Biology 9700 · AS & A Level · Structure of nucleic acids and replication of DNA

Structure of nucleic acids and replication of DNA — practice question

Glycogen synthase is one of the enzymes that take part in glycogen synthesis. The monomer unit of the glycogen polymer is $\alpha$-glucose.
(a(i))[2]

Sketch the ring form of $\alpha$-glucose in the space provided.

(a(ii))[1]

Glycogen synthase catalyses bond formation between two $\alpha$-glucose molecules during glycogen synthesis. Name the kind of bond that is formed.

(a(iii))[1]

Another enzyme needed for glycogen synthesis is glycogen branching enzyme. Suggest why glycogen branching enzyme is needed in addition to glycogen synthase.

(b(i))[2]

The gene that codes for glycogen synthase in muscle cells is called $GYS1$. Explain what is meant by a gene.

(b(ii))[3]

There are a number of recognised mutations for $GYS1$. Outline how a mutation in $GYS1$ can lead to the formation of an altered polypeptide where one amino acid is replaced by a different amino acid.

(c)[3]

Table 6.1 gives three functions of cell structures that are involved in the synthesis of glycogen synthase. Complete Table 6.1 by naming the cell structure that performs the function listed.

Worked solution & mark scheme

This 12-mark question has a full step-by-step worked solution and mark scheme. One marking point: accurate ring structure of glucose

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