Proteins
- Created by: jessicawarren
- Created on: 15-03-16 11:42
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- Proteins
- Structure of amino acids
- Basic monomer units, combine to make polymer
- 20 naturally occur in protiens
- Central carbon atom attached to amino, carboxyl, R group and a hydrogen atom.
- Formation of peptide bond
- Condensation reaction
- Combines OH from carboxyl group of one amino acid with H from amino group of another amino acid
- Two amino acids become linked by peptide bond between C atom and N atom of both amino acids
- Can be hydrolysed to produce two amino acids
- Structure
- Primary: Polypeptide chain of amino acids
- Secondary: Polypeptide coiled into alpha helix
- Tertiary: Helices twisted/folded into 3D shape, maintained by hydrogen, disulfide and ionic bonds.
- Quarternary: Number of polypeptide chains linked in various ways.
- Test for proteins
- Place a sample of solution in test tube and add equal volume of sodium hydroxide solution
- Add a few drops of dilute copper sulfate solution and mix gently
- Purple colouration indicates presence of peptide bonds. If not, solution remains blue.
- Protein bonding
- H bonds form between H atoms with slight + charge and other atoms with slight - charge. In AA, form in hydroxyl, carboxyl and amino groups, provide collective strength
- Ionic bonds form between carboxyl/ amino groups that are part of R groups. + and - groups strongly attracted
- Disulfide links formed between R groups of two cytesines. Strong covalent bnds
- Hydrophobic and hydrophilic interactions cause twisting of amino aid chain which changes shape of protein
- Structure of amino acids
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