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.

Verified step by step guidance

1. Identify the key function of enzymes in RNA viruses: Enzymes are crucial for various biological processes, including replication and translation of genetic material.
2. Understand the role of host cell enzymes: Host cells typically do not have enzymes that can replicate the RNA genomes of viruses, as their primary function is to replicate the host's DNA genome.
3. Analyze the options: Option b states that host cells lack enzymes that can replicate the viral genome, which aligns with the unique requirement of RNA viruses for specific enzymes to replicate their RNA.
4. Eliminate other options: Options a, c, and d do not directly address the necessity for RNA viruses to have their own enzymes for genome replication. Option c is incorrect as it confuses the role of enzymes with translating mRNA into proteins, which is not the primary reason RNA viruses need their own enzymes.
5. Conclude with the correct answer: The correct answer is b. RNA viruses require their own supply of certain enzymes because host cells lack enzymes that can replicate the viral genome.

Key Concepts

RNA Virus Replication

RNA viruses replicate their genomes using specific enzymes, as they cannot rely on the host cell's machinery. Unlike DNA viruses, RNA viruses often require RNA-dependent RNA polymerase to synthesize their RNA genomes from an RNA template, which is not present in host cells.

Host Cell Machinery

Host cells possess a variety of enzymes for DNA replication and protein synthesis, but they lack the specific enzymes needed for RNA virus replication. This limitation necessitates that RNA viruses carry their own replication enzymes to successfully reproduce within the host.

Viral Protein Translation

Once inside a host cell, RNA viruses must translate their viral mRNA into proteins to assemble new viral particles. This process requires ribosomes and other cellular components, but the initial step of replicating the viral genome relies on the viral enzymes that the virus brings with it.