5.7 - HIV

• What structure is on the outside ?

  Lipid envelope
• What structures are embedded in the lipid envelope ?

  Attachment proteins
• What is the protein layer inside the envelope called ?

  Capsid
• What genetic material is found in the capsid ?

  RNA
• What enzyme is found in the capsid ?

  Reverse transcriptase
• What does the reverse transcriptase do ?

  Catalyses the production of DNA from RNA
• 1st step when HIV replicates in T helper cells ?

  Protein on HIV binds to receptor on t helper cells called CD4
• 2nd step when HIV replicates in helper T cells ?

  Capsid fuses with cell membrane and RNA and enzymes enter the helper T cell
• 3rd step when HIV replicates in helper T cells ?

  HIV reverse transcriptase converts RNA to viral DNA
• 4th step ?

  DNA is inserted into helper T cells DNA and transcribed into mRNA
• 5th step ?

  The cells protein synthesis mechanisms make HIV particles which break away from the helper T cell , taking a bit of cell-surface membrane to form their lipid envelope
• How does HIV cause AIDS ?

  Killing or interfering with the normal functioning of helper T cells
• Without a sufficient number of helper T cells what two thipangs can the immune system not produce ?

  B cells therefore antibodies and cytotoxic T cells
• What does ELISA stand for ?

  Enzyme-Linked Immunosorbent Assay
• What does the ELISA test do ?

  Detects antibodies or antigens
• 1st step of an elisa ?

  Add sample to reaction vessel so antigen binds
• 2nd step of elisa ?

  Wash to remove any unattached antigens
• 3rd step of an elisa ?

  Add blood plasma sample with specific antibody and leave them to bind
• 4th step of an elisa ?

  Wash to remove unbound antibodies
• 5th step of an Elisa ?

  Add second antibody that has an enzyme attached
• 6th step of an Elisa ?

  Wash to remove unbound secondary antibodies
• 7th step of an Elisa ?

  Add substrate complementary to the enzyme
• Result of a positive Elisa test ?

  A coloured precipitate
• 3 reasons why antibiotics ineffective against viral diseases ?

  No cell structures for them to disrupt, no murine cell wall so no sites where antibiotics can work, within a cell so antibiotics can’t reach them