Microbiology: Viral Life Cycle

Viruses can not replicate by themselves.

They depend on the host's replication organelles to replicate.The host's ribosomes will make the necessary protein coats and polymerases that replicate the viral genetic material.

Retroviruses contain their own reverse polymerase to convert RNA to DNA before the host's polymerases take over.

The steps involved are: attachment to host, penetration of cell membrane or cell wall, and entry of viral genetic material

Host's ribosomes synthesize the necessary enzymes. Host's ATP provides necessary energy. The host also provides the raw materials such as nucleotides and amino acids.

No. The coat proteins and viral genetic material will assemble into viral particles all by themselves.

During the retrovirus life cycle, integration into host DNA occurs.

The viral reverse is known as transcriptase.

Integrase is a virally encoded enzyme.

• First, retrovirus enters the host.
• Transcriptase then converts the viral RNA genome into double-stranded DNA.
• Integrase adds in the viral DNA into the host's genome at a random place.
• When the host replicates, the viral DNA gets replicated also.

Transduction is the transfer of genetic material by viruses.

1. Virus infects cell: host DNA degraded into fragments, viral DNA takes over control.
2. Host DNA fragment gets packed into virus progeny by accident.
3. Virus progeny infects another cell, injects previous host's DNA fragment.
4. Fragment enters cell, find its homologous counterpart, and crossover.