Lec. 36 - Viruses

Question 1

Describe the components of a virus.

Answer 1

Viruses are made up of genetic material, capsids, viral proteins, matrix proteins, tall fibers or spikes.

Question 2

Compare bacteria and viruses.

Answer 2

Bacteria are prokaryotes, free-living cells that can live inside or outside a body. Viruses can’t reproduce on their own, but they can survive on surfaces for a varying level of time.

Question 3

Explain the viral origins hypotheses.

Answer 3

1. The progressive, or escape, says that viruses arose from genetic elements that gain the ability to move between cells.
2. The regressive, or reduction asserts that viruses are remnants of cellular organisms.
3. The virus-first says that viruses predate or coevolved with their current cellular hosts.

Question 4

Explain process of viral replication.

Answer 4

Attachment, when the virion attaches to the correct host cells. Penetration, when the virus gains entrance into the cell. Synthesis, when the viral proteins and nucleic acid copies are manufactured by the cells’ machinery. Assembly, viruses are produced from the viral components. Release, new formed virions are released from the cell.

Question 5

Compare the lytic vs. the lysogenic pathway in the viral life cycle.

Answer 5

Lytic cycle involves the reproduction of viruses using a host cell to manufacture more viruses; the virus then bursts out of the cell. Lysogenic cycle involves the incorporation of the viral genome into the host cell genome, infecting it from within.

Question 6

Explain how viruses enter a cell and reproduce.

Answer 6

They enter a host cell and use the host’s replication processes to produce progeny virus particles.