BIO 116 Ch. 4
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BIO 116 Ch. 4
parasites that need to enter and take control of a cell to replicate
What do all viruses have as their genetic material?
DNA and RNA
What does the genetic material in a virus contain information for?
how to make viral proteins and the viral protein coat/envelope
What does the protein coat/envelop do for a virus?
it protects the genetic material from the host organism
What do viruses depend on their host cells for?
What are the 4 main places for viruses to enter your body?
respiratory tract (like breathing)
digestive tract (eating)
anal/genital tract (vagina, anus, p-hole)
breaks in skin (like a cut)
an initial infection at the point of entry into your body
new site of infection after the initial infection site
What are the 4 stages of a virus infection cycle?
1) virus is bound to the cell surface
2) virus enters and is uncoated
3) virus is incorporated into the host cell's DNA
4) new virus particles are assembled
protein on the cell surface that binds with the virus protein
kills the host cell after assembling the new virus particles
doesn't kill the host cell after assembling the new virus particles
the virus inserts its genetic material (DNA) into the host cell’s chromosome and remains hidden, not producing new viral particles, until it's reactivated
a virus that was hidden and inactive is reactivated to start making new virus particals
Do antibiotics work on viruses? Why or why not?
NOPE because viruses aren't technically living organisms
How can we typically treat a virus?
just take some medications to ease the symptoms, get plenty of rest, and let the virus run it's course
What is the best defense against a virus?
education and prevention (vaccines)
What do antiviral medications do?
try to exploit weak points in a viruses life cycle and interrupt it
their genetic material is RNA and they must convert their genetic message into DNA instead of DNA -> RNA (the normal way)
proteins that are part of the protein coat, which the immune system cells may be able to mount a response against
responsible for the reverse transcription or copying of the viral RNA into a DNA version
responsible for the maturation of viral proteins once new viruses are made and ready to leave the host cell
help the DNA copy of the virus to integrate or enter and splice into the host cell’s DNA
enzymes that are involved in the copying of genetic material
(envelope proteins) these proteins will become a part of the membrane that surrounds new core virus particles
What are the two important env proteins in HIV?
gp120 and gp41
Where is HIV-2 isolated in?
What's is HIV's host cell receptor called?
Which HIV envelope protein binds to the HIV receptor?
What is the primary target of HIV?
What must there be for HIV to
the cell? What does it bind?
co-receptor; protein called gp-41
When HIV infects a T-helper cell, what are the two things it could do?
spread viral particles and kill the cell
T-helper cell will latently harbor the cell for reactivation
When HIV infects a macrophage, does it kill the macrophage after producing viral particles?
Why can't HIV infect a dendritic cell? What does this cause?
it has a surface receptor that hold HIV on the surface; the dendritic cell brings HIV to the lymph nodes where it infects new T-helper cells
What does the ELISA test for?
How accurate is the ELISA test?
over 99.9% accurate (less that 1/1000 are mistaken for false negative/positive)
If the ELISA test comes back positive, what do they do to double-check?
they use the Western blot test to test for HIV-specific antibodies
How long could it take for someone to make antibodies against HIV?
up to 6 months
What does the PCR test look for?
HIV DNA in infected cells OR HIV RNA in virus particles
What are the three reasons that HIV might evade the immune system?
high mutation rate
a virus is passed directly from cell to cell and spends no time at all outside the cell (where it can be detected)
How does AZT work against HIV?
it's a mutated form of thymidine and takes the place of it so that DNA can't be copied
nucleoside reverse transcriptase inhibitors (NRTI):
drugs that inhibit the reverse transcriptase to copy and spread HIV
What is a bad side effect of AZT?
it gets into the host cell's DNA and kills the host cell
drug that blocks the enzyme called protease and makes HIV inactive
Where did HIV-1 come from?
Where is HIV-2 only found?