19.2-4CC - Campbell Biology

Question

Why is HIV called retrovirus?

Step-by-Step Solution

Answer

HIV (human immunodeficiency virus) is called retrovirus because it uses its genetic material, RNA (ribonucleic acid), as a template to synthesize DNA (deoxyribonucleic acid) to infect a host cell. 

Step 1: HIV (human immunodeficiency virus)

Viruses either contain DNA or RNA as the genetic material. HIV is a group of viruses that has RNA as the genetic material. HIV is spherical and is surrounded by an outer shell called an envelope. The capsid is present at the center of the virus.

 

The capsid contains two strands of an RNA molecule. It also contains two enzymes called reverse transcriptase and integrase.

Step 2: Retrovirus

A specific group of viruses contains RNA as the genetic material. These viruses also contain reverse transcriptase enzymes that synthesize DNA using RNA as a template. The DNA copy of their genome is used to infect the host cell. 

 

This group of RNA viruses that uses RNA as a template to synthesize DNA is called a retrovirus. The viruses are so-called because the flow of genetic information from RNA to DNA is the reverse of the central dogma. 

 

Central dogma says genetic information flows from DNA to RNA and then to proteins.

Step 3: HIV is a retrovirus

HIV uses its reverse transcriptase enzyme to synthesize DNA from RNA to enter the human cell and replicate. Like retrovirus, the flow of information in HIV is reversed to that of the central dogma, which means RNA to DNA.

 

As a result, HIV is called a retrovirus.