Reverse transcription
In genetics, reverse transcription is the synthesis of DNA using an RNA template. During this process, the nucleobases of the RNA (A - U - G - C) are transcribed into the nucleobases of the DNA (A - T - G - C). Instead of uracil is thymine and instead of ribose is deoxyribose in DNA before. The reverse transcription is done by the enzyme reverse transcriptase . The reverse case of generating RNA from a DNA template is transcription .
Occurrence
Reverse transcription is mainly used by retroviruses . In retroviruses, the genome consists of RNA, which must first be rewritten into DNA before it can be transcribed and translated . In addition, the RNA is used to smuggle its genetic information into a host cell. There the RNA is transcribed by the reverse transcriptase and then incorporated into the host genome by the integrase . There it is called a provirus .
In eukaryotes, reverse transcription is used to lengthen the telomeres . The reverse transcriptase in this case is called telomerase and uses telomerase RNA as a template.
There are many repetitive sections in the genome , such as transposons . The retrotransposons multiply by first being transcribed, then DNA is recovered via reverse transcription, which can be inserted into the DNA.
The reverse transcription process
With the help of a tRNA primer, the reverse transcriptase first transcribes the single-stranded RNA into a complementary DNA strand (steps 1–4; activity as RNA-dependent DNA polymerase ). The RNA is then broken down down to a fragment that serves as a second primer (step 5; activity as ribonuclease H ). The double-stranded DNA is then produced (steps 6–9; activity as DNA-dependent DNA polymerase ).
Individual evidence
- ↑ retroviruses. Retrieved February 26, 2020 .
- ↑ THE GREAT JUMPING - Wissenschaft.de. Retrieved February 26, 2020 .
- ↑ John M. Coffin, Stephen H. Hughes, Harold E. Varmus: Overview of Reverse Transcription . Cold Spring Harbor Laboratory Press, 1997 ( nih.gov [accessed February 26, 2020]).