Viruses Flashcards
define the structure of a virus
genetic material, protein coat, and sometimes an envelope containing lipids
the protein coat is also known as
capsid
explain a benefit of a virus having an envelope
it is easier to kill, since it is sensitive to heat, detergents and desiccation.
why are viruses considered obligate intracellular parasites?
they cannot reproduce independently
why do viruses need a host cell?
to express and replicate genetic information because they lack ribosomes to carry out protein synthesis
a virus replicates and creates:
virions, progeny that are released to infect more cells
bacteriophages target:
bacteria
what is the function of a tail sheath?
inject genetic material into a bacterium
what is the function of tail fibers?
help recognize and connect to the correct host cell
positive sense implies that the genome may be:
a. directly
b. indirectly
translated to functional proteins by the ribosomes of the host cell
a
negative sense implies that the genome requires synthesis of an RNA strand complementary to the negative-sense RNA strand. negative sense RNA viruses must carry a _________ in the virion to ensure that the complementary strand is synthesized
RNA replicase
In retroviruses, how many RNA molecules are found in the virion?
2
Retroviruses carry an enzyme known as ____________ which synthesizes DNA from single stranded RNA. The DNA then integrates into the host cell genome, where it is replicated and transcribed as if it were the cell’s own DNA
reverse transcriptase
true/false: viruses infect cells by attaching to specific receptors, and then either fusing with the plasma membrane, being brought in by endocytosis, or injecting their genome into the cell
true
viral progeny are released through: _____, ______, and ________
cell death, lysis and extrusion
