Structure of nucleic acids and replication of DNA — Biology 9700 AS & A Level Question & Worked Solution

(a)[4]

Finish Table 5.1 by giving: the name of each base; whether it is a purine or a pyrimidine; and whether it occurs only in an RNA molecule (enter RNA in the table), only in a DNA molecule (enter DNA in the table), or in both RNA and DNA molecules (write both in the table).

(b(i))[1]

Using Fig. 5.1, explain whether carbovir triphosphate will replace a purine nucleotide or a pyrimidine nucleotide in the elongating polynucleotide chain.

(b(ii))[2]

Using Fig. 5.1 and the action of DNA polymerase, suggest why converting abacavir to carbovir triphosphate raises the likelihood that the analogue will be added to the viral polynucleotide chain.

(b(iii))[4]

Suggest and explain how carbovir triphosphate disrupts the action of DNA polymerase and how this may stop the synthesis of viral DNA.

(i)[1]

Using Fig. 5.1, explain whether carbovir triphosphate will replace a purine nucleotide or a pyrimidine nucleotide in the elongating polynucleotide chain.

(ii)[2]

Using Fig. 5.1 and the action of DNA polymerase, suggest why converting abacavir to carbovir triphosphate raises the likelihood that the analogue will be added to the viral polynucleotide chain.

(iii)[4]

Suggest and explain how carbovir triphosphate disrupts the action of DNA polymerase and how this may stop the synthesis of viral DNA.

Structure of nucleic acids and replication of DNA — practice question

Worked solution & mark scheme