Scientists are working to find a cure for AIDS. HIV, the virus that causes AIDS, is among the 70 percent of viruses that contain
RNA instead of DNA. The HIV infection mechanism is shown in the diagram. Look at the diagram. Select all the statements that specifically give evidence that HIV is a retrovirus. A. The genetic information is copied from RNA to DNA. B. The genetic information is inserted into the DNA of the host cell, where it may remain inactive for many cell cycles and become activated later. C. The genetic information is transcribed and translated into new viral parts. D. The parts assemble into new viruses and burst from the host cell.
A. The genetic information is copied from RNA to DNA.
B. The genetic information is inserted into the DNA of the host cell, where it may remain inactive for many cell cycles and become activated later.
Explanation:
What characterizes a retrovirus is the presence of the reverse transcriptase enzyme. This enzyme is capable of transforming the single strand of RNA into a double strand of DNA. This is a unique feature of retroviruses, as transformation usually occurs from DNA to RNA (Transcription).
The retroviral DNA produced associates with the host cell chromosomal DNA.
With the formation of DNA, the RNA strand is degraded. However, the DNA produced by reverse transcriptase will also synthesize the new RNA that will constitute the genome of new viruses formed in the infected cell.
Option A, option B. Option A and B are specific to retroviruses, although option c and d are also true, they are not specific only to retroviruses.
Explanation:
Retrovirus is a type of virus that uses RNA as its genetic material. After infecting a cell, a retrovirus uses an enzyme called reverse transcriptase to convert its RNA into DNA. The retrovirus then integrates its viral DNA into the DNA of the host cell, which allows the retrovirus to replicate.
During a solar eclipse, when the Moon's shadow falls on the Earth, we stand in the shadow rather than looking at it. Observers standing in the umbra see a total eclipse of the Sun, while observers under the penumbra see a partial eclipse.
