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Viruses are not __. They are __. They are very small __ (__) particles.
They are __, meaning they ust do what in order to reproduce.
- cells; acellular
- infectious (replicating)
- obligate, intracellular parasites
- infect a host cell and take over that cell's metabolism
What is the capsid?
the protein coat around nucleic acid
Viral envelopes are derived from __.
host cell's membrane
Polio virus only infects __.
Variola (smallpox) virus only infects __.
Plant viruses only infect __.
What are the three steps in virus replication.
- penetration (entry)
Virus attachment is dependent on what?
specific receptors on the surface of the host cell
What viruses use the lytic/ lysogenic cycle?
What are the steps of lytic reproduction?
- entry of phage DNA (penetration) and degradation of host DNA
- Synthesis of viral genomes and proteins
- Release (lysis)
What is different about phages that animal viruses do not do?
Unlike animal viruses that attach, penetrate, and then uncoat, phages' penetration IS their uncoating. They attach and uncoat as they penetrate. Their nucleic acid penetrates into the cytoplasm, but their capsid does not.
provirus= viral DNA incorporated into cellular DNA
What are the steps to the lysogenic cycle?
- Penetration (uncoating)
True or False:
In the lysogenic cycle, the host bacterium becomes unhealthy and dies.
- In the lysogenic cycle, the host bacterium remains healthy and reproduces.
What causes a switch from the lysogenic to the lytic cycle?
Phages that use both the lytic and lysogenic cycle are called __.
Viroids infect what?
Prions infect what?
- no protein
- just nucleic acid
- affect plant growth
- reproduce, multiply, and infect other organisms
- cause brain diseases in mammals
the viral envelope has __
What gives a virus its shape?
What changes shape to fit the other, the virus or the receptor?