Cells - Cell recognition and the immune system - - HIV Flashcards Preview

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Flashcards in Cells - Cell recognition and the immune system - - HIV Deck (21)
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What does HIV stand for?

Human immunodeficiency virus


What does AIDS stand for?

Acquired Immune Deficiency Syndrome


Is it possible to catch AIDS? Why?

No. AIDS results from HIV which is contagious


When was AIDS first diagnosed?



What surrounds the HIV virus?

lipid envelope


What structures are embedded within the lipid envelope surrounding the viral cell?

attachment proteins


What layer is inside of the lipid envelope on an HIV virus?



What is inside of the capsid on an HIV virus?

RNA and some enzymes


What is the enzyme found within the capsid of the HIV virus?

Reverse transcriptase to make DNA from RNA using the host cells organelles.


The presence of the enzyme reverse transcriptase means that HIV belongs to which group of viruses?



How does HIV get its genetic information into its host cell?

- HIV enters the bloodstream and circulates
- A protein on the HIV binds to CD4 (a protein) found on helper T cells
- the HIV capsid fuses with the hose cell membrane
- the RNA and enzymes move from the HIV virus into the helper T cell
- the HIV reverse transcriptase converts the RNA into DNA.


How does HIV replicate in its host cell?

- the HIV reverse transcriptase converts the RNA into DNA.
- the new DNA moves into the hose cells nucleus and incorporates into the genetic material.
- protein synthesis occurs and the DNA is used to create mRNA.
- the mRNA passes out of the nuclear pore and undergoes protein synthesis to make new viral proteins.
- the new HIV viral cells break away from the helper T cells with a piece of the membrane around them to form their lipid envelope.


What happens to the immune system with no helper T cells?

helper T cells are important in cell mediated immunity. Without them B cells and cytotoxic T cells are not stimulated to kill pathogens. This means the body is unable to create an immune response to infection.


What are the common secondary infections suffered by HIV patients which often result in death?

infections of the lungs, intestines, brain and eyes, as well as weight loss and diarrhoea.


does HIV kill individuals directly?

No. The secondary infections cannot be fought off by the weakened immune system.


What does ELISA test stand for?

Enzyme Linked Immunosorbant Assay


What does ELISA test for?

Uses antibodies to detect the presence and quantity of a protein in a sample, even if the quantity is very small.


How does the ELISA test work?

- apply the sample to a surface to which all the antigens can attach.
- wash the surface to remove unattached antigens.
- add the antibody specific to your antigen and allow them to bind.
- wash the surface to remove unattached antibodies.
- add a second antibody that binds to the first, this antibody is associated with an enzyme.
- add a colourless substrate, which is complementary to the enzyme on the second antibody.
- an enzyme catalysed colour change will occur, the intensity of colour depending on the amount of antigen present.


Which diseases is the ELISA test used for?

HIV, TB and Hepatitis


Other that detecting diseases, what else is the ELISA test used to detect in the body?

Drug concentration in the body of athletes and other sports men and women.


Why are antibiotics ineffective against viruses?

Some antibiotics attack cell walls, which viruses (along with animal cells) to not have.
Cell walls are made from murein which is inelastic so prevents cell expansion when water moves in by osmosis. Antibiotics inhibit the enzymes needed to make cell walls, hence they expand and burst.

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