College London ; [ 160 ]  Edward Crellin (1937–1997) a  biologist ; [ 161 ]  and Linda Helen (born 1932) married noted Caltech geologist and glaciologist  Barclay Kamb . [ 162 ]


Pauling was raised as a member of the  Lutheran  Church, [ 163 ]  but later joined the  Unitarian Universalist  Church. [ 164 ]  Two years before his death, in a published dialogue with Buddhist philosopher  Daisaku Ikeda , Pauling publicly declared his  atheism . [ 165 ]


On January 30, 1960, Pauling and his wife were using a cabin about 80 miles (130 km) south of  Monterey , California, and he decided to go for a walk on a coastal trail.  He got lost and tried to climb the rocky cliff, but reached a large overhanging rock about 300 feet (90 m) above the ocean.  He decided it was safest to stay there, and meanwhile he was reported missing.  He spent a sleepless night on the cliff before being found after almost 24 hours. [ 166 ]


Pauling died of  prostate cancer  on August 19, 1994, at 19:20 at home in  Big Sur , California. [ 12 ]  He was 93 years old. [ 167 ]  A grave marker for Pauling was placed in Oswego Pioneer Cemetery in  Lake Oswego , Oregon by his sister Pauline, but Pauling's ashes, along with those of his wife, were not buried there until 2005. [ 168 ]


Pauling's discoveries led to decisive contributions in a  diverse array of areas including around 350 publications in the fields of quantum mechanics, inorganic chemistry, organic chemistry, protein structure, molecular biology, and medicine. [ 169 ] [ 170 ]


His work on chemical bonding marks him as one of the founders of modern  quantum chemistry . [ 9 ]   The Nature of the Chemical Bond  was the standard work for many years, [ 171 ]  and concepts like  hybridization  and  electronegativity  remain part of standard chemistry textbooks. While his  Valence bond  approach fell short of accounting quantitatively for some of the characteristics of molecules, such as the color of  organometallic  complexes, and would later be eclipsed by the  molecular orbital theory  of  Robert Mulliken , Valence Bond Theory still competes, in its modern form, with Molecular Orbital Theory and  density functional theory  (DFT) as a way of describing chemical phenomena. [ 172 ]  Pauling's work on crystal structure contributed significantly to the prediction and elucidation of the structures of complex minerals and compounds. [ 28 ] : 80–81   His discovery of the alpha helix and beta sheet is a fundamental foundation for the study of protein structure. [ 59 ]


Francis Crick  acknowledged Pauling as the "father of  molecular biology ". [ 9 ] [ 173 ]  His discovery of  sickle cell anemia  as a "molecular disease" opened the way toward examining genetically acquired mutations at a molecular level. [ 68 ]


Pauling's 1951 publication with Robert B. Corey and H. R. Branson, "The Structure of Proteins: Two Hydrogen-Bonded Helical Configurations of the Polypeptide Chain," was a key early finding in the then newly emerging field of molecular biology. This publication was honored by a Citation for Chemical Breakthrough Award from the Division of History of Chemistry of the American Chemical Society presented to the department of chemistry, Caltech, in 2017. [ 174 ] [ 175 ]


Oregon State University completed construction of the $77 million, 100,000-square-foot (9,300 m 2 ) Linus Pauling Science Center in the late 2000s, now housing the bulk of Oregon State's chemistry classrooms, labs, and instruments. [ 176 ]


On March 6, 2008, the  United States Postal Service  released a 41 cent stamp honoring Pauling designed by artist  Victor Stabin . [ 177 ] [ 178 ]  His description reads: "A remarkably versatile scientist, structural chemist Linus Pauling (1901–1994) won the 1954 Nobel Prize in Chemistry for determining the nature of the chemical bond linking atoms into molecules. His work in establishing the field of molecular biology; his studies of hemoglobin led to the classification of sickle cell anemia as a molecular disease." [ 68 ]  The other scientists on this sheet of stamps included  Gerty Cori , biochemist,  Edwin Hubble , astronomer, and  John Bardeen , physicist. [ 178 ]


California Governor  Arnold Schwarzenegger  and First Lady  Maria Shriver  announced on May 28, 2008, that Pauling would be inducted into the  California Hall of Fame , located at  The California Museum for History, Women and the Arts . The induction ceremony took place December 15, 2008. Pauling's son was asked to accept the honor in his place. [ 179 ]


By proclamation of Gov.  John Kitzhaber  in the state of Oregon, February 28 has been named "Linus Pauling Day". [ 180 ]   The Linus Pauling Institute still exists, but moved in 1996 from Palo Alto, California, to Corvallis, Oregon, where it is part of the Linus Pauling Science Center at  Oregon State University . [ 181 ] [ 182 ] [ 183 ]   The Valley Library  Special Collections at Oregon State University contain the Ava Helen and Linus Pauling Papers, including digitized versions of Pauling's forty-six research notebooks. [ 180 ]


In 1986, Caltech commemorated Linus Pauling with a symposium and lectureship. [ 184 ]  The Pauling Lecture series at Caltech began in 1989 with a lecture by Pauling himself.  The Caltech Chemistry Department renamed room 22 of Gates Hall the Linus Pauling Lecture Hall, since Pauling spent so much time there. [ 185 ]


Other places named after Pauling include Pauling Street in Foothill Ranch, California; [ 186 ]  Linus Pauling Drive in Hercules, California; Linus and Ava Helen Pauling Hall at  Soka University of America  in Aliso Viejo, California; [ 187 ]  Linus Pauling Middle School in Corvallis, Oregon; [ 188 ]  and  Pauling Field , a small airfield located in Condon, Oregon, where Pauling spent his youth. [ 189 ]   There is a psychedelic rock band in Houston, Texas, named  The Linus Pauling Quartet . [ 190 ]


The asteroid  4674 Pauling  in the inner asteroid belt, discovered by  Eleanor F. Helin , was named after Linus Pauling in 1991, on his 90th birthday. [ 191 ]


Linus Torvalds , developer of the  Linux  kernel, is named after Pauling. [ 192 ]


Nobel laureate  Peter Agre  has said that Linus Pauling inspired him. [ 193 ]


In 2010,  Pacific Northwest National Laboratory  named its distinguished postdoctoral program in his honor, as the Linus Pauling Distinguished Postdoctoral Fellowship Program. [ 194 ]


Pauling received numerous awards and honors during his career, including the following: [ 195 ] [ 34 ] [ 196 ]


The  phage group  (sometimes called the  American Phage Group ) was an informal network of biologists centered on  Max Delbrück  that contributed heavily to  bacterial genetics  and the  origins of molecular biology  in the mid-20th century.  The phage group takes its name from  bacteriophages , the bacteria-infecting  viruses  that the group used as experimental  model organisms . In addition to Delbrück, important scientists associated with the phage group include:  Salvador Luria ,  Alfred Hershey ,  Seymour Benzer ,  Charles Steinberg ,  Gunther Stent ,  James D. Watson ,  Frank Stahl , and  Renato Dulbecco .


Bacteriophages had been a subject of experimental investigation since  Félix d'Herelle  had isolated and developed methods for detecting and  culturing  them, beginning in 1917.  Delbrück, a physicist-turned biologist seeking the simplest possible experimental system to probe the fundamental laws of life, first encountered phages during a 1937 visit to  T. H. Morgan 's fly lab at  Caltech .  Delbrück was unimpressed with Morgan's experimentally complex model organism  Drosophila , but another researcher,  Emory Ellis , was working with the more elementary phage.  During the next few years, Ellis and Delbrück collaborated on methods of counting phage and tracking  growth curves ; they established the basic step-wise pattern of virus growth (the most obvious features of the  lytic cycle ). [ 1 ]


In a retrospective article, [ 2 ]   Emory Ellis  stated "Soon after  Max Delbruck  arrived at the Caltech Biology Division, intent on discovering how his background in physical sciences could be productively applied to biological problems, I showed him some step-growth curves.  His first comment was 'I don't believe it.'"  However, as Ellis describes, Delbruck soon dispelled this initial reaction of disbelief by his own analysis of the phenomenon, and promptly joined in the work with enthusiasm, bringing to it his training in mathematics and physics, and intense interest in genetics.  Their initial collaborative findings were published in 1939. [ 3 ]


The phage group started around 1940, after Delbrück and Luria had met at a physics conference.  Delbrück and  Salvador Luria  began a series of collaborative experiments on the patterns of infection for different strains of bacteria and bacteriophage.  They soon established the "mutual exclusion principle" that an individual bacterium can only be infected by one strain of phage.  In 1943, their "fluctuation test", later dubbed the  Luria–Delbrück experiment , showed that genetic  mutations  for phage resistance arise in the absence of  selection , rather than being a response to selection. [ 4 ] [ 5 ]   The traditional wisdom among bacteriologists prior to 1943 was that bacteria had no chromosomes and no genes.  The Luria–Delbrück experiment showed that bacteria, like other established model genetic organisms, have genes, and that these can spontaneously mutate to generate mutants that may then reproduce to form clonal lineages.  That year, they also began working with  Alfred Hershey , another phage experimenter. [ 6 ]   (The three would share the 1969  Nobel Prize in Physiology or Medicine , "for work on the replication mechanism and genetics of viruses".)


