GCE A-Level - Higher 2 (H2) · Chemistry (9476)

Proteins: Practice Questions

4 multiple-choice questions marked as you go, and 2 written questions with worked solutions. All on Proteins.

6 questions13 marksFree, no account

Question 1

1 mark

Which reagent and condition can be used to achieve complete hydrolysis of a protein into its individual \(\alpha\)-amino acids?

Question 2

1 mark

A tripeptide is formed from the condensation of three molecules of glycine (\(H_2NCH_2COOH\)). What is the molecular formula of this tripeptide?

Question 3

1 mark

Consider the structure of a protein. Which of the following statements regarding the hydrolysis of peptide bonds is incorrect?

Question 4

1 mark

A polypeptide with the sequence Ala-Gly-Val is completely hydrolysed using concentrated \(HCl(aq)\) and heat. Which of the following species would be present in the reaction mixture at the end of the process?

Question 5

3 marks

Describe the chemical reaction that occurs when a protein is heated under reflux with concentrated aqueous \(HCl\).

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Question 6

6 marks

Proteins are biological macromolecules essential for life.

(a) Describe the formation of a protein from \(\alpha\)-amino acids. In your answer, include the name and structure of the linkage formed between the monomers.

(b) A tripeptide is formed from three units of glycine (aminoethanoic acid, \(H_2NCH_2COOH\)).
(i) Draw the structure of this tripeptide.
(ii) Calculate the relative molecular mass (\(M_r\)) of the tripeptide. (\(A_r: H=1.0, C=12.0, N=14.0, O=16.0\))

(c) Proteins can be hydrolyzed to recover their constituent amino acids. State the reagents and conditions required for the complete hydrolysis of a protein in a laboratory setting.

Write your answer out first, then check it against the worked solution.

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