how does genetic mutations occur?
348032
When the proteins that copy your DNA make mistakes.  Hence a mutation
30588
Actually, mutation is normal in every being.\n\nThe genetic code is "divided" (not physically) into TRIPLETS of nitrogened bases. Each triplet codifies for one AMINOACID, which will later form proteins.\n\nNow, the thing is that the same aminoacid can be codified by three or four DIFFERENT triplets. For instance, the aminoacid tryptophan can be codified from the triplets ACU, ACC, ACA and ACG.\n\nAs you may see in that case, the only nitrogen base that changes is the last one (U,C,A,G), but the result of the codification is the same: the aminoacid tryptophan.\n\nSo, in that case, if a mutation occurs in the last nitrogen base, it doesn't really affect anything at all, since tryptophan will still be produced.\n\nThat's what's called a SILENT MUTATION. It has no effect at all in an individual.\n\nThe real problem with mutations start when the first or second nitrogened base of the triplet is mutated. There, the aminoacid that is produced is different that the one is supposed to be produced.\n\nBut even then, if the aminoacid changes the protein (made up from hundreds of aminoacids) might still be the same, without having any effect on the individual.\n\nTo sum up: mutations happen everyday to everyone. The large majority of them has no effect on the general aspect of individuals, and some of them only have minor effects (for example, a mole is the product of a mutation!!!).\n\nWhen they are serious, though, it can lead to any kind of problems, such as cancer and others.\n\nHope it clarified!
900933
There are two aspects of this statement that make it false.  Sorting and recombination of genes occurs during meiosis.  The second false statement concerns the driving of evolution.  The recombination causes variation within a species.  It does not drive evolution.
302707
Genetic mutations are always a risk when manipulating genes.\nGross malformations can occur, thus making it necessary to imprison/destroy the life created.
711783
Evolution doesn't cease to exist simply because there is no need for it.  Genetic variation and mutation are always going to occur.  However, the 'natural selection' aspect of it may not be applicable.
324305
To fix the second response, I must just say that an individual can have any type of mutation; it does not have to be cancer. A carcinogen (cancer-causing substance) is a type of mutagen (a substance that causes mutations in individuals), and there are many chemicals that are not carcinogenic, but are indeed mutagens (exempli gratia, certain base-manipulating mutagens).\n      Now that this is cleared up, I will say that changes in genetic makeup in an individual is a mutation, and in a population, is evolution.\n      In truth, your question is one that can be taught over the period of months. Basically (and I know that my fellow biologists will be mad at me for trying to simplify such a complex subject), over time, the usage and presence of of introns and exons changes. Introns are "intervening" parts of the gene (and are not expressed), and the "exons" are the expressed portions. Introns are the "junk" in an individual's genes, yet over time, a population may realize that this "junk" can actually be useful in adapting to the organism's environment. This results in evolution. I do advise that you read more about the intron-exon system. Evolution is, put simply, changes in an organism's genome, OVER TIME, caused by the reproduction of the fittest of the species.
96132
There have been hundreds of thousands of such experiments done. Moreover you can easily do them yourself using some nutriemt agar and an incubator with a few hundred dollars to pay someone to do the genetic workup.\n\ntalk.origins is your one stop shop for these types of quetsions. The site is highly reputable, well refernces, cites peer reveiewed science journals and most importantly lists literally hundreds of experimenst that show exactly what you describe.\n\nI've attached a couple link to pages that list a dozenor so such mutation studies, but the site has many hundreds of others.
393025
Mutations and birth defects can happen, but this wouldn't be a common event.
897085
Cell regulation or gene regulation?\n\nIf it is cell regulation then mishaps can occur in the signals that trigger responses. Mutation in the receptors or signalling molecules of cells may cause certain pathways to be triggered by accident.\n\nGene regulation mishaps occur when the gene repair mechanism is damaged. Deletions, additions, translocations and inversion can occur in the gene sequence. Housekeeping genes make products that can repair the genes.
425813
Actually the more general answer (evolution) is probably better for this specific question. As I read it, the question is asking: how do alternative versions of genes (changes) appear in a population and then how are they maintained (accumulated)? Not all variation is maintained by natural selection, the other causes of evolution have an effect - drift, migration, nonrandom mating. Mutation is also a cause of evolution although, in the context of this specific question, it's probably better to describe it as the origin/source of the changes.
