The Human Immunodeficiency Virus Flashcards
What’s the enzyme in HIV
Reverse transcriptase - it catalyses the production of dna from rna
How does HIV replicate
1) attachment protein attaches to a receptor molecule on the cell membrane of the the host helper T cell
2) The capsid is released into the cell, where it uncoats and releases the genetic material (rna) into the cells cytoplasm
3) Inside the cell, reverse transcriptase is used to make a complementary strand of DNA from the viral RNA template
4) From this, double-stranded DNA is made and inserted into the human DNA.
5) Host cell enzymes are used to make viral proteins from the viral DNA found within the human DNA.
6) The viral proteins are assembled into new viruses, which bud from the cell and go on to infect other cells.
How does HIV cause the symptoms of aids
By killing or interfering with the normal functioning of helper T cells.
They are important in cell mediated immunity. Without a sufficient number of T helper cells, B cells will can’t be stimulated to produce antibodies or the cytotoxic T cells that kill cells infected by pathogens.
Memory cells are also destroyed so unable to produce an adequate immune response
Describe the ELISA test
Add sample to a surface
Wash surface to remove any unattached antigens
Add the antibody that is specific to the antigen we are trying to detect and leave the two to bind together
Wash the surface to remove any excess antibody
Add a second antibody that’s complimentary to the first ( this second one has an enzyme on it)
An enzyme substrate is added
The enzyme substrate reacts with the enzyme
It causes a colour change that is proportional to the amount of antigen present
How do antibiotics work
Water constantly enters cell by osmosis.
This would normally cause cell to burst
Wall is made of murein (not easily stretched)
Antibiotics inhibit enzymes rehired for the synthesis and assembly of the peptide cross linkages in bacterial cell walls. This weakens the walls making them unable to withstand the pressure. As water enters naturally by osmosis, the cell bursts and the bacterium dies
Why are antibiotics ineffective in viruses
As there are no metabolic mechanisms or cell structures for them to disrupt
They also have a protein coat so do not have sites where antibiotics can work
Explain why is HIV called a retrovirus
It posses rna and the enzyme reverse transcriptase which can make dna from rna - a reaction that is reverse of that carried out by transcriptase
