Context: Bacteria called Klebsiella pneumoniae can use an enzyme called reverse transcriptase to create new genes when infected with bacteriophages (viruses that attack bacteria).
- This newly created gene produces a protein named Neo, which puts the bacteria in a dormant state, stalling the virus's replication and protecting the bacteria.
Central dogma of molecular biology:
- Central dogma of molecular biology explains how genetic information flows from DNA to RNA to proteins.
- Gene expression is the process our cells use to convert instructions in DNA into proteins. This happens in two-stages called transcription (occurs in the nucleus, in eukaryotic organisms) and translation (occurs in cytoplasm).
- Transcription: mRNA copies the sequence of a gene from DNA, and then leaves the nucleus and travels to cytoplasm.
- Translation: Using the template encoded by mRNA, translation is carried out by ribosomes, i.e., the information in the mRNA is used to synthesise proteins (building blocks of life).
- In prokaryotic cells (such as bacteria), which lack a nucleus, transcription and translation occur in the same cellular compartment, the cytoplasm.
- In eukaryotic organisms, transcription occurs in the nucleus, while translation occurs in the cytoplasm.
Transcription and Translation:
- Transcription is the process of copying DNA into RNA. It is the first step in gene expression, which is the process by which genes are used to make proteins. Transcription occurs in the nucleus of eukaryotic cells. During transcription, the DNA is copied into a complementary RNA molecule. This RNA molecule, called messenger RNA (mRNA), then leaves the nucleus and travels to the cytoplasm, where it is used to synthesise proteins by translation.
- Translation is the process of using mRNA to make a protein. It is the second step in gene expression. Translation occurs in the cytoplasm of eukaryotic cells. Translation is carried out by ribosomes, which use the information in the mRNA to synthesise a chain of amino acids. The chain of amino acids is then folded into a protein.
Reverse transcription:
- Reverse transcription is a process in which RNA is used as a template to synthesise a complementary DNA (cDNA) molecule. This process is carried out by an enzyme called reverse transcriptase. The name "reverse transcription" reflects the fact that it is the reverse of the usual flow of genetic information, which is from DNA to RNA (transcription).
- Transcription occurs in the nucleus of the cell, while reverse transcription can occur in the cytoplasm of the cell.