BIOL 039 Lecture Notes - Lecture 27: Reverse Transcriptase, Retrotransposon, Moe Williams
Document Summary
Retroviruses and related transposable elements (retro-transposons) utilize the enzyme reverse transcriptase to copy rna into dna. Retroviruses infect eukaryotic cells, and have genomes composed of single-stranded rna. On infection the rna is transcribed into double-stranded dna by reverse transcriptase (an rna-dependent dna polymerase) The dna copies are subsequently inserted at different positions in the host"s genomic dna. The viral genes gag and env are needed to produce new retroviral particles; pol encodes reverse transcriptase. Retrotransposons are related to retroviruses; all carry pol and some contain gag genes. None encode env, thus they can be reverse transcribed and inserted into host dna, but are unable to produce viral particles. Retrotransposons have lost the ability to infect other cells; they are maintained as part of the chromosomes in cells. The gene(s) carried on retro-transposons are flanked by long terminal repeats (ltrs), oriented in the same direction. Examples of retroviruses mmtv, momlv, rsv, hiv, etc.