Hershey, [ 7 ]  described retrospectively the circumstances leading to the experiment using phage that he performed with his research assistant,  Martha Chase , in 1952, later known as the  Hershey–Chase experiment . [ 8 ]   This experiment provided key evidence that DNA, as distinct from protein, is the genetic material of the phage and therefore the likely genetic material generally.


In 1946, Luria made a finding that was destined to open up a new insight on how the stability of DNA is achieved (see Luria, [ 5 ]  pg. 96).  What he discovered was that when, after UV irradiation, two or more "dead" phage entered the same bacterial cell, they often became alive again and produced normal live progeny. [ 9 ]   This was the first example of reactivation of cells or organisms that had been damaged by radiation.  He interpreted the reactivation, correctly, as a result of genetic recombination (see also  homologous recombination ).   James Watson  (future co-discover of the Watson–Crick structure of DNA in 1953, and winner of the Nobel Prize, 1962), was Luria's first graduate student at the Indiana University.  As his PhD thesis project, Watson showed that X-rayed phage can participate in  genetic recombination  and  multiplicity reactivation .


As remembered by Luria (1984, [ 5 ]  pg. 97) the discovery of reactivation of irradiated phage (referred to as " multiplicity reactivation ") immediately started a flurry of activity in the study of repair of radiation damage within the early phage group (reviewed by Bernstein [ 10 ]  in 1981).  It turned out later that the repair of damaged phage by mutual help that Luria had discovered was only one special case of DNA repair.  Cells of all types, not just, bacteria and their viruses, but all organisms studied, including humans, are now known to have complex biochemical processes for repairing DNA damages (see  DNA repair ).  DNA repair processes are also now recognized as playing critical roles in protecting against aging, cancer, and infertility.


Jim Watson , in a retrospective article, [ 11 ]  described his first experiences as a student with Luria in 1947.  Apparently, according to Watson "…many students were afraid of Luria who had a reputation of being arrogant toward people who were wrong."  However, as the fall term wore on, Watson "saw no evidence of the rumored inconsiderateness toward dimwits."  Thus with no real reservations (except for occasional fear that he was not bright enough to move in his circle) he asked Luria whether he could do research under his direction in the spring term. Luria promptly said yes, and gave Watson the task of studying X-ray-induced  multiplicity reactivation  of phage as described above.  The only other scientist in Luria's lab at that time, with whom Watson shared a lab bench, was  Renato Dulbecco  (a future member of the phage group), who had recently arrived from Italy to do experiments on phage multiplicity reactivation.  Later that semester (1948), Watson met, for the first time, Delbruck who was briefly visiting Luria. Watson [ 11 ]  wrote "Almost from Delbruck's first sentence, I knew I was not going to be disappointed.  He did not beat around the bush and the intent of his words was always clear.  But even more important to me was his youthful appearance and spirit."  Watson noted that on this occasion, as on many subsequent occasions, Delbruck talked about  Bohr  (the physicist) and his belief that a complementarity principle, perhaps like that needed for understanding quantum mechanics, would be the key to the real understanding of biology.


In 1950, Renato Dulbecco now at Caltech with Delbrück, worked out a procedure for assaying animal virus particles by their formation of plaques on a sheet of cultured cells, just as phage form plaques on a lawn of bacterial cells.  This procedure set the stage for Dulbecco to implement a comprehensive research program for quantitative studies on animal viruses to fathom their intracellular reproductive cycle.  This work was recognized by award of the Nobel Prize in 1975. [ 12 ]


After the discovery of the structure of DNA in 1953, it was still unclear how DNA replicated. The favored model at the time was semi-conservative replication, but experimental proof was needed. The  Meselson–Stahl experiment , [ 13 ]  performed by  Matthew Meselson  and  Franklin Stahl  in 1958, was the key experiment that provided convincing evidence of semi-conservative replication, the mechanism now known to be correct.  Meselson and Stahl described the circumstances leading to this key experiment. [ 14 ]   It has since been described as the "Most Beautiful Experiment in Biology". [ 15 ]   Its beauty is tied to the simplicity of the result, although the route that led to the experiment was far from simple.


As described in a retrospective article, [ 16 ]   Seymour Benzer  joined Delbrück's phage group at Caltech in 1949 as a postdoctoral fellow.  There he shared a lab room with  Jean Weigle  where they did collaborative experiments on phage T4.  Upon leaving Caltech, Benzer continued experiments on phage T4 at the Pasteur Institute in Paris and then Purdue University where he developed a system for studying the fine structure of the gene using mutants defective in the rIIA and rIIB genes. [ 17 ] [ 18 ]   These genetic experiments, involving crosses of rII mutants, led to the finding of a unique linear order of mutational sites within the genes.  This result provided strong evidence for the key idea that the gene has a linear structure equivalent to a length of DNA with many sites that can independently mutate.


In 1952,  Salvador Luria  had discovered the phenomenon of "restriction-modification" (the modification of phage growing within an infected bacterium, so that upon their release and re-infection of a related bacterium the phage's growth is restricted) (described by Luria, [ 5 ]  pgs. 45 and 99).  Weigle, working with Giuseppe Bertani and  Werner Arber , soon clarified the basis for this phenomenon.  They showed that restriction was actually due to attack by specific bacterial enzymes on the modified phage's DNA.  This work led to the discovery of the class of enzymes now known as " restriction enzymes ". These enzymes allowed controlled manipulation of DNA in the laboratory, thus providing the foundation for the development of genetic engineering.


Weigle also demonstrated the inducible nature of DNA damage-response genes in bacteria, a phenomenon that has come to be known as the  SOS response .  This response includes DNA damage-inducible mutagenesis (termed Weigle mutagenesis in his honor) and inducible repair following DNA damage (termed Weigle reactivation).


In 1961,  Sydney Brenner , an early member of the phage group, collaborated with Francis Crick, Leslie Barnett and Richard Watts-Tobin at the Cavendish Laboratory in Cambridge to perform genetic experiments that demonstrated the basic nature of the genetic code for proteins. [ 19 ]   These experiments, carried out with mutants of the rIIB gene of phage T4, showed, that for a gene that encodes a protein, three sequential bases of the gene's DNA specify each successive amino acid of the protein.  Thus the genetic code is a triplet code, where each triplet (called a codon) specifies a particular amino acid.  They also obtained evidence that the codons do not overlap with each other in the DNA sequence encoding a protein, and that such a sequence is read from a fixed starting point.


Gunther Stent  joined the phage group in 1948 after taking their phage course at Cold Spring Harbor, New York.  The ongoing informal discussions among these workers on the progress of their research led to a book by Stent entitled  Molecular Biology of Bacterial Viruses  (dedicated to Max Delbrück) [ 20 ]  which was a lucid account of the accomplishments in this emerging field up to 1963.  Later, in his memoirs, Stent (1998) described some of the activities and personal interactions that illustrated the unique intellectual spirit of the phage group during its early crucial years (1948-1950). [ 21 ]


Delbrück, through his charm and enthusiasm, brought many biologists (and physicists) into phage research in the early 1940s (see: Charles Steinberg ).  [ 22 ]   In 1944, Delbrück promoted the "Phage Treaty", a call for phage researchers to focus on a limited number of phage and bacterial strains, with standardized experimental conditions.  This helped to make research from different laboratories more easily comparable and replicable, helping to unify the field of  bacterial genetics . [ 23 ]


Apart from direct collaborations, the main legacy of the phage group resulted from the yearly summer phage course taught at  Cold Spring Harbor Laboratory  and taught sporadically at Caltech.  Beginning in 1945, Delbrück and others taught young biologists the fundamentals of phage biology and experimentation, instilling the phage group's distinctive math- and physics-oriented approach to biology.  Many of the leaders of the emerging field of  molecular biology  were alumni of the phage course, which continued to be taught through the 1950s and 1960s. [ 24 ] [ 25 ]


