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

Structure of nucleic acids and replication of DNA — practice question

DNA is found in both eukaryotic cells and prokaryotic cells.
(a)[4]

Complete the passage on DNA in eukaryotic cells and prokaryotic cells by inserting the most suitable terms. In eukaryotic cells, the DNA is located mainly in the chromosomes of the nucleus. Chromosomal DNA is associated with proteins called ................................ . Two other eukaryotic cell structures that contain DNA are mitochondria and ................................ . In prokaryotic cells, for example ................................ , the DNA is found in the ................................ and is usually circular.

(b)

Fig. 5.1 illustrates transcription of the first six nucleotides of a gene by the enzyme RNA polymerase. The bases of the first six nucleotides on DNA strand X are shown, but the bases on the template DNA strand are not shown.

(b(i))[1]

State the term used for the non-template DNA strand labelled X in Fig. 5.1.

(b(ii))[1]

Name the RNA strand produced during transcription of a eukaryotic gene.

(b(iii))[1]

Complete Table 5.1 to show the letters of the six bases marked on Fig. 5.1 by numbers 1 to 6.

(c)[3]

RNA polymerase consists of several polypeptides that move together and alter shape as the enzyme carries out its roles. The death cap mushroom, $\textit{Amanita phalloides}$, produces a toxin called alpha-amanitin, which binds to RNA polymerase at a site other than the active site. Alpha-amanitin lowers the activity of RNA polymerase. Use the information provided to suggest how alpha-amanitin lowers the activity of RNA polymerase.

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