antigens, antibodies & viruses

• HIV virus contains a capsid, lipid envelop, attachment protein, rna, reverse transcriptase
• Explain how antigen variability can be caused?

  mutation in DNA base sequences leads t a different sequence of codons in mRNA, changing the primary structure
• antigen variability can be caused by mutations in the dna/rna or by reassortment of genetic info inside host cell (caused by infection of more than 1 strain)
• Antigens - small proteins that stimulate an immune response 
• Antibody - quaternary protein (more than 1 polypeptide chain) secreted by plasma cells. They bind to antigens to form an antigen-antibody complex 
• Self antigens - receptors on the cell surface of own body cells 
• Toxins - byproducts from bacterial metabolism 
• where would you find antigens?

  surface of pathogens.

  abnormal/damaged body cells (cancer)

  cells introduced from other individuals.

  toxins
• HIV replication:

  HIV binds to attachment proteins on T-helper cell

  HIV injects viral RNA into T-helper cell

  enzyme reverse transcriptase converts the RNA to DNA and inserts this into t-helper cell's genome

  the DNA is translated and produces viral proteins which assemble new HIV particles
• • why antibiotics cannot be used to treat HIV:
  • Viruses are particles and not cells
  • They have no metabolism or cell structure (murein cell wall) for antibiotics to act on and disrupt