Biology 9700 · AS & A Level · Protein synthesis

Protein synthesis — practice question

Table 4.1 gives a 12-nucleotide sequence in the template strand of a short DNA segment, together with the matching primary transcript and the four amino acids encoded by the sequence. The table is not complete.
(a(i))[1]

Complete Table 4.1 by showing the nucleotide sequence of the primary transcript produced when this short DNA segment is transcribed.

(a(ii))[1]

Table 4.2 lists every possible template-strand DNA triplet that codes for the amino acids marked aa1, aa2, aa3 and aa4 in Table 4.1. Finish Table 4.3 by naming the four amino acids marked aa1, aa2, aa3 and aa4 in Table 4.1.

(a(iii))[2]

A substitution of a DNA nucleotide is one form of gene mutation. Using the information in Table 4.2, state and explain the effect on the final protein structure of a substitution of the nucleotide at position 3 in Table 4.1.

(a(iv))[3]

A deletion of a DNA nucleotide is another type of gene mutation. Using the information in Table 4.2, state and explain the effect on the final protein structure of a deletion of the nucleotide at position 3 in Table 4.1.

(b)[1]

Nuclear DNA is copied once in each mitotic cell cycle. Six named events linked to the mitotic cell cycle are shown below, though not in sequence. Draw a circle around every event in which nuclear DNA replication occurs: interphase, cytokinesis, $S$ phase, $G_1$ phase, $G_2$ phase, mitosis.

(c)[4]

Describe how DNA is copied inside the nucleus.

(d)[1]

Fig. 4.1 shows the structure of an ATP molecule. State the name of the part of the ATP molecule labelled A in Fig. 4.1.

Worked solution & mark scheme

This 13-mark question has a full step-by-step worked solution and mark scheme. One marking point: Accurate transcription giving complementary RNA sequence with U in place of T

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