Life Cycle - Human Biology (6B)

  • Distinguishing viruses and bacteria.
  • Distinguishing inherited characteristics.
  • bacteria
  • vaccine
  • virus
  • worksheet on viruses/bacteria

Students sort bacteria and viruses.



Bacteria come in three different shapes: (1) coccus or sphere shaped; (2) bacillus or rod shaped; (3) spirillum or spiral, corkscrew shape.  Bacteria have a tough outer coating which gives them a cell-like shape.

Viruses are non-living and cannot reproduce without using the mechanisms of a host cell. Once a virus enters a host it can cause great damage.  Viruses come in different shapes.  Viruses are smaller than bacteria, have no nucleus, no cytoplasm, and no surrounding cell membrane. There are, however, some viruses, that produce a "fake" cell membrane that is used in tricking the immune system.  Actually, a virus can almost be considered a chemical crystal.

Bacteria and viruses that cause disease are called pathogens.  Pathogens can enter a body through the air, water, or through contact with an infected body.  Diseases caused by bacteria can usually be cured with medication.  Viral diseases on the other hand cannot be cured because there is no medication that will stop viruses.  The immune system of the human body has to fight the viruses, sometimes the body wins but many times it loses.  Vaccines can help prevent the virus in the first place.  Viruses are very difficult to study.

  1. Go over the characteristics of bacteria and viruses using the student's lab sheet. 
  2. Instruct the students to cut out the viruses and bacteria and try and sort them into their respective groups.  Tell students to write their answer on the back site of each picture with the reason for the student putting it in its group.  This is not an easy lab, because the weird shapes that both bacteria and viruses take.
  3. The bacteria and viruses on the chart are: 
  1. phage, a virus that invades the cells of bacteria
  2. Influenza virus, causes influenza
  3. generalized mycoplasma (bacteria)
  4. tobacco mosaic virus, results in disease of tobacco plants
  5. smaller tobacco mosaic virus
  6. micrococcus radiodurans (bacteria)
  7. spirillum bacteria
  8. crystal of adenovirus particles within the nucleus of a human cell
  9. polio virus
  10. bacillus bacteria
  11. tumor virus
  12. pseudomonad bacteria
  13. prochloron bacteria
  14. spirillum bacteria
  15. cell invaded by bacillus bacteria
  16. influenza virus.

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