Question at position 35 The enzyme _____________ is key to the high mutation rate observed in most retroviruses, like HIV. helicasereverse transcriptaseDNA polymeraseInfectaseRNA transcriptaseClear my selection单项选择题
A
helicase
B
reverse transcriptase
C
DNA polymerase
D
Infectase
E
RNA transcriptase

Question

Question at position 35 The enzyme _____________ is key to the high mutation rate observed in most retroviruses, like HIV. helicasereverse transcriptaseDNA polymeraseInfectaseRNA transcriptaseClear my selection单项选择题

A

helicase

B

reverse transcriptase

C

DNA polymerase

D

Infectase

E

RNA transcriptase

BlackTom AI · Accepted Answer

The question asks which enzyme is key to the high mutation rate observed in most retroviruses, such as HIV.
Option 1: helicase. While helicase unwinds DNA or RNA strands during replication, it is not the primary source of the high mutation rate in retroviruses. Helicase’s role is more about strand separation than introducing mutations.
Option 2: reverse transcriptase. This is the correct choice. Retroviruses use reverse transcriptase to convert their RNA genome into DNA. This enzyme lacks robust proofreading activity, leading to a high error rate during cDNA synthesis, which contributes to frequent mutations in the viral genome and rapid evolution.
Option 3: DNA polymerase. In retroviruses, the genome is RNA and is reverse-transcribed into DNA before integration. While DNA polymerases can have proofreading in cellular contexts, the viral enzyme reverse transcriptase is the one lacking proofreading, and DNA polymerase is not the primary enzyme responsible for the high mutation rate in retroviruses.
Option 4: Infectase. This term is not a standard enzyme associated with retroviral replication or mutation processes in biology literature, so it is not a correct descriptor for the mechanism behind the high mutation rate.
Option 5: RNA transcriptase. Although the name sounds plausible, the well-established enzyme in retroviruses that processes the RNA genome into DNA is reverse transcriptase, not a generic RNA transcriptase, and the question targets the known source of elevated mutation rates in retroviruses.
In summary, the elevated mutation rate in retroviruses is mainly attributed to the intrinsic lack of proofreading by reverse transcriptase during reverse transcription, rather than the activities of helicase, DNA polymerase, or nonstandard terms like Infectase or RNA transcriptase.