bacteria and virus

• structure of virus 


  smaller and simpler than bacteria

  have a nucleic acid enclosed by a protein coat
• viruses do not have the ability to reproduce and grow on their own so must enter a host cell
• viruses take over a cell and disrupt the normal cell activity
• how does a virus grow and replicate 


  attaches to host cell

  virus inserts nucleic acid

  the nucleic acid replicates

  viral protein coat is synthesised

  new virus particles form

  virus particles are released by cell lysis
• some viruses have an outer envelope taken by host's cell membrane
• an example of an enveloped virus is HIV
• what are the purpose of virus attachment proteins 


  used to bind to complementary receptor proteins on surface of host cells
• distinguish between the structure of bacteria and a virus 


  virus has a protein coat bacteria does not

  bacteria are cells virus are not

  bacteria have circular DNA while virus has linear or circular DNA