In 1995, Millard Susman published a retrospective article on the phage course as it was given over the years (1945 – 1970) both at Cold Spring Harbor (New York) and at the California Institute of Technology. [ 26 ]   The article lists many of the graduates of the course, describes some of their accomplishments, and provides interesting anecdotes related to the course.   Richard Feynman , the distinguished Caltech theoretical physicist, learned how to work with phage during the summer of 1961 with the help of  Charles M. Steinberg , and his experimental results were included in a publication by Edgar et al. [ 27 ]


The isolation of conditional lethal mutants of phage during 1962-1964 by the phage group members provided an opportunity to study the function of virtually all of the genes that are essential for growth of the phage under laboratory conditions. [ 28 ] [ 29 ]   One class of conditional lethal mutants is known as  amber mutants . [ 30 ]   These mutants were isolated and genetically characterized by Richard Epstein, Antoinette Bolle and  Charles M. Steinberg [ 31 ]  in 1962 (although publication of their initial findings was delayed for 50 years: see Epstein et al., 2012. [ 32 ] ).  A more complete genetic characterization of the amber mutants was described by Epstein et al. in 1964. [ 33 ]   Another class of conditional lethal mutants, referred to as temperature-sensitive mutants, was obtained by Robert Edgar and Ilga Lielausis. [ 34 ]   Studies of these two classes of mutants led to considerable insight into numerous fundamental biologic problems.  Thus understanding was gained on the functions and interactions of the proteins employed in the machinery of DNA replication, repair and recombination, and on how viruses are assembled from protein and nucleic acid components (molecular morphogenesis).  Furthermore, the role of chain terminating codons was elucidated.  One noteworthy study was performed by Sydney Brenner and collaborators using amber mutants defective in the gene encoding the major head protein of phage T4. [ 35 ]   This experiment provided strong evidence for the widely held, but prior to 1964 still unproven, "sequence hypothesis" that the amino acid sequence of a protein is specified by the nucleotide sequence of the gene determining the protein.  Thus, this study demonstrated the co-linearity of the gene with its encoded polypeptide.


Photo 51  is an  X-ray  based  fiber diffraction  image of a  paracrystalline  gel composed of  DNA  fiber [ 1 ]  taken by  Raymond Gosling , [ 2 ] [ 3 ]  a postgraduate student working under the supervision of  Maurice Wilkins  and  Rosalind Franklin  at  King's College London , while working in  Sir John Randall 's group. [ 4 ] [ 5 ] [ 6 ] [ 7 ] [ 8 ]  The image was tagged "photo 51" because it was the 51st diffraction photograph that Franklin had taken. [ 9 ]  It was critical evidence [ 10 ]  in identifying the structure of DNA. [ 11 ]


According to a later account by  Raymond Gosling , although  Photo 51  was an exceptionally clear diffraction pattern of the "B" form of DNA, Franklin was more interested in solving the diffraction pattern of the "A" form of DNA, so she put Gosling's  Photo 51  to the side. When it had been decided that Franklin would leave King's College, Gosling showed the photograph to  Maurice Wilkins [ 12 ] [ 13 ]  (who would become Gosling's advisor after Franklin left).


A few days later, Wilkins showed the photo to  James Watson  after Gosling had returned to working under Wilkins' supervision. Franklin did not know this at the time because she was leaving  King's College London . Randall, the head of the group, had asked Gosling to share all his data with Wilkins. [ 5 ]  Watson recognized the pattern as a helix because his co-worker  Francis Crick  had previously published a paper of what the diffraction pattern of a helix would be. [ 12 ]  Watson and Crick used characteristics and features of  Photo 51 , together with evidence from multiple other sources, to develop the chemical model of the DNA molecule. Their model, along with papers by Wilkins and colleagues, and by Gosling and Franklin, were first published, together, in 1953, in the same issue of  Nature .


In 1962, the  Nobel Prize  in Physiology or Medicine was awarded to Watson, Crick and Wilkins. The prize was not awarded to Franklin; she had died four years earlier, and although there was not yet a rule against posthumous awards, [ 14 ]  the Nobel Committee generally does not make posthumous nominations. [ 15 ]  Gosling's work also was not cited by the prize committee.


The photograph provided key information that was essential for developing a model of DNA. [ 11 ] [ 16 ]  The diffraction pattern determined the helical nature of the double helix strands ( antiparallel ). The outside of the DNA chain has a backbone of alternating deoxyribose and phosphate moieties, and the base pairs, the order of which provides codes for protein building and thereby inheritance, are inside the helix. Watson and Crick's calculations from Gosling and Franklin's photography gave crucial parameters for the size and structure of the helix. [ 16 ]


Photo 51  became a crucial data source [ 17 ]  that led to the development of the DNA model and confirmed the prior postulated  double helical  structure of DNA, which were presented in the series of three articles in the journal  Nature  in 1953.


As historians of science have re-examined the period during which this image was obtained, considerable controversy has arisen over both the significance of the contribution of this image to the work of Watson and Crick, as well as the methods by which they obtained the image. Franklin had been hired independently of Maurice Wilkins, who, taking over as Gosling's new supervisor, showed  Photo 51  to Watson and Crick without Franklin's knowledge. Whether Franklin would have deduced the structure of DNA on her own, from her own data, had Watson and Crick not obtained Gosling's image, is a hotly debated topic, [ 11 ] [ 16 ] [ 18 ] [ 19 ]  made more controversial by the negative caricature of Franklin presented in the early chapters of  Watson's history of the research on DNA structure,  The Double Helix . [ 16 ] [ 20 ] [ 21 ]   Watson admitted his distortion of Franklin in his book, noting in the epilogue: "Since my initial impressions about [Franklin], both scientific and personal (as recorded in the early pages of this book) were often wrong, I want to say something here about her achievements." [ 22 ]


Photograph 51  is a  play  by  Anna Ziegler .  Photograph 51  opened in the  West End of London  in September 2015. [ 1 ]  The play focuses on the often-overlooked role of  X-ray crystallographer   Rosalind Franklin  in the discovery of the double helix structure of  DNA  while working at  King's College London . [ 2 ] [ 3 ]  This play won the third  STAGE  International Script Competition in 2008. [ 4 ]  The title comes from  Photo 51 , the nickname given to an X-ray diffraction image taken by Raymond Gosling in May, 1952, under the supervision of Rosalind Franklin. [ 5 ]  The one-act play runs for 95 minutes with no intermission.


Photograph 51  was commissioned, developed, and given its world premiere under the direction of Mary Resing by Active Cultures Theatre in Maryland in 2008.  That year, it also won the 2008 STAGE (Scientists, Technologists and Artists Generating Exploration) International script competition for Best New Play.   Photograph 51  had subsequent productions at The Fountain Theatre in Los Angeles,  Ensemble Studio Theatre  in New York,  Theater J  in Washington DC,  Seattle Repertory Theatre  in Seattle, amongst many others, [ 6 ]  then in London's  Noël Coward Theatre , in the  West End , directed by  Michael Grandage . [ 7 ]  The play premiered in Australia in Melbourne in 2019. [ 8 ]


The original cast of the London play: [ 9 ]


Michael Billington  of  The Guardian  wrote that "Nicole Kidman captures the ecstasy of scientific discovery".... "Anna Ziegler's new play asserts the contribution of 1950s chemist Rosalind Franklin to the discovery of DNA and asks: is science still sexist?." [ 10 ]


Ben Brantley  of  The New York Times  wrote that "When Nicole Kidman steps out of the shadows, breaking off from a wall of men, and onto the edge of the stage at the Noël Coward Theatre...her eyes beam undiluted willpower. It is a gaze that both chills and warms, radiating and demanding trust in this singularly self-possessed presence..... Yes, the script makes its concessions to romantic conventions....  Photograph 51  sustains crisp dramatic tension even when it skirts banality or expository tedium. And Ms Kidman, who turns Franklin's guardedness into as much a revelation as a concealment of character, is pretty close to perfection." [ 11 ]


Paul Taylor  of  The Independent  wrote that "In her compelling and subtle performance, Kidman beautifully captures the prickly defensiveness, the lonely dedication, and the suppressed emotional longings of the scientist.... Michael Grandage's superb 91-minute production expertly balances its energies as detective thriller and as interactive speculation about the hovering moments where her life could have taken a different turning." [ 12 ]


Stephen Dalton  of  The Hollywood Reporter  wrote that "...Ziegler's play is essentially a middling blend of straight bio-drama and high-school science lesson. Without Kidman's marquee appeal, it would have been an unusually dowdy choice for the West End. Fortunately, Kidman delivers." "[H]er performance is muted but reliably intense, hinting at wounded depths beneath Franklin's implacably chilly exterior....Grandage's production is a worthy effort, but a little passionless, inherently limited in dramatic force by its subject matter." [ 13 ]


