Proteins
- Created by: Ellie Rivers
- Created on: 01-04-13 13:46
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- Proteins
- Amino Acids
- every amino acid has a central carbon atom
- polypeptides combine to form proteins
- amino group
- are the basic monomers that make polymers
- carboxyl group
- R group
- hydrogen atom
- Secondary structure
- this causes the polypeptide chain to form a 3-D shape
- the two groups form weak bonds called hydrogen bonds
- the -NH group is positive and the -C=O group is negative
- the chain forms an alpha helix
- Polypeptides
- the primary structure determines the ultimate shape of a protein
- this sequence of amino acids form the primary structure of any protein
- a change in a single amino acid can lead to a change in function
- the resulting chain is called a polypeptide
- a change in shape means it will function less well
- many amino acids joining together is called polymerisation
- proteins are commonly made up of a number of polypeptide chains
- Peptide Bonds
- formed from a condensation reaction
- two amino acids are joined by peptide bonds
- combines an -OH from the carboxyl group and a -H from the amino group
- the bond can be broken by hydrolysis
- Tertiary Structure
- the alpha helices can be twisted and folded
- ionic bonds = easily broken
- disulfide bonds = fairly strong
- 3-D shape makes each protein distinct allowing it to function
- hydrogen bonds = easily broken
- Quaternary Structure
- contain a number of individual polypeptide chains
- they may also contain prosthetic groups which are non-protein
- Amino Acids
- Biuret test for proteins, add sodium hydroxide and copper sulfate at room temperature. If the solution turns purple, proteins are present.
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