biological importance of proteins

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From Wikipedia

Biology

Biology is a natural science concerned with the study of life and living organism s, including their structure, function, growth, origin, evolution, distribution, and taxonomy. Biology is a vast subject containing many subdivisions, topics, and disciplines. Among the most important topics are


From Encyclopedia

protein

protein any of the group of highly complex organic compounds found in all living cells and comprising the most abundant class of all biological molecules. Protein comprises approximately 50% of cellular dry weight. Hundreds of protein molecules have been isolated in pure, homogeneous form; many have been crystallized. All contain carbon, hydrogen, and oxygen, and nearly all contain sulfur as well. Some proteins also incorporate phosphorous, iron, zinc, and copper. Proteins are large molecules with high molecular weights (from about 10,000 for small ones [of 50-100 amino acids] to more than 1,000,000 for certain forms); they are composed of varying amounts of the same 20 amino acids , which in the intact protein are united through covalent chemical linkages called peptide bonds. The amino acids, linked together, form linear unbranched polymeric structures called polypeptide chains; such chains may contain hundreds of amino-acid residues; these are arranged in specific order for a given species of protein. Types of Proteins A protein molecule that consists of but a single polypeptide chain is said to be monomeric; proteins made up of more than one polypeptide chain, as many of the large ones are, are called oligomeric. Based upon chemical composition, proteins are divided into two major classes: simple proteins, which are composed of only amino acids, and conjugated proteins, which are composed of amino acids and additional organic and inorganic groupings, certain of which are called prosthetic groups . Conjugated proteins include glycoproteins , which contain carbohydrates; lipoproteins , which contain lipids; and nucleoproteins, which contain nucleic acids . Classified by biological function, proteins include the enzymes , which are responsible for catalyzing the thousands of chemical reactions of the living cell; keratin , elastin, and collagen , which are important types of structural, or support, proteins; hemoglobin and other gas transport proteins; ovalbumin, casein , and other nutrient molecules; antibodies , which are molecules of the immune system (see immunity ); protein hormones , which regulate metabolism ; and proteins that perform mechanical work, such as actin and myosin , the contractile muscle proteins. Protein Structure Every protein molecule has a characteristic three-dimensional shape, or conformation. Fibrous proteins, such as collagen and keratin, consist of polypeptide chains arranged in roughly parallel fashion along a single linear axis, thus forming tough, usually water-insoluble, fibers or sheets. Globular proteins, e.g., many of the known enzymes, show a tightly folded structural geometry approximating the shape of an ellipsoid or sphere. Because the physiological activity of most proteins is closely linked to their three-dimensional architecture, specific terms are used to refer to different aspects of protein structure. The term primary structure denotes the precise linear sequence of amino acids that constitutes the polypeptide chain of the protein molecule. Automated techniques for amino-acid sequencing have made possible the determination of the primary structure of hundreds of proteins. The physical interaction of sequential amino-acid subunits results in a so-called secondary structure, which often can either be a twisting of the polypeptide chain approximating a linear helix (α-configuration), or a zigzag pattern (β-configuration). Most globular proteins also undergo extensive folding of the chain into a complex three-dimensional geometry designated as tertiary structure. Many globular protein molecules are easily crystallized and have been examined by X-ray diffraction, a technique that allows the visualization of the precise three-dimensional positioning of atoms in relation to each other in a crystal. The tertiary structure of several protein molecules has been determined from X-ray diffraction analysis. Two or more polypeptide chains that behave in many ways as a single structural and functional entity are said to exhibit quaternary structure. The separate chains are not linked through covalent chemical bonds but by weak forces of association. The precise three-dimensional structure of a protein molecule is referred to as its native state and appears, in almost all cases, to be required for proper biological function (especially for the enzymes). If the tertiary or quaternary structure of a protein is altered, e.g., by such physical factors as extremes of temperature, changes in p H, or variations in salt concentration, the protein is said to be denatured; it usually exhibits reduction or loss of biological activity. Protein Synthesis The cell's ability to synthesize protein is, in essence, the expression of its genetic makeup. Protein synthesis is a sequence of chemical reactions that occur in four distinct stages, i.e., activation of the amino acids that ultimately will be joined together by peptide bonds; initiation of the polypeptide chain at a cell organelle known as the ribosome; elongation of the polypeptide by stepwise addition of single amino acids to the chain; and termination of amino-acid additions and release of the completed protein from the ribosome. The information for the synthesis of specific amino-acid sequences is carried by a nucleic acid molecule called messenger RNA (see nucleic acid ). Proteins are needed in the diet mainly for their amino acids, which the body uses to build new proteins (see nutrition ). The mechanism of action of many widely used antibiotics, such as streptomycin , chloramphenicol , and tetracycline , can be understood in terms of their ability to interfere with some stage of protein synthesis in bacteria.


From Yahoo Answers

Question:A. Their 20 monomers are connected in long, complex strings. B. Specific protein shapes enables proteins to have specific functions C. The shape of each protein is determined by genes. D. Genetic mutation produces the small changes in protein function over time that is the basis of evolution E. All are true. First correct answer gets 10 points! Please give a one sentence explanation to WHY it is the right answer!