Dominic Cavendish of  The Daily Telegraph  gave the play four out of five stars, writing that "...Kidman brilliantly suggests an intelligent woman compacted of porcelain and steel. Being no-nonsense, she's often funny. An early put-down – 'I don't joke' – gets a laugh but lays bare her peculiarity too." and "Although the supporting male performances suffer from scantily written roles, Grandage directs it all with characteristically fluid aplomb, placing the action (sometimes using neat, quasi-scientific symmetries) amid a towering set by Christopher Oram that evokes the bombed-out Palladian magnificence of King's, piles of rubble lapping at arches. The effect is part bunker, part grand signifier of civilisation and the building blocks of life, and part tomb too. Neil Austin's forensic lighting, cutting through clouds of haze, sees to it that as Edward Bennett and Will Attenborough's Crick and Watson finally unravel a secret held from mankind for millennia, all hint of rosiness in Rosalind's face vanishes, a deathly pallor taking its stead. Can one image tell us almost everything? Yes, it can. A triumph." [ 14 ]


Henry Hitchings  of  Evening Standard  gave the play four out of five stars, writing that "This isn't an obvious star vehicle, and there's certainly plenty for those around Kidman to get their teeth into in Michael Grandage's smartly paced production. Edward Bennett and Will Attenborough combine vigorously as Francis Crick and James Watson, whose names are today synonymous with scientific sleuthing, and Stephen Campbell Moore brings just the right degree of donnish clumsiness to Maurice Wilkins, who shared their Nobel Prize in 1962 (four years after Franklin's untimely death). Only the American researcher Don Caspar (the excellent Patrick Kennedy) seems capable of treating her as a person rather than an obstacle. Still, it's Kidman's finely poised performance that underpins this vision of intensely entwined but separate lives. She captures the obsessive nature of a woman dismissed by Watson as being “sticky” and having an “acid smile”, while suggesting the complexity beneath her severe façade – an inspiring mix of passion, pride and vulnerability." [ 15 ]


Ian Shuttleworth  of  FT  wrote that "Kidman was last seen on the London stage in David Hare's  The Blue Room  in 1998. This time her kit remains on, and dowdy: Franklin has eyes only for her X-ray crystallography work on DNA at King's College, London, without which Crick and Watson over in Cambridge would almost certainly not have cracked the secret of the double helix. In Michael Grandage's production, Kidman manages to animate the cold fish Franklin; her features are fluidly though not hugely mobile." [ 16 ]


Michael Arditti  of  Express  gave it four stars, commenting that Rosalind Franklin refused to elicit sympathy from her colleagues, and it is to Kidman's credit that she refuses to elicit it from her audience. Like her character, she focuses on the intellectual, which makes her two moments of self-revelation all the more powerful.". [ 17 ]


Reginald Crundall Punnett   FRS  ( / ˈ p ʌ n ɪ t / ; 20 June 1875 – 3 January 1967) [ 1 ] [ 2 ] [ 3 ] [ 4 ] [ 5 ]  was a British  geneticist  who co-founded, with  William Bateson , the  Journal of Genetics  in 1910.  Punnett is probably best remembered today as the creator of the  Punnett square , a tool still used by  biologists  to predict the  probability  of possible  genotypes  of offspring.  His  Mendelism  (1905) is sometimes said to have been the first textbook on genetics; it was probably the first  popular science  book to introduce genetics to the public.


Reginald Punnett was born in 1875 in the town of Tonbridge in Kent, England.  While recovering from a childhood bout of appendicitis, Punnett became acquainted with  Jardine's  Naturalist's Library and developed an interest in natural history. Punnett was educated at  Clifton College . [ 6 ]


Attending  Gonville and Caius College, Cambridge , Punnett earned a bachelor's degree in zoology in 1898 and a master's degree in 1901. [ 7 ]  Between these degrees he worked as a demonstrator and part-time lecturer at the  University of St. Andrews'  Natural History Department.  In October 1901, Punnett was back at Cambridge when he was elected to a  Fellowship  at Gonville and Caius College, [ 8 ]  working in zoology, primarily the study of worms, specifically  nemerteans .  It was during this time that he and  William Bateson  began a research collaboration, which lasted several years. [ 9 ]


When Punnett was an undergraduate,  Gregor Mendel's  work on inheritance was largely unknown and unappreciated by scientists.  However, in 1900, Mendel's work was rediscovered by  Carl Correns ,  Erich Tschermak von Seysenegg  and  Hugo de Vries .  William Bateson became a proponent of  Mendelian genetics  and had Mendel's work translated into English.  It was with Bateson that Reginald Punnett helped establish the new science of genetics at Cambridge.  He, Bateson and  Saunders  co-discovered  genetic linkage  through experiments with chickens and sweet peas. [ 10 ]


In 1905 Punnett devised what is now called the  Punnett square , a square diagram that is used to predict the genotypes of a particular cross or breeding experiment, described for the first time [ 11 ]  in the 2nd edition of his book. [ 12 ]


In 1908, unable to explain how a dominant allele would not become fixed and ubiquitous in a population, Punnett introduced one of his problems to the mathematician  G. H. Hardy , with whom he played  cricket . Hardy went on to formulate the  Hardy–Weinberg principle , independently of the German  Wilhelm Weinberg . Punnett was Superintendent of the  Cambridge University Museum of Zoology  from 1908 to 1909. [ 13 ]


In 1909 he went to  Sri Lanka  to meet Arthur Willey, FRS, then Director of the  Colombo Museum  and  R H Lock , then Scientific Assistant at the  Peradeniya Botanical Gardens  and to catch butterflies. The following year, he published a monograph, '"Mimicry" in Ceylon Butterflies, with a suggestion as to the nature of Polymorphism', in  Spolia Zeylanica , the journal of the Colombo Museum, [ 14 ]  in which he voiced his opposition to  gradualistic  accounts of the evolution of mimicry which he later expanded on, in his 1915 book  Mimicry in Butterflies .


In 1910 Punnett became a professor of biology at Cambridge, and then the first  Arthur Balfour Professor of Genetics  when Bateson left in 1912. [ 15 ]  In the same year, Punnett was elected a  Fellow  of the  Royal Society . He received the society's  Darwin Medal  in 1922.


During World War I, Punnett successfully applied his expertise to the problem of the early determination of sex in  chickens . Since only females were used for egg-production, early identification of male chicks, which were destroyed or separated for fattening, meant that limited animal-feed and other resources could be used more efficiently.  Punnett's work in this area was summarized in  Heredity in Poultry  (1923). With  Michael Pease  as his assistant, he created the first  auto-sexing  chicken breed, the Cambar, by transferring the barring gene of the  Barred Rock  to the  Golden Campine . [ 16 ]


Reginald Punnett retired in 1940, and died at the age of 91 in 1967 in  Bilbrook ,  Somerset .


The  Randall Division of Cell and Molecular Biophysics  (the  Randall ) is a research institute of  King's College London  located in  London   United Kingdom . It is a centre for study in  allergy  and  asthma ;  muscle  signalling and development; structural biology; muscle biophysics;  cell   motility  and  cytoskeleton , and cell imaging.


The Randall continues the tradition of Biophysics at King's established by  Sir John Randall , which produced the studies of the structure of  DNA  by  Rosalind Franklin  and  Maurice Wilkins . Much of this early work was supported by the  Medical Research Council , who still provide the majority of research funding.


