CELLS: HIV and Viruses Flashcards
What does HIV stand for?
Human Immunodeficiency Virus
What is HIV?
A virus that affects the immune system.
If untreated, what can HIV progress to?
AIDS.
What is AIDS?
Acquired immune deficiency syndrome.
Briefly, what is AIDS?
A condition that progresses from HIV, where the immune system deteriorates and eventually fails.
What causes AIDs?
Untreated HIV
What does the capsid of HIV enclose?
Two single strands of RNA and some enzymes.
Give an example of one of the enzymes enclosed within the capsid of HIV:
Reverse transcriptase.
What is reverse transcriptase?
An enzyme found within the capsid of HIV that catalyses the production of DNA from RNA.
What group of viruses does HIV belong to?
Why is this?
Retroviruses.
Due to the presence of reverse transciptase inside of its capsid, meaning it has the ability to make DNA from RNA.
Draw a HIV particle:
Why are helper T-cells important in the immune system?
They send chemical systems that activate phagocytes, cytoxic T-cells and B-cells.
Without enough helper T-cells, the rest of the immune response can not begin.
When do people with HIV develop AIDS?
When the helper T-cells numbers in their body reach a critically low level.
What is contained within the core of HIV?
Genetic material and some proteins.
What is the capsid?
The outer coating of protein surrounding a HIV particle.
What is the outer coating of protein surrounding HIV known as?
A capsid.
What is the extra outer layer on a HIV virus called?
An envelope.
On a HIV particle, what is the envelope?
The extra outer layer.
In HIV, what is the envelope made of?
The membrane stolen from the cell membrane of a previous host cell.
What do attachment proteins help HIV to do?
Helps HIV attach to the host help T-cell.
What is found on the envelope of the HIV particle?
Attachment protiens.
What can attachment proteins also be called?
Envelope proteins.
How does HIV replicate?
- Attachment protein attaches to receptor on host helper T-cell
- Capsid released into cell = uncoats + releases RNA into cytoplasm
- Reverse transcriptase makes complementary DNA strand
- Double stranded DNA is made + inserted into human DNA
- Host cell enzymes make viral proteins from viral DNA found in human DNA
- Viral proteins assembled into new viruses which bud from cell
Latency period
Time after HIV infection where a person won’t experience symptoms.
Where does HIV replicate?
When does HIV move to aids?
When helper T-cell counts falls below a certain level
What are the initial symptoms of AIDs?
Minor infections of mucous membranes
Recurring respiratory infections
What can develop during the late stages of AIDs?
Toxoplasmosis of the brain
Candidiasis of respiratory system
How do antibiotics kill bacteria?
Interfer with metabolic reactions.
Particularly targeting bacterial enzymes and ribosomes.
Why can’t antibiotics work for viruses?
- Viruses don’t have own enzymes and ribosomes, so use human ones
- Antibiotics can’t inhibit as don’t target human processes
What are used to treat viruses?
Antiviral drugs target the few virus-specific enzymes
Is there a cure for HIV?
No, but antiviral drugs can be used to slow down progression.
