Paper 2 · June 2016 · Genetic Engineering

During the formation of recombinant DNA, an mRNA molecule for the required gene is isolated and an enzyme is used to synthesise a complementary DNA (cDNA) copy of it. Which enzyme carries out this conversion of mRNA into cDNA?

Model answer

reverse transcriptase

Explanation

Reverse transcriptase uses an mRNA strand as a template to synthesise a single strand of complementary DNA (cDNA), which is then made double-stranded. This lets a eukaryotic gene be obtained without its introns, since the mRNA has already been spliced.

Derived from ZIMSEC Biology Paper 2, June 2016, Q3

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