Year 12 - Proteins and Enzymes

Question 1

Explain how a competitive inhibitor works

Answer 1

• Inhibitor is a similar shape to substrate
• Inhibitor binds to the active site
• fewer enzyme-substrate complexes because less substrate can bind
• so less (named product) produced

Question 2

Explain how a non-competitive inhibitor works

Answer 2

• Inhibitor is not a similar shape to the substrate
• Inhibitor binds at the allosteric site
• Changes the shape of the active site so no longer complementary to substrate
• fewer enzyme substrate complexes as substrate cannot bind.
• so less (named product) forms

Question 3

1. What is the primary structure of a protein?
2. What is the secondary structure of a protein?
3. What is the tertiary structure of a protein?
4. What is the quaternary structure of a protein?
5. What happens if you change the sequence and number of amino acids?

Answer 3

1. Number and sequence of a.a (peptide bonds)
2. Hydrogen bonding between a.a form beta pleated sheets or alpha helix
3. 3D shape determined by placement of ionic, hydrogen and disulphide bonds between R groups of a.a
4. Two or more polypeptide chains joined together
5. Difference sequence of a.a forms different bonds in different places.