Q.Retroviruses do not follow central Dogma. Comment.

The Central Dogma of molecular biology describes the unidirectional flow of genetic information from DNA to RNA, and then from RNA to protein.

Retroviruses, such as HIV, possess an RNA genome. They do not follow the typical flow because they first synthesize DNA from their RNA template. This process is catalyzed by the enzyme reverse transcriptase. The newly formed viral DNA then integrates into the host cell's genome, from which it is transcribed into messenger RNA and subsequently translated into viral proteins. This reverse flow of genetic information, from RNA to …

The Central Dogma of molecular biology, as proposed by Francis Crick, describes the fundamental flow of genetic information within a biological system. It states that genetic information flows from DNA to RNA, and then from RNA to protein. This unidirectional flow is typically represented as:

DNA $\rightarrow$ RNA $\rightarrow$ Protein

This means that DNA serves as a template for its own replication, and also for the synthesis of messenger RNA (mRNA) through a process called transcription. The mRNA then carries the genetic code to the ribosomes, where it is translated into proteins. The Central Dogma essentially outlines the standard pathway for gene expression in most organisms.

However, retroviruses present a fascinating exception to this established rule. Retroviruses are a class of viruses that have RNA as their genetic material, rather than DNA. When a retrovirus infects a host cell, it does not immediately proceed to synthesize proteins from its RNA genome. Instead, it employs a unique enzyme called reverse transcriptase.

Here's how retroviruses deviate from the Central Dogma:

• RNA Genome: Unlike most organisms, retroviruses carry their genetic information in the form of RNA.
• Reverse Transcription: Upon entering a host cell, the viral RNA genome is used as a template to synthesize a complementary DNA (cDNA) strand. This process, catalyzed by reverse transcriptase, is known as reverse transcription. It is a reversal of the transcription step in the Central Dogma (RNA $\leftarrow$ DNA, instead of DNA $\rightarrow$ RNA).
• Integration into Host Genome: The newly synthesized viral DNA then integrates into the host cell's chromosomal DNA. At this stage, the viral genetic material becomes a part of the host's own genome. …

Instead of describing reverse transcriptase's action directly, ask what the Central Dogma predicts should NOT be possible: DNA -> RNA -> protein forbids RNA from ever being copied back into DNA. A retrovirus's reverse transcriptase does exactly th …