Structure of nucleic acids and replication of DNA — practice question

State the name of the mitotic cell-cycle phase in which DNA replication takes place.

In research, scientists may use modified nucleotides to stop elongation of a polynucleotide chain during DNA replication. Fig. 6.1 shows the structure of a DNA nucleotide found in the nucleus of a cell. Fig. 6.2 shows the structure of a modified nucleotide. Suggest how the structure of the modified nucleotide stops DNA polymerase from joining it to another nucleotide.

With reference to Table 6.1, compare how the aptamers affect the affinity of RNA polymerase for its substrate.

With reference to Table 6.1, suggest explanations for the effect of the presence of an aptamer on the rate of transcription catalysed by the RNA polymerase.