Biol160- Week 2 Notes
Biol160- Week 2 Notes BIOL 160 - 021
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BIOL 160 - 021
Mary Alison Bennett
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This 4 page Class Notes was uploaded by Mary Alison Bennett on Monday September 21, 2015. The Class Notes belongs to BIOL 160 - 021 at University of Tennessee - Knoxville taught by Purnima D Pinnaduwage in Fall 2015. Since its upload, it has received 178 views. For similar materials see Cellular and Molecular Biology in Biology at University of Tennessee - Knoxville.
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Date Created: 09/21/15
Cellular amp Molecular Biology Chapter 3 Week 2 Proteins The Structure of Proteins o A hydrogen atom H 0 An amino functional group NH2 0 A carboxyl functional group COOH o A distinctive Rgroup or side chain Side Chains H H O 0 H H H 0 H3N c c H3N J C J 0 H3N c o H3N Co H3N C quot 0 V H H393CCH 0 CH3 39 quot use Eris tn Glycine G Alanine A Valine V Leucine L lsoleucine I Nonpolar Gly Ala Val Leu lle side chains H o H3N Clt H yo 0 H 0 Hi 0 H3Nic o Hthc c ltCH39 1 o l39 CH2 CH3 Methionine M Phenylalanine F Tryptophan W Proline P Met Phe Trp Pro H H I O H o I o H H H H N C C l H3N C C I O I 0 o 3 I o HgNLC Clt o H3N c c H3N c c H3N C H2 clI 0 H2 2 Polar side CH2 0 CI 0 CH2 0 IC ICH2 chains Ho CH3 5 C OH H2N 0 HZN o Serine S Threonine T Cysteine C Tyrosine Y Asparagine N Glutamine Q Ser Thr Cys Tyr Asn Gln Acidic Basic H H H 0 I o l 0 H3N c c H3N c c o H3N C Clt quot o T o CH2 o i 2 H3N c c Electrically I quot2 l 0 charged H2 Hz CH39 H side chains CH2 l gt N NH CH2 NH2 NH3 NH Aspartate D Glutamate E Lysine K Arginine R Histidine H Asp Glu Lys Arg His Figure 3 5 Biological Science 2e 2005 Pearson Prentice Hall Inc 0 Side chains can be acidic basic polar but uncharged or nonpolar 0 Determining they type of side chain 0 Negatively charged 9 acidic it has donated H ions to its surroundings o Positively charged 9 basic it has picked up surrounding H ions Cellular amp Molecular Biology Chapter 3 Week 2 o Is there an O atom 9 uncharged polar there is a polar covalent bond Side Chains Functional Groups and Reactivity Side chains will contain different functional groups which will affect their reactivity Polar side chains will be hydrophilic polar likes polar Nonpolar side chains will be hydrophobic Different functional groups in side chains will also affect formation of entire proteins Peptide Bonds Proteins form by connecting amino acids with peptide bonds Peptide bonds form through a condensation reaction between two monomers amino acids in this case HO Monomer H L H l 7 l Mgloinler H H 0H Peptide bonds can be broken through hydrolysis putting water in Electron sharing from the N makes the peptide bond very similar to a double bond more stable Important qualities of the Peptide Bond Side chain orientation side chains will interact with each other and with water Directionalify the protein backbone will always have an amino group NH3 on one end and a carboxyl group COO39 on the other 0 The amino end is the Nterminus and the carboxyl end is the Cterminus Flexibility the peptide bond itself cannot rotate but the single bonds on either side of it can meaning that protein structure is flexible What do Proteins Look Like Proteins are incredibly diverse in their structure and function despite there only being 20 different amino acids Cellular amp Molecular Biology Chapter 3 Week 2 0 Due in part to large number of amino acids that make up proteins and the huge number of interactions that can form between so many side chains 0 FUNCTION COMES FROM STRUCTURE Primary Structure 0 The unique sequence of amino acids in proteins 0 Absolutely fundamental to the other structure levels 0 Just one misplaced amino acid can cause a major malfunction sickle cell Secondary Structure 0 Arises from hydrogen bonding between different parts of the amino acids 0 Hbonding can occur between carbonyl and amino groups of two different amino acids 0 Gives rise to either ochelix or Bpleated sheet 0 a helix the backbone of the polypeptide coils o Bpleated sheet parts of the backbone bend to fold into the same plane 0 Depends on the primary structure especially the properties of the amino acids involved Tertiary Structure o Arises form side chain interactions including 0 Hydrogen bonds between polar side chains and opposite partial charges in other side chains or the backbone o Hydrophobic interactions in aqueous solution hydrophilic side chains interact with H20 molecules but hydrophobic side chains form globular masses 0 Van der Waals interactions electrical attractions that occur between all molecules Very weak but helps stabilize hydrophobic side chains that are very close 0 Covalent disulfide bonds strong links that connect different distinct regions of the polypeptide or even two separate polypeptides Cellular amp Molecular Biology Chapter 3 Week 2 o lonic bonds form between groups that have full and opposite charges 0 All of these different types of interactions can occur in one polypeptide leading to very diverse possibilities Quaternary Structure 0 Many proteins have multiple polypeptide subunits interacting to make one structure 0 The exact bonding that occurs is quaternary structure Folding and Function 0 Folding typically happens spontaneously the folded form is usually more stable 0 Proper folding is vital to proper function 0 Unfolded or denatured proteins are pretty much useless 0 Sometimes proteins spontaneously form incorrectly in which case molecular chaperones help them reach the proper formation 0 Folding is often regulated by the chaperones to ensure the best functioning of the organism they re in What do Proteins Do 0 Cafalysis further explained in the next section 0 Defense attack and destroy viruses and diseasecausing bacteria 0 Movement proteins move the cell itself and different cargo inside the cell 0 Signaling send and receive signals cell to cell trigger different enzymes 0 Structure compose fingernails and hair keep blood cells in shape 0 Transport allow certain molecules to enter and exit cells Enzymes and Catalysis o Cafalysis probably the most vital and fundamental function of proteins 0 Enzymes catalytic proteins located in specific sites within the cell 0 Enzymes bind substrates reactant molecules 0 Most enzymes are proteins but some are RNA
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