Petri Dish investigation

1
Petri Dish investigation
2
agar

• A gelatinous material derived from certain marine
  algae.
• used as food for bacteria and as a thickener in
  many food products (carrageenan)

3
inoculate

• To introduce micro-organisms or infectious
  material into a culture medium.

4
The Clamshell method

• Turn the dish upside down when streaking to avoid
  germs from the air landing on the dish.

5
streak

• To make lines
• method of inoculating to make sure germs get
  all over the plate

6
Sterile

• Free from live bacteria or other
• micro-organisms
• a sterile
• operating area
• sterile instruments.

autoclave
7
Shape of bacterial cells

• Cocci - round bacterial cells.
• (cox-eye).
• b) Bacilli - rod-shaped bacterial cells.
• c) Spirilli (corkscrew) - spiral-shaped
  bacterial cells

A
B
C
8
QHEIC-the Scientific Method

• Question
• Hypothesis
• Experiment
• Interpret data
• Conclusion

9
Variables

• Independent Variables
• The factor that is purposely changed
• EX The different locations to be swabbed

• Dependent Variable
• The factor that you expect to change as a result
  of what you purposely changed.
• EX the amount of bacteria that grows

10
Procedure

• 1) Record the numbers of your dishes on your
  data chart and make sure the dishes are divided
  into A,B, C and D. Each group will get 1 dish.
• 2) Go to your first location and use your swab to
  gently rub the location. Rub the location for 10
  seconds.
• 3) Invert dish ,open quickly and streak the plate
  with the swab.
• 4) Repeat for other locations after discarding
  swab.
• 5) Remember to write down the location on your
  sheet.

11
The constants and the control

• Constants
• The factors that are kept the same in all trials
• Swabbing method
• Swabbing time
• Temperature of room

• Control
• the trial that is not exposed to the varying
  condition
• EX section D