what's the relationship between protein structure and cell function?
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Inside our cells -it is a blind, mute and deaf world of roaming/floating molecules! Molecules (including the macromolecules like proteins) wonder almost aimless but can have influence on each other -like, breaking or joining others. But these interactions have to specific. The specific contact and the influence on each other is possible only due to the compatibility in the physico-chemical features on their surfaces, which are directly dependent on the structure.\n\nIt is the proteins that carry out most of the functions in cells. Hence, protein structure is very important for cell function. Because actin is such a basic structural protein and cytochalasin B can interact with it (and affect it), their interactions seem influence activities in different cells and events like fertilization and immune functions. You can look up for literature on this aspect.\n\nI am quoting one abstract from the NCBI's PubMed database (Journal -Biochim Biophys Acta. 1980 Dec 16;626(2):494-500.; PMID: 6894243)of research work by  Maruyama K, Hartwig JH &Stossel TP.:\n\nCytochalasin B and the structure of actin gels. II. Further evidence for the splitting of F-actin by cytochalasin B.\nCytochalasin B decreased the flow birefringence and s20,w and increased the extinction angle of actin filaments in salt solutions favoring polymerization of the protein. These changes occurred without a detectable increase in the equilibrium actin monomer concentration determined by a radioassay. These results complement earlier observations indicating that cytochalasin B shortens actin filaments without net depolymerization. Analyzed in terms of Flory's classical network theory, this shortening accounts for the marked effect of cytochalasin B in dissolving the gel structure of F-actin crosslinked by actin-binding protein concentrations near the critical concentration for incipient gelation. Cytochalasin B decreased the annealing rate of low concentrations of actin filament fragments prepared by sonic disruption. The result is consistent with the idea that cytochalasin B binds to the ends of actin filaments, and may explain how cytochalasin B causes filament shortening.
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The answer is A of course. The other answers doesn't make sense.  They are referring to the ....lysosomes.... ok. Ribosomes synthesize proteins for the cell.
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All the answers are here --> http://en.wikipedia.org/wiki/Cell_%28biology%29\n(and in your book)
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Proteins are macromolecules. They are constructed from one or more unbranched chains of amino acids; that is, they are polymers. A typical protein contains 200–300 amino acids but some are much smaller (the smallest are often called peptides)\n\nWe know Proteins are Broken down from Protease and can be then broken further down into amino acids.\n\nWhy do we need Proteins for?\nWell ahve a look.\n\nMotion and locomotion of cells and organisms depends on contractile proteins. [Examples: Muscles] \nThe catalysis of all biochemical reactions is done by enzymes, which contain protein. \nThe structure of cells, and the extracellular matrix in which they are embedded, is largely made of protein. [Examples: Collagens] (Plants and many microbes depend more on carbohydrates, e.g., cellulose, for support, but these are synthesized by enzymes.) \nThe transport of materials in body fluids depends of proteins. [See Blood] \nThe receptors for hormones and other signaling molecules are proteins. \nProteins are an essential nutrient for heterotrophs. \nThe transcription factors that turn genes on and off to guide the differentiation of the cell and its later responsiveness to signals reaching it are proteins.\n\n4) Strcuture of a Protein\n\nProteins fold into a variety of 3-dimensional shapes. Experiments to unfold and refold proteins have shown that the amino acid sequence itself contains all the instructions needed for proper folding. Scientists have searched for rules governing folding but have found no reliable way to predict a 3-dimensional structure from a simple sequence.\n\nKnowing a protein's sequence does help, however. Having determined \n\n3) Importance of Proteins\nThere are proteins that build muscle, transport protein that carry nutrients, enzymes that 搄ump start?cellular activity, protein hormones involved in regulating metabolism, structural proteins like collagen, and special proteins needed for antibody production. Proteins are thus involved in all body functions, and are nessacary for health.\n\nProteins are large molecules that are made up of smaller chains of peptides. Peptides are chains of amino acids that are biochemically bonded together. There are about 50 amino acids is a single peptide chain. During normal digestion the proteins we take in are broken down into its simplest form (amino acids). These amino acids are then absorbed by the body and made back into proteins that the body needs. As we saw before proteins are crucial to a variety of body functions and structure. This is why everybody need to include protein foods in their diet\n\n\nSort of answer Your Question?
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Too many to list and explain here, without copying and pasting  --and why should I do all your uni work for you? ;-)\n\nI will recommend a couple of good text books through.  Well worth a purchase or just get them on loan from your library...\n\nAlberts et al, Molecular Biology of the Cell\nStryer, Biochemistry\n\nIt's been since I bought mine.  Think I got editions 2 & 7 back in 1996 and I know both have been updated a couple of times since.  These are still a GREAT basic resourse for this sort of question.
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The cell is the structural and functional unit of all living organisms, and is sometimes called the "building block of life." Some organisms, such as bacteria, are unicellular, consisting of a single cell. Other organisms, such as humans, are multicellular, (humans have an estimated 100 trillion or 1014 cells; a typical cell size is 10 µm, a typical cell mass 1 nanogram).\n\nThe cell theory, first developed in 1839 by Schleiden and Schwann, states that all organisms are composed of one or more cells; all cells come from preexisting cells; all vital functions of an organism occur within cells, and cells contain the hereditary information necessary for regulating cell functions and for transmitting information to the next generation of cells.\n\nThe word cell comes from the Latin cella, a small room. The name was chosen by Robert Hooke when he compared the cork cells he saw to the small rooms monks lived in.\n\nAll cells, whether prokaryotic or eukaryotic, have a membrane, which envelopes the cell, separates its interior from its environment, regulates what moves in and out, and maintains the electric potential of the cell. Inside the membrane, a salty cytoplasm takes up most of the cell volume. All cells possess DNA, the hereditary material of genes, and RNA, containing the information necessary to build various proteins such as enzymes, the cell's primary machinery. There are also other kinds of biomolecules in cells.