Answers:E. All are true. As to why, well...they are all true :)

Question:i'm having a test in biology tomorrow and i need to know the 6 types of proteins, and an example of each. so far i have 1. catalytic proteins, ex: RNA polymerase 2. carrier proteins, ex: hemoglobin 3. structural proteins, ex: cytoskeleton 4. contractile proteins, ex: muscle i need an example of a regulatory protein and an immunological protein, if anyone can help me. also, are the examples of the proteins i already posted correct? thanks :D

Answers:Immunological proteins are antibodies Many enzymes are 'regulatory' but if you want a specific example how about fructose 2,6-bisphosphatase, that one plays role in regulating glycolysis

Question:1. Chemical composition of proteins? 2. Chemical reactions involved in protein synthesis? 3. Structure of proteins? 4. Functions of proteins in relation to environmental factors? 5. Role of proteins in intracellular and extracellular exchange of information?

Answers:1. The composition of the proteins come from building blocks called amino acids. There is also DNA, RNA and Enzymes which are also proteins as well. 2. http://www.accessexcellence.org/RC/VL/GG/protein_synthesis.php 3. http://en.wikipedia.org/wiki/Protein_structure 4. This question refers to the denaturing if the protein gets too hot. 5. http://www.britannica.com/EBchecked/topic/479680/protein#tab=active~checked%2Citems~checked&title=protein%20--%20Britannica%20Online%20Encyclopedia

Question:1. What is needed in photosynthesis to convert carbon dioxide into organic molecules? 2. How is the proton gradient generated in chloroplasts during photosynthesis? 3. Why is the action spectrum for photosynthesis similar to the absorption spectra of photosynthetic pigments? 4. What (specifically) produces ATP in mitochondria? 5. To which parts of the deoxyribose molecule do phosphates bind in DNA?

Answers:1. sunlight (energy), chlorophyll (to absorb the light), and a lot of enzymes found inside the chloroplasts of plants. http://en.wikipedia.org/wiki/Photosynthesis 2. By the cytochrome bf complex in the thylakoid membrane of the chloroplast http://en.wikipedia.org/wiki/Chemiosmosis#In_plants 3. Because the phytosynthetic pigments carry out the photosynthesis (sounds like a trick question). 4. The enzyme ATP synthase http://en.wikipedia.org/wiki/ATP_synthase 5. The phosphate groups are bound to the 2-deoxyribose (sugar), on the 3rd and the 5th carbon atoms. The backbone is sugar-phosphate-sugar-phospate-sugar, etc. http://en.wikipedia.org/wiki/Dna I hope that was helpful! Next time, it might be better to split up the question into 5 questions. That way more people will be motivated to answer (and earn 5 times the points).

From Youtube

Biology: Protein Synthesis: An Overview :www.mindbites.com Professor Wolfe provides an overview of the process of protein synthesis. Protein synthesis occurs when a ribosome bonds to mRNA in the cytosol of the cell and has four steps, initiation, elongation, termination and translation. Initiation begins when the start codon binds with the initiator tRNA at the P site. Elongation begins once the second tRNA anticodon binds with the appropriate mRNA codon at the A site. GTP provides the energy that is needed to form the peptide bonds that hold the polypeptide chain together. Termination occurs when the mRNA stop codon binds with a release factor. Translation results in the release of the new polypeptide chain. This lesson is perfect for review for a CLEP test, mid-term, final, summer school, or personal growth! Taught by Professor George Wolfe, this lesson was selected from a broader, comprehensive course, Biology. This course and others are available from Thinkwell, Inc. The full course can be found at www.thinkwell.com The full course covers evolution, ecology, inorganic and organic chemistry, cell biology, respiration, molecular genetics, photosynthesis, biotechnology, cell reproduction, Mendelian genetics and mutation, population genetics and mutation, animal systems and homeostasis, evolution of life on earth, and plant systems and homeostasis. George Wolfe brings 30+ years of teaching and curriculum writing experience to Thinkwell Biology. His teaching career started in Zaire, Africa where he taught Biology ...

Biology: Proteins: Amino Acids :www.mindbites.com Taught by Professor George Wolfe, this lesson was selected from a broader, comprehensive course, Biology. This course and others are available from Thinkwell, Inc. The full course can be found at www.thinkwell.com The full course covers evolution, ecology, inorganic and organic chemistry, cell biology, respiration, molecular genetics, photosynthesis, biotechnology, cell reproduction, Mendelian genetics and mutation, population genetics and mutation, animal systems and homeostasis, evolution of life on earth, and plant systems and homeostasis. George Wolfe brings 30+ years of teaching and curriculum writing experience to Thinkwell Biology. His teaching career started in Zaire, Africa where he taught Biology, Chemistry, Political Economics, and Physical Education in the Peace Corps. Since then, he's taught in the Western NY region, spending the last 20 years in the Rochester City School District where he is the Director of the Loudoun Academy of Science. Besides his teaching career, Mr. Wolfe has also been an Emmy-winning television host, fielding live questions for the PBS/WXXI production of Homework Hotline as well as writing and performing in "Football Physics" segments for the Buffalo Bills and the Discover Channel. His contributions to education have been extensive, serving on multiple advisory boards including the Cornell Institute of Physics Teachers, the Cornell Institute of Biology Teachers and the Harvard-Smithsonian Center for Astrophysics ...