Exam Questions

Question 1

Describe how a peptide bond is formed between 2 amino acids to form a dipeptide

Answer 1

• Water is removed through a condensation reaction
• the -OH is taken from the carboxyl group of one amino acid and a -H from the amino group from another
• these join to form a peptide bond

Question 2

The secondary structure of a polypeptide is produced by bonds between amino acids. Describe how.

Answer 2

• The H from the amino group has a +ve charge and is attracted to the -ve O from the carboxyl group
• this causes hydrogen bonds to form which causes it to form either a spiral (a-helix) or a B pleated sheet

Question 3

Two proteins have the same number and type of amino acids but different tertiary structures. Explain why.

Answer 3

Because they have a different sequence of amino acids which creates different disulfide, hydrogen and ionic bonds in different places

Question 4

Explain how the active site of an enzyme causes a high rate of reaction (3)

Answer 4

• lowers the activation energy
• because the induced fit causes the active site of the enzyme to change shape
• causing the bonds to form or break

Question 5

How does the drug prevents bacteria producing folic acid (simplified the question) (3)

Answer 5

• They have similar shapes (inhibitors aren’t the same they are complimentary)
• the drug acts as an inhibitor
• compete for the active site

Question 6

What is the meaning of hydroxylating

Answer 6

Addition of hydroxyl group to the molecule