The Biophysics Unit expanded and in the 1960s moved to the site in Drury Lane that later became known as the Randall Institute, incorporating at various stages the King's Biophysics Department, MRC Cell Biophysics Unit, and MRC Muscle and Motility Unit. After King's merged with the Guy's and St Thomas’ Medical Schools in 1998, the Randall Institute research groups moved to new labs on the Guy's Campus at London Bridge, which became the present Randall Division of Cell and Molecular Biophysics. [ 1 ]


Rosalind Franklin and DNA  is a biography of an English chemist  Rosalind Franklin  (1920–1958) written by her American friend  Anne Sayre  in 1975. Franklin was a physical chemist who made pivotal research in the  discovery of the structure of DNA , known as "the most important discovery" in biology. [ 1 ] [ 2 ]  DNA itself had become "life's most famous molecule". [ 3 ]  While working at the  King's College London  in 1951, she discovered two types of DNA called  A-DNA  and  B-DNA . Her  X-ray images  of DNA indicated  helical structure . Her X-ray image of B-DNA (called  Photo 51 ) taken in 1952 became the best evidence for the structure of DNA. For the discovery of the correct chemical structure of DNA, the  Nobel Prize in Physiology or Medicine  1962 was shared by her colleagues and close researchers  James Watson ,  Francis Crick  and  Maurice Wilkins ; she had died four years earlier in 1958 making her ineligible for the award. [ 4 ] [ 5 ]


Rosalind Franklin joined King's College London in January 1951 to work on the crystallography of DNA. By the end of that year, she established two important facts: one is that phosphate groups, which are the molecular backbone for the nucleotide chains, lie on the outside (it was a general consensus at the time that they were at the inside); and the other is that DNA exists in two forms, a crystalline (dry form) A-DNA and a hydrated (wet form) B-DNA. With her PhD student Raymond Gosling, she produced a series of X-ray images of DNA. The photograph (number 51, hence, popularised as Photo 51) of B-DNA taken in May 1952 was especially crucial.  X-ray crystallography  did not immediately show the precise helical structure. Franklin chose to work on A-DNA, while B-DNA was given to Maurice Wilkins. By the early 1953, Franklin was aware that both A and B forms of DNA were composed of two helical chains. [ 6 ]  By then, James Watson and Francis Crick at Cambridge University had built a correct double helical model of DNA, based on her experimental data. [ 4 ]


The discovery of the structure of DNA in 1953 is regarded as "the greatest and most important scientific discovery of the 20th Century". Francis Crick, James Watson and Maurice Wilkins received the  Nobel Prize in Physiology or Medicine  in 1962 for the discovery. [ 5 ]  This discovery laid the foundation for modern biology, including medical and molecular research. The discoverers earned lasting worldwide fame. But the contribution made by Rosalind Franklin, who died in 1958, was largely forgotten. [ 4 ]  The main motive for Sayre's book came from James Watson's memoir  The Double Helix : A Personal Account of the Discovery of the Structure of DNA . Published in 1968,  The Double Helix  reflected the account of the discovery in which Franklin was portrayed as  "uninteresting", "belligerent", and "sharp, stubborn mind", referring her as "Rosy", the name she did not want to be called. Watson described her as having "all the imagination of English blue-stocking adolescents", and "the product of an unsatisfied mother". [ 7 ]


As a close friend of Franklin, Sayre realised that Watson's portrayal of Franklin was negative and referred to it as an "every known prejudice against intellectual women". [ 8 ]  She set a project for writing about Franklin's life and contribution to science. After researching for five years, she published the book in 1975, which she claimed was not a biography, but a protest to Watson's account. [ 9 ]  It is these two books which brought Franklin to fame. [ 10 ]


Sayre first met Franklin in 1949 at Laboratoire Central des Services Chimiques de l'État in Paris, where Franklin and her husband were post-doctoral researchers. [ 11 ]  They frequently met in England after Franklin moved there. In the US also, Franklin visited her several times upon attending scientific conferences. They regularly exchanged letters. Sayre was particularly important during the last days of Franklin. Franklin developed  ovarian cancer  in 1957 and underwent surgical operation in London. Sayre stayed with Franklin at the hospital and looked after Franklin's apartment. After Franklin's discharge from hospital, she nursed her in a rented cottage for some days. Back in New York in October, Sayre received a letter from Franklin stating that Franklin was to visit her on the way to a conference at  Bloomington, Indiana . They never met—Franklin's condition deteriorated and she died on 16 April 1958. [ 12 ]


Sayre's book gave Franklin an important place in the history of science, as a major contributor to the discovery of the structure of DNA. However, the book is written from a strong  feminist  standpoint, portraying Franklin as an icon of the movement, and allegedly misrepresenting the nature of  sexism  at the time. [ 13 ] [ 14 ]


Sayre claimed that "in 1951 ... King's College as an institution, was not distinguished for the welcome that it offered to women ... Rosalind ... was unused to  purdah  [a religious and social institution of female seclusion] ... there was one other woman scientist on the laboratory staff". [ 15 ]  However, Farooq Hussain has noted that "there were seven women in the biophysics department ...  Jean Hanson  became an FRS,  Dame Honor B. Fell , Director of  Strangeways Laboratory , supervised the biologists". [ 16 ]  Another Franklin biographer,  Brenda Maddox , agrees, declaring: " Randall  ... did have many women on his staff ... they found him ... sympathetic and helpful." [ 17 ]


Sayre also said that "while the male staff at King's lunched in a large, comfortable, rather clubby dining room" the female staff of all ranks "lunched in the student's hall or away from the premises". [ 18 ]  However, Lynne Osman Elkin has asserted that most of the  MRC  group (including Franklin) typically ate lunch together in the mixed dining room discussed below. [ 19 ]  Maddox has concurred, asserting that Randall "liked to see his flock, men and women, come together for morning coffee, and at lunch in the joint dining room, where he ate with them nearly every day." [ 20 ]  Francis Crick also remarked that "her colleagues treated men and women scientists alike." [ 21 ]


Sayre also claimed that Franklin's father, Ellis, objected to his daughter's higher education. [ 22 ]  That has led to accusations of sexism in Ellis Franklin's attitude to Rosalind, as well as the allegation that he strongly opposed her entering Newnham College. [ 23 ] [ 24 ] [ 25 ]  Her sister, Jenifer Glynn, has maintained that those stories are myths, and that her parents fully supported Franklin's entire career. [ 26 ]


Glynn has accused Sayre of making her sister a feminist heroine, [ 27 ]  and called  Rosalind Franklin and DNA  "the start of what has become something of a 'Rosalind Industry'." She has argued that declaring Franklin to be a feminist symbol would have "embarrassed her [Rosalind Franklin] almost as much as Watson's account would have upset her", [ 26 ]  and maintains that her sister "was never a feminist." [ 28 ]  Crick, and Franklin's close friend  Aaron Klug , have agreed that Franklin was definitely not a feminist. [ 29 ]


Rosalind Franklin: The Dark Lady of DNA  is a biography of  Rosalind Franklin , a scientist whose work helped discover the structure of DNA. [ 1 ] [ 2 ]   It was written by  Brenda Maddox  and published by  HarperCollins  in October 2002. [ 3 ]


A play based in part on the book,  Photograph 51  written by  Anna Ziegler , was staged in London in 2015 starring  Nicole Kidman . [ 4 ]


The book received the 2002  Los Angeles Times Book Prize  for Science and Technology. [ 5 ]  It was also awarded the  Marsh Biography Award  in 2003, and was shortlisted for the 2002  Whitbread Biography Award . [ 6 ]


This article about a biographical or autobiographical book on  scientists  is a  stub . You can help Wikipedia by  expanding it .


Edith Rebecca Saunders   FLS  (14 October 1865 – 6 June 1945) was a British  geneticist  and  plant anatomist . Described by  J. B. S. Haldane  as the "Mother of British Plant Genetics", [ 1 ]  she played an active role in the  re-discovery of Mendel's laws of heredity , the understanding of trait inheritance in plants, and was the first collaborator of the geneticist  William Bateson . She also developed extensive work on flower anatomy, particularly focusing on the  gynoecia , the female reproductive organs of flowers.


Saunders was born on 14 October 1865 in  Brighton , England. She was educated first at Handsworth Ladies' College and in 1884 she entered the female-only  Newnham College, Cambridge . [ 2 ]  There, she attended both Part I (in 1887) and II (in 1888) of the  Natural Sciences Tripos .


She continued to post-graduate research, and served as a demonstrator at the  Balfour Biological Laboratory for Women  between 1888 and 1890 (where students from  Newnham  and  Girton  colleges received preparation for the Natural Sciences Tripos). She was the last director of that Laboratory between 1890 and 1914. [ 3 ]
She was also director of studies at Girton College (1904–1914) and Newnham College (1918–1925). [ 4 ]


She was appointed a fellow of the  Royal Horticultural Society  from which she received the  Banksian Medal  in 1906. In 1905 she was elected a Fellow of the  Linnean Society of London , later serving on its council (1910 - 1915) and as vice-president during 1912- 1913. [ 5 ]


In 1920 she was the president of the botanical section of the  British Association for the Advancement of Science . She also served as president of the Genetics Society, between 1936 and 1938. [ 6 ]


During  World War II  she served as a volunteer helping the  Allied forces . She died soon after returning to Britain, in 1945, after suffering injuries in a bicycle accident.


