Question

RNA viruses require their own supply of certain enzymes because

(A) host cells rapidly destroy the viruses.

(B) host cells lack enzymes that can replicate the viral genome.

(C) these enzymes translate viral mRNA into proteins.

(D) these enzymes penetrate host cell membranes.

Short answer

(A) The statement “host cells rapidly destroy the viruses” is false.

(B) The statement “host cells lack enzymes that can replicate the viral genome” is true.

(C) The statement “these enzymes translate viral mRNA into proteins” is false.

(D)The statement “these enzymes penetrate host cell membranes” is false.

Step-by-step solution

Step 1: RNA Viruses

RNA viruses can have nucleic acid in the form of RNA that can be either single-stranded or double-stranded. Examples of RNA viruses are hepatitis C virus, Ebola virus, and retrovirus. Single-stranded RNA may be a positive-strand (mRNA) or a negative sense strand that can replicate via producing mRNA intermediate.

Explanation of option ‘(A)’

Like other viruses, RNA viruses also replicate by using the cellular machinery of the host. They multiply in the host cell and cause disease. Also, they use some enzymes that are encoded by their genome. RNA viruses do not destroy after infecting a host cell rapidly.

Thus,host cells do not rapidly destroy viruses.

Therefore, the given statement is false.

Explanation of option ‘(B)’

RNA genome in RNA viruses is used as a template for mRNA synthesis that requires RNA-dependent RNA polymerase capable of carrying out this process. These polymerases are not found in the host cells and are encoded by the viral genome.

Thus,host cells lack the enzymes necessary to transcribe the RNA of viruses.

Therefore, the given statement is true.

Explanation of option ‘(C)’

The enzyme is coded by the viral genome required for RNA synthesis by using RNA as a template. This enzyme generally is not found in the host cells because host cells do not use RNA as genetic material. When an RNA virus infects a host, it uses its own RNA-dependent RNA polymerase for replication.

Thus,viral enzymes synthesize RNA using the RNA of the virus during infection of a host cell.

Therefore, the given statement is false.

Explanation of option ‘(D)’

For penetrating the host cell membrane, the viral particle has glycoprotein molecules that interact with receptors present on the host cell membrane.

Thus, viral enzymes do not penetrate the host cell membrane.

Therefore, the given statement is false.