240849
Cancer is the result of a change in the DNA of a cell that make sthe cell reproduce uncontrollably and to the detriment of other cells. Chnages in DNA are called mutations, and can occur through the influence of chemicals called mutagens.\n\n By lowering the number of mutagens in the environment of an organisms, the chance of any of the cells undergoing a cancerous mutation drops to a lower level. Therefore, finding mutagens is the first step to getting rid of them and thus preventing cancer developing for a longer period of time.
624134
First, I think a lot of people here don't understand what is meant by the genetic code being the same.  It refers to the ribosomal translation table of codon-->amino acid (for example, AUG-->Met).  I think there actually are some variations, but it's the same in most familiar organisms.\n\nAt the molecular level, proteins evolve a few mutations at a time.  If a gene acquired too many mutations at once, the protein product would almost certainly no longer be functional.  What would happen if you were to change the genetic code in an organism?  You would have widespread mutations in almost every single protein in the organism.  What are the odds that the new organism would be capable of surviving?  Very, very low.\n\nThe basic principle is that genes that are absolutely critical for life evolve the slowest.  Thus, the genetic code has not changed as much as other things.
1130993
random mutation, originating from unicelled organisms, which spontaneously formed from organic molecules, which formed naturally due to earths early conditions. this all took really long.
312318
NatBoCheck: Well for starters even creationists believe in microevolution, but then you probably don't know what that is.\n\nGive me a few mins...\n\n"The process of evolution can be summarized in three sentences: Genes mutate. [gene: a hereditary unit] Individuals are selected. Populations evolve."\n\n"The mechanisms of evolution are mutation, natural selection, genetic drift, recombination and gene flow."\n\nMutation\n\nThe cellular machinery that copies DNA sometimes makes mistakes. These mistakes alter the sequence of a gene. This is called a mutation. There are many kinds of mutations. A point mutation is a mutation in which one "letter" of the genetic code is changed to another. Lengths of DNA can also be deleted or inserted in a gene; these are also mutations. Finally, genes or parts of genes can become inverted or duplicated. Typical rates of mutation are between 10-10 and 10-12 mutations per base pair of DNA per generation. \n\nNatural Selection\n\nSome types of organisms within a population leave more offspring than others. Over time, the frequency of the more prolific type will increase. The difference in reproductive capability is called natural selection. Natural selection is the only mechanism of adaptive evolution; it is defined as differential reproductive success of pre- existing classes of genetic variants in the gene pool.\n\nThe most common action of natural selection is to remove unfit variants as they arise via mutation. [natural selection: differential reproductive success of genotypes] In other words, natural selection usually prevents new alleles from increasing in frequency. This led a famous evolutionist, George Williams, to say "Evolution proceeds in spite of natural selection."\n\nNatural selection can maintain or deplete genetic variation depending on how it acts.\n\nGenetic Drift\n\nAllele frequencies can change due to chance alone. This is called genetic drift. Drift is a binomial sampling error of the gene pool. What this means is, the alleles that form the next generation's gene pool are a sample of the alleles from the current generation. When sampled from a population, the frequency of alleles differs slightly due to chance alone.\n\nAlleles can increase or decrease in frequency due to drift. The average expected change in allele frequency is zero, since increasing or decreasing in frequency is equally probable. A small percentage of alleles may continually change frequency in a single direction for several generations just as flipping a fair coin may, on occasion, result in a string of heads or tails. A very few new mutant alleles can drift to fixation in this manner.\n\nRecombination\n\nEach chromosome in our sperm or egg cells is a mixture of genes from our mother and our father. Recombination can be thought of as gene shuffling. Most organisms have linear chromosomes and their genes lie at specific location (loci) along them. Bacteria have circular chromosomes. In most sexually reproducing organisms, there are two of each chromosome type in every cell. For instance in humans, every chromosome is paired, one inherited from the mother, the other inherited from the father. When an organism produces gametes, the gametes end up with only one of each chromosome per cell. Haploid gametes are produced from diploid cells by a process called meiosis.\n\nIn meiosis, homologous chromosomes line up. The DNA of the chromosome is broken on both chromosomes in several places and rejoined with the other strand. Later, the two homologous chromosomes are split into two separate cells that divide and become gametes. But, because of recombination, both of the chromosomes are a mix of alleles from the mother and father.\n\nRecombination creates new combinations of alleles. Alleles that arose at different times and different places can be brought together. Recombination can occur not only between genes, but within genes as well. Recombination within a gene can fo
