Biology finals revision

Biology finals revision - UNIT 1 CHAPTER 3: Proteins are...

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UNIT 1 CHAPTER 3: Proteins are composed f building blocks called amino acids . There are around 20 amino acids, all having a common structure. Every amino acid has a carbon atom that makes four bonds: The first bond attached to NH2 (the amino functional group). The second bond links it to COOH (the carboxyl functional group). The third bond links it to a hydrogen atom. The 4 th bond is linked to a side-chain, usually abbreviated as R. Therefore, all C atoms in an amino acid are linked to an amino functional group, a carboxyl functional group, an H atom and an R-group. These R structures are what differentiates the 20 amino acids from each other. They vary from just an H atom to a complex structure containing several C atoms. Amino acids with nonpolar side chains are not capable of forming bonds with hydrogen and therefore do not react with water, and are therefore termed hydrophobic . However amino acids with polar or electrically charged side chains readily interact with water and are therefore termed hydrophilic. Amino acids that have just H and C atoms in their side chains are relatively unreactive, when compared to amino acids that have hydroxyl, amino or carboxyl functional groups in them. Isomers: They are molecules that have different structures but the same molecular formula. There are three types of isomers: 1) Structural isomers have the same atoms but differ in the order in which covalently bonded atoms are attached. 2) Geometric isomers have the same atoms but differ in the arrangement of atoms and groups on either side of a double bond or ring structure. 3)Optical isomers also have the same atoms but differ in the arrangement of atoms or groups around a C atom. How do amino acids link to form proteins: Amino acids link to form proteins by the process of polymerisation. A protein consists of a chain of linked amino acid polymers. Amino acids polymerize when a bond forms between
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This note was uploaded on 04/04/2008 for the course EPP 19-101 taught by Professor Markkieler during the Spring '08 term at Carnegie Mellon.

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Biology finals revision - UNIT 1 CHAPTER 3: Proteins are...

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