Cycle 1 Flashcards
T/F HIV is not severe
False: more deaths then malaria, influenza, Ebola and covid-19
T/F HIV is still happening
T
T/F HIV is distributed evenly in the world
F
T/F HIV vaccines don’t exist
T
HIV is more prevalent in Africa because?
Historically, it spread there first so it is like “ground zero”, chimpanzee range overlaps
_____ diseases spread (spill over) to humans from nonhuman animals
zoonotic
Zoonotic diseases are more likely between ______
closely related species
Zoonotic diseases are often not very harmful in the original host but _____
much more harmful in new host
____ has a long history of infecting nonhuman primates
SIV (simian immunodeficiency virus)
Where do viruses fit in the tree of life?
They cant because they are not considered living, they do have a evolutionary history
Viruses do NOT have
Lipid membranes surrounding cytoplasm
Viruses have ____ shell with _____ genome inside
protein, nucleic acid
The nucleic acid can be ___ or ____
DNA or RNA, single or double stranded
What drugs are harder to design and usually have more serious side effects?
Antiviral drugs
Retroviruses, including HIV,
have an ____ genome
RNA
Usually process is DNA, RNA, Protein, but _______ disobey central dogma
Retroviruses
Reverse transcriptase is very fast at what it does but makes a lot of mistakes expressed as _____
mutations
HIV has its genome in the form of RNA but it then converts to ____
DNA
HIV has a step called ______ that goes from RNA-DNA
Reverse Transcription
Viral ______ splices (pop into human nucleus) viral DNA into host DNA
Integrase
How does HIV become AZT-resistant?
MUTATION (always happening)
T/F Reverse transcription can happen in cellular life?
False: It is specific to retroviruses
Enzyme that carries out reverse transcription _____
Reverse transcriptase
_____ fuses with host immune cell
Virion
What would happen if injected with purified RNA (just RNA, no viral proteins) from HIV?
Probably be fine because RNA alone cannot transcribe to DNA should not be threat to human health
AZT was a wonder drug at first because it successfully blocked
RT, once disease in cell, cant spread
Viral DNA gets _____,______ and forms new virions
Transcribed, translated
Difference btwn Thymidine and AZT-Triphosphate
Thymidine has OH attached while AZT-Triphosphate has N3
We can target what step of Virus
Reverse transcription
The drug AZT is a nucleoside analog shaped almost like ______
Thymidine (T)
____ stalls synthesis of DNA strand
AZT
After months of AZT treatment, HIV becomes _____: Can still synthesize ___ even when AZT present
resistant, DNA
The structure of susceptible vs resistant diffrence
resistant: subtle change in active site, shaped so cannot attach to AZT not fool
RT makes errors in copying HIV genome (mutations). A ____ fraction of mutations improve AZT (not all)
tiny
Unless there’s another mutation, susceptible virions replicate into ____ virions, resistant virions replicate into _____ virions
susceptible, resistant
Soon becomes genetic and _____ variation in the viral population
phenotypic
AZT treatment: susceptible viruses fail to ______
reproduce
Some variants are able to reproduce in the presence of AZT =______ HIV
drug resistant
_____ cause variation in AZT resistance
Mutations
AZT resistance passed from _____ to _____
Parents to offspring
T/F not all virions reproduce
TRUE: some more successful then others
IF and only if AZT is present, some forms (_______) are more likely to reproduce than others (_______)
AZT-Resistant (huge advantage), AZT-susceptible
Viral population _____ over time
changes (more and more resistant)
Variation + Non random survival =
Evolution by natural selection