The Human Immunodeficiency Virus Flashcards
What does HIV stand for?
Human immunodeficiency virus
What disease does HIV cause?
Acquired Immune Deficiency Syndrome (AIDs)
What is the outermost layer of HIV called, and what is embedded in it?
The lipid envelope, with peg - like attachment proteins embedded in it
What is the protein layer inside the lipid envelope called?
The capsid
Name an enzyme found inside HIV and its function
Reverse transcriptase, which catalyses the production of DNA from RNA
What does the capsid enclose?
Two single strands of RNA and some enzymes
Why is HIV classified as a retrovirus?
This is because it contains reverse transcriptase, which allows it to produce DNA from RNA
Why can’t HIV replicate itself?
HIV is a virus, so it lacks its own cellular mechanisms. so it uses the host cell’s biochemical mechanisms to replicate
What does HIV bind to on host cells?
A protein called CD4, which is most commonly found on helper T cells
How does HIV enter a helper T cell?
The protein capsid fuses with the cell - surface membrane, allowing RNA and enzymes to enter the cell
What enzyme does HIV use to convert its RNA into DNA?
Reverse transcriptase
Where does the newly made viral DNA go after being formed?
It is inserted into the host cell’s DNA inside the nucleus
How does HIV use the host cell to produce new viruses?
The HIV DNA in the nucleus produces mRNA, which is used to make viral proteins and RNA for new HIV particles
How do new HIV particles leave the infected helper T cell?
They “bud off, taking a piece of cell - surface membrane, which forms their lipid envelope
What does it mean if someone is HIV positive?
They are infected with HIV, but the virus may be dormant for years before causing AIDs
Outline the steps of how HIV replicates (8 steps)
1) HIV enters the bloodstream and circulates around body
2) Proteins on the HIV readily bind to a protein called CD4
3) The protein capsid fuses with the cell surface membrane, so the RNA and enzymes of the HIV enter the helper T cell
4) The HIV’s reverse transcriptase converts the virus’s RNA into DNA
5) The newly made DNA, moves into helper T cell’s nucleus, so it is inserted into cell’s DNA
6) The HIV’s DNA in the nucleus creates messenger RNA (mRNA), using the cell’s enzymes. This mRNA contains instructions for making new viral proteins and RNA to enter new HIV
7) mRNA passes out of the nucleus, through the nuclear pore and uses the cell’s protein synthesis mechanisms to make HIV particles
8) HIV particles break away from helper T cells with a piece of its cell - surface membrane surrounding them, which forms their lipid envelope
