Biology 9700 · AS & A Level · Protein synthesis

Protein synthesis — practice question

Collagen is a fibrous protein present in many animal tissues. Fig. 2.1 illustrates the make-up of a collagen fibre.
(a(i))[2]

Describe how the 3 polypeptides are arranged in each collagen molecule.

(a(ii))[3]

Using Fig. 2.1, explain the arrangement of collagen molecules in a collagen fibril and how they are held together.

(b(i))[2]

Suggest two properties of collagen that help cartilage function in the trachea in the gas exchange system of mammals.

(b(ii))[1]

State the role of elastic fibres in the alveoli in the lungs.

(c(i))[1]

Complete Table 2.1 to show the amino acids encoded by the DNA nucleotide sequence in Table 2.1.

(c(ii))[3]

The amino acid sequence you have determined is representative of the entire collagen polypeptide. Explain how this amino acid sequence makes the polypeptide suitable for being part of a collagen molecule.

(c(iii))[2]

Two mutations, P and Q, may affect the primary structure of the polypeptide. Mutation P is a deletion of the first nucleotide pair in the DNA nucleotide sequence shown in Table 2.1. Mutation Q is a substitution of G with T as the first base in the DNA nucleotide sequence shown in Table 2.1. State the effects of mutations P and Q on the primary structure of the polypeptide. mutation P mutation Q

Worked solution & mark scheme

This 14-mark question has a full step-by-step worked solution and mark scheme. One marking point: Each polypeptide has a (left-handed) helix / helical form

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