Tag: molecular biology

Temin and Baltimore discovered reverse transcriptase or RNA dependent DNA polymerase at the same time but independently of each other. For their discovery of the viral enzyme reverse transcriptase, Howard Temin and David Baltimore shared the 1975 Nobel Prize for Physiology or Medicine. Temin discovered reverse transcriptase in Rous sarcoma virus. Baltimore arrived at the same discovery through his studies on replication of RNA containing viruses starting with poliovirus and then moving to vesicular stomatitis virus where he discovered a virion RNA polymerase. 

Complimentary DNA( cDNA) is DNA synthesized from a single-stranded RNA template in a reaction catalyzed by the enzyme reverse transcriptase. RNA of viruses first synthesizes complementary DNA (cDNA) through reverse transcription. DNA then transfers information to RNA which takes part in the translation of coded information to form a polypeptide. 

Unlike other DNA polymerases, reverse transcriptase (RT) is unique in that it is able to make a complimentary DNA strand from an RNA template. Reverse transciptases are usually found in retroviruses, which use RT to make a DNA copy of their own RNA genome, which is then incorporated into the host cell's genome. 

A codon is defined as a sequence of three nucleotides which together form a unit of genetic code in a DNA or RNA molecule. These codon translates to form protein sequences.

Reverse transcription is the process of generating a complementary DNA (cDNA) from an RNA template. The enzyme used is called the reverse transcriptase (RT).

The central dogma of molecular biology says DNA, i.e., deoxyribonucleic acid is replicated first to form a copy of DNA. This process is known as DNA replication and is catalyzed by an enzyme called as DNA polymerase (DNA dependent DNA polymerase). This replicated DNA is then transcribed to form an mRNA (messenger RNA molecule). This process is referred as transcription and this is carried out by an enzyme called as RNA polymerase (DNA dependent RNA polymerase), finally the mRNA is translated into a protein.This process is carried out by ribosomes where amino acids are incorporated. This process is known as translation. Francis Crick proposed this concept of central dogma in molecular biology which states that genetic information flows from DNA->DNA->protein. In some viruses, the flow of information is in reverse direction, i.e., from RNA to DNA. This process is known as reverse central dogma or reverse transcription. It takes place in viruses, acellular organisms where RNA replicates via a DNA intermediate. A complimentary DNA molecule is formed from genomic RNA with the help of an enzyme called reverse transcriptase ( RNA dependent DNA polymerase). Eg : HIV which is a retrovirus.

Teminism is basically a theory. It is also known as reverse transcription. It was discovered by Temin and Baltimore in 1978. In molecular biology, it explains RNA can act as template strand for DNA formation. So, it means that DNA can be synthesized from RNA.

(B) Reverse transcriptase enzyme is responsible for reverse transcription process which cDNA ( complementary DNA) is made from a RNA template.