Viruses Dead or alive?. Viral structure Viruses are not cells. Basic structure: –Protein coat...
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Transcript of Viruses Dead or alive?. Viral structure Viruses are not cells. Basic structure: –Protein coat...
Viruses
Dead or alive?
Viral structure
Viruses are not cells.
Basic structure:– Protein coat– Nucleic acid core
(RNA or DNA)-controls production of new viruses
Virus Categories
DNA viruses – stable, do not mutate rapidly– Single-stranded or double-stranded– Smallpox, Hepatitis B
RNA viruses – mutate rapidly, unstable– Single-stranded or double-stranded– HIV, Rhinovirus
Are viruses alive?
Only 1 characteristic of life: reproduction Can only reproduce inside another living
cell= host cell Host Cell: provides a home and or food
for a virus…..host harmed by virus Process or reproduction = lytic cycle
Lytic Cycle
Virus attaches to host cell’s membrane and injects its nucleic acid into the host cell.
The viral nucleic acid takes over protein synthesis, creating new viruses.
The host cell bursts, lyses, releasing the newly formed viruses.
Release
Before attachment
Attachment
Penetration and uncoating
ReplicationAssembly
VIRUS AND HUMANS
Cause a large number of human diseases– Ex. Colds, warts, AIDS, measles, flu, small
pox, mumps, hepatitis
VIRUS AND HUMANS
Can be helpful to humans– Vaccines– Germ Warfare– Change genetic material
VIRUS AND HUMANS
Vaccines: weakened virus that doctors inject into us so our body makes antibodies (fight disease)– Ex. Flu shot
After a person has a virus, they produce antibodies to fight the disease, so they will never get disease again– Ex. Chicken pox
VIRUS AND HUMANS
Germ warfare: use viruses to control pests. – Ex. Rabbits in Australia
Change genetic material– Scientist have learned to put genetic
material into viruses– Hopefully, they’ll be able to use viruses to
replace disease causing DNA in humans