carbon: proteins
Cards (7)
- function:
- speed up chemical rxns (enzymes)
- defense
- storage
- transportation
- cell communication
- structural support
- constructed by the same set of 20 amino acids linked in unbranched polymers
- polypeptide: polymer of amino acid monomers joined via peptide bond
- amino acid (monomers):
- alpha carbon + Hydrogen + amino group + carboxyl group (main body) + r group (side chain)
- r group determines characteristic of amino acid
- categorization of amino acid: nonpolar, polar, acidic, basic
- polypeptides:
- 2 amino acids (carboxyl of 1 + amino group of 1) joined via dehydration rxn to form peptide bond (covalent)
- polypeptide backbone: main chain of bonded amino acids
- chemical nature determined by type and sequence of side chains (determines fold, final shape, + chemical traits)
- structure + function:
- function of a protein depends on ability to recognize + bind to other molecules
- primary structure: linear chain of amino acids bonded via peptide bonds (amino end --> carboxyl end)
- secondary: alpha helix (Hbonds between twisted singular polypeptide backbone) + beta pleated sheets (1 backbone parallel bonded via Hbonds)
- tertiary: 3D shape stabilized by R group interaction (alpha + beta shapes interact via VDW + hydrophobic if NP/Hbond if polar/ionic if charged)
- quaternary: 2+ polypeptides associating via R groups (monomer + monomer = dimer polypeptide)
- sickle cell disease:
- caused by substituting 1 amino acid (valine) for normal amino (glutamic acid) at designated position (6th amino acid) of hemoglobin
- primary level changed - changed shape of blood cell - clogs smaller blood vessels
- determining protein structure:
- folding occurs during protein synthesis inside cell
- depends on physical + chemical conditions of environment
- amino acid sequence, pH, salt concentration, temp, aqueous to nonpolar environment, disruption of Hbonds, ionic bonds, disulfide bonds that maintain shape
- not perfect conditions = denaturation