Saunders' earlier research focused on genetics. Many of her genetic experiments led to her and  William Bateson  defining important terms like "allelomorphs" (nowadays referred to as  alleles ),  heterozygote  and  homozygote . [ 7 ]  Furthermore, together with Bateson and  Reginald Punnett  she co-discovered  genetic linkage . [ 8 ]


She also did extensive work in plant anatomy, particularly concerning  gynoecia , having published several articles on the subject (noteworthy is her series of articles on "Illustrations of Carpel Polymorphism" published in the journal  New Phytologist  between 1928 and 1931).


Franklin (Frank) William Stahl  (born October 8, 1929) is an American  molecular biologist  and geneticist. With  Matthew Meselson , Stahl conducted the famous  Meselson-Stahl experiment  showing that DNA is replicated by a  semiconservative  mechanism, meaning that each strand of the DNA serves as a template for production of a new strand.


He is Emeritus Professor of Biology [ 1 ]  at the  University of Oregon 's Institute of Molecular Biology in  Eugene, Oregon .


Stahl, like his two older sisters, graduated from the public schools of Needham, a Boston suburb. In 1951, he was awarded an AB degree in biology from  Harvard College , and matriculated in the biology department of the  University of Rochester . His interest in genetics was cemented in 1952 by his introduction to bacterial viruses ( phages ) in a course taught by  A. H. (Gus) Doermann  at the  Cold Spring Harbor Biological Laboratory . In 1956, he received a PhD in biology for his work with Doermann on the genetics of  T4 phage . In 1955, he undertook postdoctoral studies with  Giuseppe Bertani  (in the  Phage group ) at  Caltech  ( Pasadena ) with the aim of learning some  bacterial genetics . He subsequently turned his attentions to collaborations with  Charley Steinberg  and  Matt Meselson . With Steinberg, he undertook mathematical analyses of T4 growth, mutation, and genetic recombination. With Meselson, he studied DNA replication in  Escherichia coli . That study produced strong support for the semiconservative model proposed by  Jim Watson  and  Francis Crick . [ 2 ]


For one year, Stahl served on the zoology faculty at the  University of Missouri  in  Columbia, Missouri  before accepting, in 1959, a position in the new Institute of Molecular Biology at the  University of Oregon  in  Eugene . In the succeeding years, his research involved the phages T4 and  Lambda  and the budding yeast,  Saccharomyces cerevisiae , with his primary focus on genetic recombination. He taught various genetics courses at Oregon and presented phage courses in America, Italy and India. He undertook sabbatical studies in Cambridge, UK, Edinburgh, Jerusalem, and Cambridge, Massachusetts. [ 2 ]


Stahl's research was undertaken in association with numerous colleagues, especially his long-term associates Jean M. Crasemann (1921–1992), Mary M. Stahl (1935–1996), and Henriette (Jette) M. Foss (1937–date). [ 2 ]  Since his retirement in 2001, he lives with Jette and four  llamas  in Eugene, where he continues to submit research papers and participates in University of Oregon governance.


Stahl and his wife Mary (married in 1955) raised two boys and a girl. Surviving are Andy Stahl, a forester and political activist, and Emily Morgan, a hairdresser and shop owner. With his partner, Jette, he shares five children (plus spouses) and eight grandchildren, of whom five are adopted. [ 2 ]


In bacteria:


In phage T4:


In Lambda:


In Yeast:


1997- 			Fellow,  American Academy of Microbiology


1996 			 Thomas Hunt Morgan Medal  (from  Genetics Society of America )


1986- 			Associate Member  EMBO


1985- 			 American Cancer Society  Research Professor


1985-1990		 MacArthur Fellow


1981-	 		Member,  American Academy of Arts and Sciences


1976- 			Member,  National Academy of Sciences


1975-76; 1985-1986	 	 Guggenheim Fellow


1969-70		 NIH  Special Postdoctoral Fellowship


Honorary Doctor of Science:  Oakland University  and  University of Rochester


Joan Elaine Argetsinger Steitz  (born January 26, 1941) is Sterling Professor of Molecular Biophysics and Biochemistry at  Yale University  and Investigator at the  Howard Hughes Medical Institute . She is known for her discoveries involving  RNA , including ground-breaking insights into how  ribosomes  interact with  messenger RNA  by complementary base pairing and that introns are spliced by  small nuclear ribonucleic proteins (snRNPs) ,  which occur in  eukaryotes . [ 4 ] [ 5 ] [ 6 ] [ 7 ] [ 8 ]  In September 2018, Steitz won the  Lasker-Koshland Award for Special Achievement in Medical Science . The Lasker award is often referred to as the 'American Nobel' because 87 of the former recipients have gone on to win Nobel prizes. [ 9 ]


Steitz was born in  Minneapolis ,  Minnesota . [ 10 ]  She grew up in Minnesota in the 1950s and 60s and attended the then all-girls  Northrop Collegiate School  for high school.


In 1963, Steitz received her  Bachelor of Science  degree in  chemistry  from  Antioch College , Ohio, where she first became interested in molecular biology at  Alex Rich 's  Massachusetts Institute of Technology  laboratory as an Antioch "coop" intern.


After completing her undergraduate degree, Steitz applied to medical school rather than graduate school since she knew of women medical doctors but not women scientists. [ 11 ]  She was accepted to Harvard Medical School, but having been excited by a summer working as a bench scientist in the laboratory of  Joseph Gall  at the University of Minnesota, she declined the invitation to Harvard Medical School and instead applied to  Harvard 's new program in  biochemistry  and molecular biology. There, she was the first woman graduate student to join the laboratory of Nobel Laureate  James Watson , with whom she first worked on  bacteriophage   RNA . [ 12 ]


Steitz completed  postdoctoral research  at the  Medical Research Council  (MRC)  Laboratory of Molecular Biology  (LMB) at the  University of Cambridge  (UK), where she collaborated with  Francis Crick ,  Sydney Brenner , and  Mark Bretscher . At the LMB, Steitz focused on the question of how bacteria know where to start the "reading frame" on  mRNA . In the process, Steitz discovered the exact sequences on a mature RNA virus encoding three proteins where the virus mRNA binds bacterial  ribosomes  to produce proteins.  In 1969 she published a seminal paper in  Nature  showing the nucleotide sequence of the binding start points. [ 13 ]


In 1970, Steitz joined the faculty at  Yale . In 1975, she published a research finding for which she is widely known, demonstrating that ribosomes use  complementary base pairing  to identify the start site on mRNA. [ 14 ] [ 15 ]


In 1980, Steitz in collaboration with Michael Lerner published another critical paper, using immunoprecipitation with human antibodies from patients with autoimmunity to isolate and identify  snRNPs  (pronounced "snurps") and detect their role in  splicing . [ 4 ]   A snRNP is a specific short length of RNA, around 150 nucleotides long, associated with protein, that is involved in splicing introns out of newly transcribed RNA (pre-mRNA), a component of the  spliceosomes . Steitz's paper "set the field ahead by light years and heralded the avalanche of small RNAs that have since been discovered to play a role in multiple steps in RNA biosynthesis," noted  Susan Berget . [ 11 ]


Steitz later discovered another kind of snRNP particle, the  snoRNP , involved in an important minority of mRNA splicing reactions.  Via analysis of the genetic locations of the genes for snoRNPs, she demonstrated conclusively that  introns  are not " junk DNA " as they had often been described. Her work helps explain the phenomenon of "alternative RNA splicing." [ 16 ] [ 17 ]   Her discovery of the snRNPs and snoRNPs explains a mysterious finding:  humans have only double the number of genes of a fruit  fly . "The reason we can get away with so few genes is that when you have these bits of nonsense, you can splice them out in different ways," she said. "Sometimes you can get rid of things and add things because of this splicing process so that each gene has slightly different protein products that can do slightly different things. So it multiplies up the information content in each of our genes." [ 18 ]


Steitz's research [ 19 ]  may yield new insights into the diagnosis and treatment of  autoimmune disorders  such as  lupus , which develop when patients make  anti-nuclear antibodies  against their own DNA, snRNPs, or ribosomes. [ 20 ]


Steitz has commented on the sexist treatment of women in science,  and has been a "tireless promoter of women in science," noted Christine Guthrie, who described Steitz as "one of the greatest scientists of our generation." [ 11 ]


Steitz has served in numerous professional capacities, including as scientific director of the  Jane Coffin Childs Memorial Fund for Medical Research  (1991–2002) and as editorial board member of  Genes & Development .


