Protein: Structure

Question 1

Primary Structure

Answer 1

• Sequence of amino acids
• DNA codes for this sequence

Question 2

Secondary Structure

Answer 2

• Hydrogen bonds between amino and carboxyl group
• Can form α-helix and β-pleated sheet
• α-helix - hydrogen bonds every 4th peptide bond
• β-pleated sheet - When 2 parts of the polypeptide chain are parallel to each other

Question 3

Tertiary Structure

Answer 3

• Hydrogen bonding between R groups (broken by temperature and pH changes)
• Disulphide bonds between cysteine amino acids (strongest, broken by oxidation)
• Ionic bonds between charged R groups (stronger than H bonds, broken by pH changes)
• Weak hydrophobic interactions between non-polar R groups

Question 4

Quaternary Structure

Answer 4

• When more than 1 polypeptide chain is involved in the structure
• Each polypeptide chain is a subunit