Picornaviruses infect a wide variety of eukaryotes, causing a wide variety of di
ID: 177458 • Letter: P
Question
Picornaviruses infect a wide variety of eukaryotes, causing a wide variety of diseases. In humans alone, different picornaviruses cause polio, hepatitis A, and the common cold. They are non-enveloped, meaning the protein capsid is not surrounded by a membrane. Their genome is a single-stranded (+)RNA. The "+" means the genome serves as the mRNA, the (-)RNA strand would be complementary to it, but it is not carried in the virion. There is no DNA intermediate; the new virus RNA is replicated existing RNA by viral proteins. One of the first proteins translated from the (+)RNA is the enzyme responsible for the RNA replication (since eukaryotic cells don't have this enzyme). Propose a basic mechanism for the replication of the single-stranded (+)RNA. Remember, the infected cell will produce hundreds of new viruses; each with its own (+)RNA. Don't worry about the details of how the enzyme does its job, just think about what stages the nucleic acids have to go through, what intermediates might form. This is a hypothesis, so there may be more than one correct answer. Just make sure your answer makes sense in light of the above information and what you know about the normal functioning of DNA and RNA. Use the space under your name on the next page to answer.Explanation / Answer
Viruses when infect they govern the nuclear and cellular mechanisms of a cell. The RNA viruses will make copy of their RNA by following process:
First virus will infect and the RNA (+) will insert into the host cell. The +RNA strand will generate proteins by using the machinery of cell; these proteins will help the viral RNA only. One of those proteins will be reverse transcriptase enzyme which causes the formation of cDNA (complementary) of RNA. That cDNA will turn into double stranded DNA molecule like the host cell has. Now this DNA is able to make hundreds to thousands of copies of viral RNA. And this will be happened by using cellular machinery.