Multiple Choice
Which of the following may possess an RNA genome?
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17. Viruses
Viruses
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Why do RNA viruses tend to have unusually high rates of mutation?
A
Because RNA-dependent RNA polymerases lack proofreading ability during genome replication.
B
Because RNA viruses are exposed to higher levels of radiation than DNA viruses.
C
Because RNA viruses incorporate more nucleotides per replication cycle than DNA viruses.
D
Because RNA viruses replicate exclusively in the host cell nucleus, increasing mutation rates.
Verified step by step guidance1
Understand the role of RNA-dependent RNA polymerases in RNA virus replication. These enzymes are responsible for copying the RNA genome of the virus during replication.
Learn about the proofreading ability of polymerases. DNA polymerases typically have proofreading mechanisms that correct errors during replication, reducing mutation rates. RNA-dependent RNA polymerases lack this ability.
Recognize that the absence of proofreading in RNA-dependent RNA polymerases leads to a higher frequency of errors during genome replication, resulting in higher mutation rates in RNA viruses.
Evaluate the incorrect options: RNA viruses are not exposed to higher levels of radiation than DNA viruses, nor do they incorporate more nucleotides per replication cycle. Additionally, RNA viruses do not replicate exclusively in the host cell nucleus; many replicate in the cytoplasm.
Conclude that the correct answer is based on the lack of proofreading ability in RNA-dependent RNA polymerases, which is the primary reason for the high mutation rates in RNA viruses.
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