Virus

• What do viruses have on their outside that allows them to attach to host cells?

  Attachment proteins
• Why are RNA viruses considered not living?

  Because they can't reproduce on their own
• What is the size range of viruses?

  20 nm to 300 nm
• What is the function of the protein coat in viruses?

  It protects the nucleic acid
• What type of genetic material do viruses use?

  DNA or RNA
• What does it mean for a virus to become latent during the lysogenic cycle?

  It means the virus has stopped reproducing viral particles
• What can reactivate a dormant virus?

  Various factors, including stress
• What happens during the lytic cycle of a virus?

  The host cell bursts, releasing new viral particles
• What is a retrovirus?

  A virus that contains RNA and converts it to DNA
• How does HIV affect the immune system?

  It decreases the number of helper T cells
• What is the role of reverse transcriptase in HIV replication?

  It converts viral RNA into DNA
• What happens to the body when the immune system becomes less efficient due to HIV?

  The body becomes more susceptible to infections and diseases
• What is the function of glycoproteins in HIV?

  They act as attachment proteins
• What is the process of HIV replication once inside a helper T cell?

  RNA is converted into DNA, which is then transcribed into mRNA
• What are the steps in the viral replication cycle of HIV?

  1. Attachment to host cell via glycoproteins
  2. Injection of nucleic acid into the host cell
  3. Reverse transcription of RNA into DNA
  4. Integration of viral DNA into host genome
  5. Transcription of viral DNA into mRNA
  6. Translation of mRNA into viral proteins
  7. Assembly and release of new viral particles
• What is the role of antibodies in an ELISA test?

  They bind complementary to antigens
• What happens during the washing steps of an ELISA test?

  Unbound antibodies are removed
• What does a color change in an ELISA test indicate?

  It indicates the presence of antigen
• What are monoclonal antibodies?

  Antibodies with the same tertiary structure
• what is the virus life cycle?

  1:virus binds to host cell using attachment proteins and viruses have different attachment proteins so different virus infects different types of cells.

  2:injection of nucleic acid and starts the lysogenic cycle

  3:the virus then hijacks the host cells machinery in order to replicate the viral genomes and to make new protein. Viruses can force the cell to give up using energy to make proteins and replicate dna for the cell and instead make viral protein

  4:cell bursts
• What happens when viruses mutate?


  When viruses mutate the viral gene(dna) also mutates changing the tertiary structure of the attachment protein allowing it to bind and infect other things it may have not been able to infect.
• How do viral particles leave the host cell?


  They bud off and use the cell membrane to form and envelope causing lysis of the cell
• How is hiv replicated in a helper T cell 


  RNA is converted into DNA through reverse transcription, DNA inserted into helper T cell genome, DNA transcribed into HIV mRNA, HIV mRNA translated into viral proteins
• Elisa test method?


  Enzyme-linked immunosorbent assay

  1 sample is on slide, add specific antibody to sample then wash

  2 2nd antibody binds to first antibody then wash, enzyme reaction happens,resulting in colour change
• Why do you wash after adding antibody to sample in Elisa test?


  It removes any unbound antibody
• What is a monoclonal antibody


  Antibodies with the same tertiary structure
• What’s the role of antiboldies in elisa test?


  antibody binds to complementary antigen,antibody with enzyme attached is added, antibody attaches to antigen and the colour changes.
• What are the 3 stages when a virus bind in succession?

  • low affinity receptor:in high abundance,virus contacts cell surface
  • Primary receptor:in lower concentration
  • Co receptor:follows binding of primary receptor
• What is uncoating?


  Separation of the nuclei acid from the caspid and happens to get the viral nuclei acid ready for expression
• Explain the process of budding?


  Viral proteins integrate into the host cell membrane and the viral nucleocaspid pushes against the modified membrane and the host membrane wraps around the viral nucleocaspid forming a bud. The hud pinches from the host cell membrane releasing the viral particle into the extracellular space.
• Uses of monoclonal antibodies?

  • Direct therapy- monoclonal antibodies that are specific to antigens found on the surface of cancerous cells can be used to target and then destroy the cells as part of an immune response
  • Indirect therapy- drugs can be attached to monoclonal antibodies such as a cytoxic. The antibody then is used to direct therapy drug towards the cells displaying a particular antigen
  • Diagnosis- particular antigens are targeted by antibodies to measure levels of that antigen in the body