Protiens

• What is the general structure of an amino acid?

  -COOH carboxyl group

  -R group

  -NH2 amino group

  
• Describe how to test for proteins in a sample

  Biuret test confirms the presence of peptide bonds

  1. Add equal volume of sodium hydroxide to sample at room temperature.
  2. Add drops of dilute copper II sulphate solution. Swirl to mix
  3. Positive= colour changes from blue to purple
  4. Negative = solution remains blue.
• How many amino acids are there and how do they differ from each other?

  20

  They differ by R group only.
• How do dipeptides and polypeptides form?

  • Condensation reaction forms peptide bond and eliminates a water
  • Dipeptide: 2 amino acids
  • Polypeptide: 3 or more amino acids.
• How many levels of protein structure are there?

  4
• Define a primary structure of a protein

  • Sequence, number and type of amino acids in the polypeptide
  • Determined by sequence of codons of mRNA
  • One straight line.
• Define secondary structure of a protein

  Hydrogen binds form between O- attached to -C= and H+ attached to -NH.
• Define tertiary structure of a protein

  3D structure formed by the further folding of polypeptide
• Describe the structure and function of globular proteins

  • Spherical and compact
  • Hydrophilic R groups face out and hydrophobic R corpus face in.
  • Involed in metabolic processes