5.7 HIV

Question 1

how HIV causes symptom of AIDs

Answer 1

• kills or interfere with helper T cells

- without them cannot stimulate B cells to produce antibodies or Tc cells that kill infected pathogens

Question 2

the ELISA test

Answer 2

• apply the sample to a surface
• wash the surface => removes unattached antigens
• add specific antibody we are trying to detect
• wait
• wash surface => removes unattached antibodies
• add 2nd antibody => binds to 1st antibody and have enzyme attached
• add colourless substrate => enzyme changes it into a coloured product
• amount of antigen present is relative to the intensity of colour that develops

Question 3

why antibiotics are ineffective against viral diseases like AIDS

Answer 3

• inhibit certain enzymes required for the synthesis and assembly of the peptide cross- linkages in bacterial cell walls
• so can undergo osmotic lysis
• no metabolic mechanisms or cell structures for them to disrupt as they rely on host
• murein wall so do not have sites where antibiotics can work

Question 4

replication of the human immunodeficiency virus

Answer 4

• attaching to their host
• protein capsid fuses with the cell- surface membrane
• RNA and enzymes enter host cell
• HIV reverse transcriptase RNA-> DNA
• DNA moves into host cell’s nucleus
• DNA-> mRNA
• mRNA-> HIV particles
• HIV breaks away with a piece of its cell- surface membrane which forms their lipid envelope