Question

Complete the following sentences to indicate which gene expression components are found in virus particles. Click on a term and drag into the blank space. A term may be used more than once.

Answer 1

Answer:

1. RNA polymerase is always present in the cell, but sometimes present in viruses.
2. tRNA is always present in the cell but never present in viruses.
3. Ribosomes are always present in a cell but never present in viruses.
4. Genes are always present in the cell, but always present in viruses.

Explanation:

• Viruses are acellular microorganisms that do not have a biochemical or gene expression of their own. They hijack the host's gene expression system.
• RNA polymerase is the enzymes that forms RNA primers during DNA replication and the mRNA transcript of template DNA during transcription. Therefore, RNA polymerase is always required in cells.
• Most viruses lack RNA polymerase except some RNA viruses such as polio viruses that contain an RNA dependent RNA polymerase, an enzyme that synthesizes mRNA from an RNA template.
• Viruses lack tRNA and ribosomes as they are not capable of translation on their own.
• Unlike the gene expression machinery, all organisms including viruses have a genome. Viruses can have both DNA and RNA genomes.