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Due to differences in chemical structures
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The function of a protein depends on its shape.  If you alter the shape of it, you alter its function.  pH is a factor that can alter the shape, because the pKa values of residues on the protein will dictate which residues are or are not protonated, and that will, in turn, affect the manner in which the various amino acids will form internal ionic bonds.\n\nTemperature is another factor.  the stability of intramolecular bonding is dependent on the level of thermal excitation.  If a protein is at a high temperature, the thermal motion of the atoms might upset their abilities to form bonds.  At really high heat, the result will be total denaturation.  At low temperatures, you might even have the opposite problem, with a protein clinging to things in the wrong ways.\n\nFinally, you might alter it by introducing a chemical that reacts with it.  Some proteins need activator molecules to function, others might be inactivated by an inhibitor.  Enzymatic activity occurs in what is called the "active site" of the protein, which is where the substrates bind to the protein and catalysis occurs.  So the activity of the molecule might be altered by changing the arrangement of the moieties in the acive site relative to one another, of there might be a change which permits/blocks access to the active site by the substrate molecules.
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When looking at DNA  the genetic elements are responsible for regulation of a gene. Evidence for influence of chromatin structures impacts on transient vs stable tranfections and nulcesome core structure domen effects histone folds.\n\nYou question is an excellent question. I have a reference for you that address structure and function \n\nReferences: Chromatin Structure and Fucntion, Wolffem 1998 Academic Press\n\nThe structure is very important to function
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DNA->RNA->Polypeptide->Protein
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Molecular Biology of the Cell
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Proteins are large molecules that are made from amino acids, which are small molecules.
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No. The cell membranes are permeable to almost the same things, but specific carrier protein are needed for different functions, and this protein carriers are specific for some cell types.
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they make proteins. And they aren't a cell, they're just part of a cell. So, for instance, if your body needs some insulin, the nucleus sends the ribosomes the instructions in the form of messenger RNA, and transfer RNA brings the appropriate amino acids to the Ribosomes, where the desired protein (in this case, insulin) is assembled out of amino acids.
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The first and most important thing is for the surface area to volume ratio. The smaller the ratio, the more efficient the cell.\n\nAlso, cells are building blocks of something bigger. If we had huge cells, imagine how big we'd have to be in order to hold trillions of them. ;)\n\nThat's about it in the nutshell.
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here's a basic answer about stuff we were recently talkin' about in class.... there are intrinsic and extrinsic proteins... also called integral and peripheral proteins... the first guys completely span the membrane bilayer and the second guys just touch the surface of the membrane or only partially go into it.  Proteins can diffuse laterally in the membrane.  They also decrease the fluidity of the membrane and increase its rigidity.  I believe it's oligosaccarides or carbohydrates can also bind to the proteins.  Most of the proteins function though as transporters.  There's so many transporters that that's a new questions in itself and i don't feel like the typing! ;)
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study of the substances found in living organisms, and of the chemical reactions underlying life processes. This science is a branch of both chemistry and biology; the prefix bio- comes from bios, the Greek word for “life.” The chief goal of biochemistry is to understand the structure and behavior of biomolecules. These are the carbon-containing compounds that make up the various parts of the living cell and carry out the chemical reactions that enable it to grow, maintain and reproduce itself, and use and store energy.\n\nA vast array of biomolecules is present in the cell. The structure of each biomolecule determines in what chemical reactions it is able to participate, and hence what role it plays in the cell's life processes. Among the most important classes of biomolecules are nucleic acids, proteins, carbohydrates, and lipids.\n\nNucleic acids are responsible for storing and transferring genetic information. They are enormous molecules made up of long strands of subunits, called bases, that are arranged in a precise sequence. These are “read” by other components of the cell and used as a guide in making proteins.\n\nProteins (see Protein) are large molecules built up of small subunits called amino acids. Using only 20 different amino acids, a cell constructs thousands of different proteins, each of which has a highly specialized role in the cell. The proteins of greatest interest to biochemists are the enzymes (see Enzyme), which are the “worker” molecules of the cell. These enzymes serve as promoters, or catalysts, of chemical reactions.\n\nCarbohydrates (see Carbohydrate) are the basic fuel molecules of the cell. They contain carbon, hydrogen, and oxygen in approximately equal amounts. Green plants and some bacteria use a process known as photosynthesis to make simple carbohydrates (sugars) from carbon dioxide, water, and sunlight. Animals, however, obtain their carbohydrates from foods. Once a cell possesses carbohydrates, it may break them down to yield chemical energy or use them as raw material to produce other biomolecules.\n\nLipids are fatty substances that play a variety of roles in the cell. Some are held in storage for use as high-energy fuel; others serve as essential components of the cell membrane.\n\nBiomolecules of many other types are also found in cells. These compounds perform such diverse duties as transporting energy from one location in the cell to another, harnessing the energy of sunlight to drive chemical reactions, and serving as helper molecules (cofactors) for enzyme action. All these biomolecules, and the cell itself, are in a state of constant change. In fact, a cell cannot maintain its health unless it is continually forming and breaking down proteins, carbohydrates, and lipids; repairing damaged nucleic acids; and using and storing energy. These active, energy-linked processes of change are collectively called metabolism. One major aim of biochemistry is to understand metabolism well enough to predict and control changes that occur in cells. Biochemical studies have yielded such benefits as treatments for many metabolic diseases, antibiotics to combat bacteria, and methods to boost industrial and agricultural productivity. These advances have been augmented in recent years by the use of genetic engineering techniques.