5.7- THE HUMAN IMMUNODEFICIENCY VIRUS (HIV) Flashcards
What does the human immunodeficiency virus cause?
disease acquired immune deficiency syndrome (AIDS)
What is on the outside of the HIV structure?
lipid envelope embedded in which are peg-like attachment proteins
What is inside the lipid envelope of the HIV virus?
protein layer called capsid
What does the capsid of the HIV virus enclose?
two single strands of RNA + some enzymes
What is one of the enzymes that is enclosed in the capsid of the HIV virus?
reverse transcriptase
Why is reverse transcriptase so-called?
it catalyses the production of DNA from RNA- reverse reaction to that of transcriptase
What group of viruses does HIV belong to?
retroviruses
Why does HIV belong to the group retroviruses?
presence of reverse transcriptase + consequent ability to make DNA from RNA
As HIV is a virus can it replicate by itslef?
no
As HIV is a virus and cannot replicate by itself, what does it do?
uses its genetic material to instruct host cell’s biochemical mechanisms to produce components required to make new HIV
How HIV replicates: what does HIV do following infection? (1)
HIV enters bloodstream + circulates around body
How HIV replicates: what does a protein on HIV do? (2)
protein on HIV readily binds to protein called CD4
while this protein occurs on number of different cells, HIV most frequently attaches to T helper cells
How HIV replicates: what does the protein capsid do and then what happens? (3)
protein capsid fuses with cell-surface membrane
RNA + enzymes of HIV enter helper T cell
How HIV replicates: what does the HIV reverse transcriptase do? (4)
HIV reverse transcriptase converts virus’s RNA into DNA
How HIV replicates: where is the newly made DNA moved into? (5)
newly made DNA moved into T helper cell’s nucleus where it’s inserted into cell’s DNA
How HIV replicates: what does the HIV DNA in the nucleus create? (6)
HIV DNA in nucleus creates messenger RNA (mRNA) using cell’s enzymes
What does the mRNA produced by the HIV DNA in the nucleus contain?
instructions for making new viral proteins + RNA to go into new HIV
How HIV replicates: where does the mRNA from the HIV DNA pass out of and do? (7)
passes out of nucleus through nuclear pores + uses cell’s protein synthesis mechanisms to make HIV particles
How HIV replicates: what does the HIV particles break away from? (8)
HIV particles break away from helper T cell with piece of its cell-surface membrane surrounding them which forms their lipid envelope
What is a person said to be once infected with HIV?
HIV positive
What does the replication of HIV often do and then what happens?
often goes into dormancy + only recommences, leading to AIDS, many yrs later
What does the HIV virus specifically attack?
helper T cells
How does HIV cause AIDS?
by killing or interfering with normal functioning of helper T cells
Between how many helper T cells does an uninfected person normally have in each mm3 of blood?
normally has between 800 to 1200 helper T cells in each mm3 of blood
