Question

Reverse transcriptases are enzymes that use RNA templates to make DNA.

a. Explain why a reverse transcriptase is commonly found in eukaryotic cells.

b. Why are these reverse transcriptases not found in prokaryotic cells?

Answer 1

a. In Eukaryotes self-replicating stretches of eukaryotic genomes known as retrotransposons utilize reverse transcriptase to move from one position in the genome to another via an RNA intermediate. They are found abundantly in the genomes of plants and animals. Telomerase is another reverse transcriptase found in many eukaryotes, including humans, which carries its own RNA template; this RNA is used as a template for DNA replication.

b. Retrotransposons are found in all eukaryotes but not in prokaryotes. There is a direct correlation between the size of a eukaryotic genome and the abundance but not necessarily the type of retrotransposons as the size of Prokaryotes genome is very small so retrotransposons are not found in prokaryotes. Similarly, Telomeres are present at chromosome terminal or ends and if the chromosomes itself doesn't have any terminal-like circular;ar DNA present in prokaryotes hence it is not needed there.