Structure of prokaryotic cells and viruses

• What are 3 features of a typical prokaryotic cell?

  • small (0.1-10 micrometres) and a simple structure
  • have no distinct nuclei
  • no membrane bound organelles
• What are some extra features in some bacteria?

  • flagella - for movement
  • pili - hair like projections for attachment to surfaces and exchange of genetic material between bacteria
  • plasmids - smaller circular pieces of DNA
• Features of plasmids (4)

  • possesses genes that may aid the survival of the bacterium - e.g antibiotic resistance
  • can copy themselves independently of the chromosome
  • bacteria can transfer plasmids between other bacteria
  • they can loose them - when a bacteria divides the daughter cell may not end up with them
• What are 8 features of a prokaryotic cell

  • no true nucleus
  • DNA is circular - not associated with proteins
  • No membrane bound organelles
  • Smaller ribosomes (70s)
  • Cell wall made of murein
  • Has an outer layer called a capsule
  • Cytoplasm present
  • Cell membrane present
• Give some common features of HIV

  • genetic material - RNA
  • Attachment proteins
  • capsid
  • lipid envelope
  • matrix
  • enzymes (reverse transcriptase in HIV)
• How does a virus replicate?

  • virus attaches to host cell via receptors on the host cells cell surface membrane
  • The virus injects its genetic material into the host cell and this is used to synthesise viral proteins
  • The new virus particles are assembled
  • New viruses burst out of and damage/destroy host cell
• What is a virus?

  Acellular and non-living