Steitz (born Joan Argetsinger) married  Thomas Steitz , also Sterling Professor of Molecular Biophysics and Biochemistry at Yale and the 2009  Nobel Prize in Chemistry  laureate, in 1966. They have one son, Jon. [ 21 ]


Her nomination for the Royal Society reads:


Joan Steitz is one of the pioneers of the field of RNA biology who is world-renowned for her many seminal contributions. She showed how  ribosomal RNA  is used to initiate translation at the start site of mRNA. She discovered  spliceosomes , the particles that are the sites of splicing of pre-messenger RNA into the final mature mRNA and elucidated many of their roles. She discovered that introns, which were thought to be inert, code for  sno RNAs  that target the modification of other cellular RNAs during their maturation. More recently she has found new roles for  microRNAs  in gene regulation. [ 46 ]


Alexander Rawson Stokes  (27 June 1919 – 6 February 2003) was a British physicist at  Royal Holloway College, London  and later at  King's College London . [ 1 ] [ 2 ]  He was most recognised as a co-author of the second [ 3 ]  of the three papers published sequentially in  Nature  on 25 April 1953 [ 4 ]  describing the correct molecular  structure of DNA . The first was authored by  Francis Crick  and  James Watson , [ 5 ]  and the third by  Rosalind Franklin  and  Raymond Gosling .


In 1993, on the 40th anniversary of the publication of the molecular structure of DNA, a plaque was erected in the Quad (courtyard) of the Strand campus of  King's College London , commemorating the contributions of Franklin, Gosling, Stokes, Wilson, and Wilkins to "DNA X-ray diffraction studies".


Known by the name Alec, [ 6 ] [ 7 ] [ 8 ]  Stokes was born in  Macclesfield , Cheshire. He studied at  Cheadle Hulme School  in Manchester. He received a first-class degree in the natural science tripos in 1940 at  Trinity College, Cambridge  and then researched  X-ray crystallography  of  Imperfect Crystals  for his PhD in 1943 under the supervision of  Lawrence Bragg  at the  Cavendish Laboratory . [ 9 ] [ 10 ]


Stokes lectured in physics at  Royal Holloway College, London  before joining  John Randall 's Biophysics Research Unit at  King's College London  in 1947. He has been credited [ 9 ] [ 11 ]  as being the first person to demonstrate that the DNA molecule was probably helical in shape.  Maurice Wilkins wrote in his autobiography [ 12 ]  that he asked Stokes to predict what a helical structure would look like as an x-ray diffraction photograph, and that he was able to determine this by the next day through mathematical calculations made during a short train journey.  Stokes continued to work on optical diffraction in large biological molecules.  His publications include the books  The Theory of the Optical Properties of Inhomogeneous Materials . London: E. and F.N. Spon Ltd, (1963) and  The Principles of Atomic and Nuclear Physics  C.J. Smith and A.R. Stokes, London, Edward Arnold, (1972)  ISBN   0-7131-2313-3 . [ 1 ]


Stokes retired from  King's College London  as a senior lecturer in 1982. He was a choral singer, played the piano and was an elder in his local  free church , in Welwyn Garden City. [ 13 ]  He died on 5 February 2003, [ 1 ]  survived by his wife, Margaret, two sons, Gordon Stokes and Ian Stokes and a daughter, Jean Stokes. [ 9 ]


Alfred Henry Sturtevant  (November 21, 1891 – April 5, 1970) was an American  geneticist . Sturtevant constructed the first  genetic map  of a  chromosome  in 1911. Throughout his career he worked on the organism  Drosophila melanogaster  with  Thomas Hunt Morgan . [ 2 ]  By watching the development of flies in which the earliest cell division produced two different genomes, he measured the embryonic distance between organs in a unit which is called the  sturt  in his honor. On February 13, 1968, Sturtevant received the 1967  National Medal of Science  from President  Lyndon B. Johnson . [ 1 ] [ 3 ]


Alfred Henry Sturtevant was born in  Jacksonville, Illinois , United States on November 21, 1891, the youngest of Alfred Henry and Harriet Sturtevant's six children.  His grandfather  Julian Monson Sturtevant , a  Yale University  graduate, was a founding professor and second president of  Illinois College , where his father taught mathematics. [ 4 ]


When Sturtevant was seven years old, his father quit his teaching job and moved the family to Alabama to pursue farming.  Sturtevant attended a one-room schoolhouse until entering high school in Mobile. In 1908, he enrolled at  Columbia University .  During this time, he lived with his older brother  Edgar , a linguist, who taught nearby. Edgar taught Alfred about scholarship and research. [ 4 ]


As a child, Sturtevant had created   pedigrees  of his father's horses. While in college, he read about  Mendelism , which piqued Sturtevant's interest because it could explain the traits expressed in the horse pedigrees. He further pursued his interest in genetics under  Thomas Hunt Morgan , who encouraged him to publish a paper of his pedigrees shown through  Mendelian genetics . [ 4 ] [ 5 ]  In 1914, Sturtevant completed his doctoral work under Morgan as well. [ 4 ]


After earning his doctorate, Sturtevant stayed at Columbia as a research investigator for the  Carnegie Institution of Washington . He joined Morgan's research team in the "fly room", in which huge advances were being made in the study of genetics through studies of the fruit fly  Drosophila .  In 1922, he married Phoebe Curtis Reed, and the couple subsequently had three children, [ 4 ]  the eldest of whom was  William C. Sturtevant .


In 1928, Sturtevant moved to Pasadena to work at the  California Institute of Technology , where he became a Professor of Genetics and remained for the rest of his career, except for one year when he was invited to teach in Europe. He taught an undergraduate course in genetics at Caltech and wrote a textbook with  George Beadle . [ 6 ]   He became the leader of a new genetics research group at Caltech, whose members included George W. Beadle,  Theodosius Dobzhansky , Sterling Emerson, and Jack Schultz. He was elected to the United States  National Academy of Sciences  in 1930 and the  American Philosophical Society  in 1936. [ 7 ] [ 8 ]  He was elected a Fellow of the  American Academy of Arts and Sciences  in 1949. [ 9 ]  Sturtevant was awarded the  John J. Carty Award  from the  National Academy of Sciences  in 1965 . [ 10 ]  On February 13, 1968, he received the 1967  National Medal of Science  "For a long and distinguished career in genetics during which he discovered and interpreted a number of important genetic phenomena in Drosophila and other organisms." [ 1 ] [ 3 ]


Sturtevant was interested in  taxonomy  as well as genetics. He loved solving all kinds of puzzles and saw genetics as a puzzle for him to decipher. He was widely read, interested in politics, newspapers, scientific journals across many subjects and crossword puzzles.  He had an impressive memory and composed and edited papers in his head before writing them down from memory.  He enjoyed a long and prosperous career in genetics until his death on April 5, 1970. He died in  Pasadena, California  at the age of 78. [ 3 ] [ 4 ]


Sturtevant accomplished most of his work between 1910 and  World War II . These years saw both  World War I  and the  Great Depression . Prior to World War II, universities and research programs operated under private donations; the federal government was not very involved in the funding of scientific research. Much research prior to World War II concerned the chemical nature of  heredity . World War II changed the course of science. Focus was shifted away from biology and genetics to nuclear chemistry and physics. During and after World War II, the government became the key financial backer of scientific research, in the hopes that funding basic research would lead to technological advances. [ 11 ]  In this same time frame, Sturtevant was an outspoken opponent of  eugenics  and was interested in the effects of the  atomic bomb  on human populations, due to his previous research on lethal genes.  He warned the public of possible harmful genetic effects of nuclear fallout despite supposedly low levels of ionizing radiation.


In 1865,  Gregor Mendel  published a paper entitled “Experiments in Plant Hybridization,” in which he proposed the principles of heredity. This paper introduced the concept of dominant and recessive genes to explain how a characteristic can be repressed in one generation but appear in the next generation. Mendel also assumed that all hereditary factors worked independently of one another, which he explained in his law of independent assortment. Mendel's paper did not achieve much acclaim and was largely forgotten until 1900. [ 12 ]


1865 to 1900 saw a time of theory formulation in the field of heredity/genetics. In 1883,  Wilhelm Roux  argued that the linear structure of  chromosomes  has an impact of making sure daughter cells get equal amounts of chromosomal material. This was the beginning of the chromosome theory; Roux viewed his findings as argument that chromosomes contain units of heredity. [ 13 ]  During this time frame,  Hugo de Vries  put forth a theory that persistent hereditary units are passed through generations and that each “unit” deals with a specific characteristic and the units can combine in different ways in the offspring. [ 12 ]


From 1900 to 1909, anomalous data began to accumulate. Gene linkage was first reported by  Carl Correns  in 1900, contradicting Mendel's law of independent assortment. Thomas Hunt Morgan was the first to provide a working hypothesis for these exceptions. He postulated that genes that remained together while being passed from generation to generation must be located on the same chromosome. [ 12 ]