395275
In nature, living things evolve through changes in their DNA. In an animal like a chicken, DNA from a male sperm cell and a female ovum meet and combine to form a zygote -- the first cell of a new baby chicken. This first cell divides innumerable times to form all of the cells of the complete animal. In any animal, every cell contains exactly the same DNA, and that DNA comes from the zygote.\n\nChickens evolved from non-chickens through small changes caused by the mixing of male and female DNA or by mutations to the DNA that produced the zygote. These changes and mutations only have an effect at the point where a new zygote is created. That is, two non-chickens mated and the DNA in their new zygote contained the mutation(s) that produced the first true chicken. That one zygote cell divided to produce the first true chicken.\n\nPrior to that first true chicken zygote, there were only non-chickens. The zygote cell is the only place where DNA mutations could produce a new animal, and the zygote cell is housed in the chicken's egg. So, the egg must have come first.
417879
This question appears regularly in the question file, so let's take a shot at it. \n\nIn nature, living things evolve through changes in their DNA. In an animal like a chicken, DNA from a male sperm cell and a female ovum meet and combine to form a zygote -- the first cell of a new baby chicken. This first cell divides innumerable times to form all of the cells of the complete animal. In any animal, every cell contains exactly the same DNA, and that DNA comes from the zygote. \n\nChickens evolved from non-chickens through small changes caused by the mixing of male and female DNA or by mutations to the DNA that produced the zygote. These changes and mutations only have an effect at the point where a new zygote is created. That is, two non-chickens mated and the DNA in their new zygote contained the mutation(s) that produced the first true chicken. That one zygote cell divided to produce the first true chicken. \n\nPrior to that first true chicken zygote, there were only non-chickens. The zygote cell is the only place where DNA mutations could produce a new animal, and the zygote cell is housed in the chicken's egg. So, the egg must have come first.
512125
in biology, mutations are changes to the genetic material. mutations can be caused by copying errors in the genetic material during cell division and by exposure to radiation, chemicals, or viruses, or can occur deliberately under cellular control during processes such as meiosis or hypermutation. mutations can be classified based on the effect on the structure of the genetic material:\n\n1. small scale mutations affecting one or a few nucleotides\na. point mutation: exchange of a single nucleotide for another through translations or transversions\na)i. silent mutations: code for the same amino acid\na)ii. missense mutations: code for a different amino acid; i.e. sickle cell anemia\na)iii. nonsense mutations: code for a stop codon, which can truncate the protein\nb. insertions: add one or more extra nucleotides causing a shift in the reading frame (or frameshift)\nc. deletions: remove one or more nucleotides thus altering the reading frame (or frameshift)\n\n2. large scale mutations in chromosomal structure\na. amplifications or gene duplications: leading to multiple copies of chromosomal regions\nb. deletions of chromosomal regions: leads to loss of the genes coded; deletions in chromosome 5p causes cri-du-chat syndrome, deletions in chromosome 15q results in prader-willi syndrome\nc. translocations: interchange of genetic parts from non-homologous chromosomes thus bringing together separate genes to form functionally distinct fusion genes; translocations in chromosome 21 causes down syndrome \nd. inversions: reversing the orientation of a chromosomal segment thus bringing together separate genes to form functionally distinct fusion genes\n\nto detect small scale mutations affecting one or more nucleotides, a variety of tests can be done which in principle will test either the dna composition or the presence/absence of the gene products.\n\nlarge scale mutations in the chromosomal structures can be detected using karyotyping because the chromosomes with mutations would differ in sizes and shapes when compared to the standard. in general the chromosomes with deletions would be relatively smaller and chromosomes with additions would be relatively bigger than their counterparts, while chromosomes with either inversions and translocations would exhibit bridges and/or rings.