Sturtevant's most notable discoveries include the principle of  genetic mapping , [ 14 ] [ 15 ]   chromosomal inversion , [ 16 ] [ 17 ]  the first observation of a single gene mutation affecting behavior, [ 18 ]  the first  reparable gene defect, the principle underlying fate mapping, the phenomena of unequal crossing-over, [ 19 ]  and position effect.  His main contributions to science include his analysis of genetic “linkage groups,” which became a classical method of chromosome mapping that we still use today. [ 14 ]   In 1913, he determined that genes were arranged on chromosomes in a linear fashion, like beads on a necklace. [ 2 ] [ 20 ] [ 21 ]  He also showed that the gene for any specific trait was in a fixed location (locus). [ 22 ]


In his work between 1915 and 1928, Sturtevant determined that genes of  Drosophila  are arranged in linear order.  In 1920, he published a set of three papers under the title “Genetic Studies on  Drosophila simulans ,” which “proved that two closely related species had newly recurring mutations that were allelic and thus probably identical”. [ 23 ]   His work also helped to determine the chromosomal basis of  sex determination  and development and described the importance of chromosomal crossing-over or  recombination  in genetic linkage of traits. [ 24 ]


One of Sturtevant's principal contributions was his introduction of the concept that the frequency of  crossing-over  between two genes could help determine their proximity on a linear genetic map.  His experiments determined that the frequency of double crossing over can be used to deduce gene order.  He demonstrated this concept by constructing crosses of three segregating genes, called "three-factor crosses". [ 25 ]   He found that using three genes as opposed to two provided most accurate information about gene order on chromosome.  With this system, Sturtevant discovered that double crossing-over occurs at frequency of equal to or less than the product of two single crossing over frequencies. He also demonstrated the possibility of "unequal crossing-over" and  speculated that it was possibly a main force of evolution. [ 4 ]


Sturtevant's work on the  Drosophila  genome enabled geneticists to further map chromosomes of higher organisms, including human beings. His former Caltech research partner  George Beadle  claimed that modern biochemical genetics stems directly from Sturtevant's work. [ 4 ]


See Scholia for some of his publications.


The  tetranucleotide hypothesis  of  Phoebus Levene [ 1 ]  proposed that  DNA  was composed of repeating sequences of four nucleotides. [ 2 ]  It was very influential for three decades, and was developed by Levene at least into the 1910, and the diagram at the right illustrates the view of Levene and Tipson. [ 3 ]  In 1940, at the time of Levene's death, Bass wrote in his obituary [ 4 ]


As a result of Levene’s work we have an exact concept of the structures of these huge molecules, probably the most complex biological materials whose architectural picture has been reconstructed.


In that form there is an implication that the four bases are present in equal amounts in DNA, and small variations in the experimental values were assumed to be the result of experimental error.


However,  Erwin Chargaff [ 5 ]  showed that the four frequencies were not equal, with variations consistent between different studies. Specifically, according to his  rules  the correct relationship is G = C ≠ A = T. The equalities G = C and A = T suggested that these bases were  paired , this pairing being the basis of the DNA structure that is now known to be correct. Conversely the inequalities G ≠ A etc. meant that DNA could not have a systematic repetition of a fundamental unit, as required by the tetranucleotide hypothesis. Thus there was no reason why the sequence could not store information.


In later years some authorities considered the tetranucleotide hypothesis to have been harmful to the development of molecular biology.  Bentley Glass , for example, called it a "scientific catastrophe". [ 6 ]   More recently, Hargittai [ 7 ]  saw it in a more positive light, and  Frixione and Ruiz-Zamarripa [ 8 ]  wrote as follows:


[Levene's] work was to culminate in Levene and Tipson’s 1935 report showing accurately for the first time the actual molecular structure of DNA, as well as a nearly correct depiction of the RNA structure. This achievement merits the distinction of this paper as a Classic in molecular biology literature.


The  history of genetics  can be represented on a timeline of events from the earliest work in the 1850s, to the  DNA  era starting in the 1940s, and the  genomics  era beginning in the 1970s.


Alexander Robertus Todd, Baron Todd  (2 October 1907 – 10 January 1997) was a British  biochemist  whose research on the structure and  synthesis  of  nucleotides ,  nucleosides , and nucleotide  coenzymes  gained him the  Nobel Prize for Chemistry  in 1957.


Todd was born at  Cathcart  in outer  Glasgow , the elder son of Alexander Todd, JP, [ 1 ]  a clerk with the  Glasgow Subway , and his wife, Jane Lowry. [ 2 ]


He attended  Allan Glen's School  and graduated from the  University of Glasgow  with a bachelor's degree (BSc) in 1928. He received a doctorate (Dr Phil.nat.) from  Goethe University Frankfurt  in 1931 for his thesis on the chemistry of the  bile acids .


Todd was awarded an  1851 Research Fellowship  from the  Royal Commission for the Exhibition of 1851 , [ 3 ]  and, after studying at  Oriel College, Oxford , he received another doctorate (DPhil) in 1933.


Todd held posts with the  Lister Institute , the  University of Edinburgh  (staff, 1934–1936) and the  University of London , where he was appointed  Reader  in biochemistry.


In 1938, Alexander Todd spent six months as a visiting professor at  California Institute of Technology , eventually declining an offer of faculty position. [ 4 ] [ 5 ]  Todd became the  Sir Samuel Hall Chair of Chemistry  and director of the Chemical Laboratories of the  University of Manchester  in 1938, where he began working on nucleosides, compounds that form the structural units of nucleic acids ( DNA  and  RNA ).


In 1944, he was appointed to the  1702 Chair of Chemistry  in the  University of Cambridge , which he held until his retirement in 1971. [ 6 ]  In 1949, he synthesised  adenosine triphosphate  (ATP) and  flavin adenine dinucleotide  (FAD). Todd served as a visiting professor at the  University of Chicago  in Autumn 1948 [ 7 ]  and  University of Sydney  in 1950. [ 4 ] [ 8 ] [ 9 ]


In 1955, he helped elucidate the structure of  vitamin B 12 , although the final formula and definite structure was determined by  Dorothy Hodgkin  and her team, and later worked on the structure and synthesis of  vitamin B 1  and  vitamin E , the  anthocyanins  (the pigments of flowers and fruits) from insects (aphids, beetles) and studied  alkaloids  found in  cannabis . He served as chairman of the  Government of the United Kingdom 's advisory committee on  scientific policy  from 1952 to 1964.


He is credited as the first person to synthesize  H4-CBD  and  H2-CBD  from  Cannabidiol  by  hydrogenation  as early as 1940. [ 10 ]


He received the 1957 Nobel Prize in Chemistry “for his work on nucleotides and nucleotide co-enzymes.”


Elected a  Fellow  of  Christ's College, Cambridge  in 1944, he served as  Master  from 1963 to 1978. Lord Todd became the first  Chancellor  of the new  University of Strathclyde  in 1965, and a visiting professor at  Hatfield Polytechnic  (1978–1986). Among his many honours, including over 40 honorary degrees, he was elected a  Fellow of the Royal Society  in 1942, a member of the United States  National Academy of Sciences  in 1955, [ 11 ]  a member of the  American Academy of Arts and Sciences  in 1957, [ 12 ]  and the  American Philosophical Society  in 1965. [ 13 ]   President of the Royal Society  from 1975 to 1980, The Queen awarded him  the Order of Merit  in 1977. [ 14 ]


In 1981, Todd became a founding member of the  World Cultural Council . [ 15 ]


In 1937, Todd married Alison Sarah Dale (d. 1987), daughter of Nobel Prize winner  Henry Hallett Dale , who like Todd, served as President of the  Royal Society of London .  They had a son and two daughters:


Todd died in Cambridge on 10 January 1997 at the age of 89 following a heart attack. [ citation needed ]


Todd was honoured as a Nieuwland Lecturer at the  University of Notre Dame  in 1948, [ 17 ]  an Arthur D. Little Visiting Professor at  Massachusetts Institute of Technology  in 1954, [ 4 ] [ 18 ]  and a Hitchcock Lecturer at  University of California, Berkeley , in 1957. [ 4 ] [ 19 ]


Knighted  as Sir Alexander Todd in 1954 [ 20 ]  he was elevated as a  Life Peer  on 16 April 1962, being created  Baron Todd  of  Trumpington  in the  County of Cambridge . [ 21 ]


Lord Todd, Master of the  Worshipful Company of Salters  (1961/62) and then  Master of Christ's College  (1963–78), is commemorated by a  blue plaque  erected by the  Royal Society of Chemistry  at the  Department of Chemistry in the University of Cambridge . [ 22 ]