MESS BK experiment

Background information

  1. t-4 phages kills e.colli bacterium
  2. Hypothesis: The e.colli will not become resistant to t-4 phages (null hypothesis)…proven false by ONE colony appearing.
  3. Proven False
  • How did the e.colli become resistant?
    • (null) Ho: It just happens randomly. (random mutations by chance).
    • (alternative) Ha: It is caused by exposure to t4. (exposure to t4 makes some e.colli able to resist).

DAY ONE

Robson took one colony of E.Colli bacteria off a plate of bacteria with a sterile (can't remember name) and inoculated the sterile broth in a flask (which ended up turning cloudy meaning there was growth of the E.colli bacterium. She took that same colony and inoculated a tube full of t-4 phages (which ended up being clear meaning the bacteria was killed by the t-4 phages).

  1. These both were incubated for 24 hours then the flask put into a 1/50,000 dilution of broth culture.
  2. Robson then took 200 test tubes and inoculated them with .5mL of the bacterium dilution broth mixed with 5 mL of sterile broth.
    • half of the test tubes were inoculated in shaking racks and the other half were inoculated in a stable (non shaken) environment.
  3. from the flask of 1/50,000 dilution she also inoculated one flask with 500 mL of sterile broth mixed with 50 mL of bacteria solution.
  4. Then let all these solutions incubate for 24 hours ???

DAY TWO
what we did…

  1. LABEL

* Label 30 with name: MESS BK
* Label 10 serial dilution or "no t-4"
* Label 20 t-4
* Label 10 "Tube 1" thru "Tube 10""
* NOTE:
* Tubes 1-5 were "Shaken"
* Tubes 6-10 were "Still"
* Label the other 10 "Flask"

  1. PIPETTING!!!
  • Flask:
    • Pipet .1 mL out onto ten plates label "flask" then hockey stick…
      • Note: you can use the same pipet.
  • Tube:
    • Pipet .1 mL out of individual tubes onto separate plates then hockey stick. (One tube per plate).
      • Note: You have to use a different pipet for each tube.
  1. SERIAL DILUTION!!!

Same technique used for first lab.

  • We took the "not t4" and had 5 sterile dilutions from the flask and then 5 from a nonshaken flask.
    • On both dilutions we went from 1/10^6 to 1/10^10

QUESTIONS

1. If the null hypothesis is true, how should the number of resistant colonies from the tubes compare to those from the flask? Why?

  • Answer: The number of resistant colonies in the test tubes will not correlate, meaning there will be numbers at extreme opposite ends, while the test tubes will be closely related and show some sort of relationship.

2. If the Alt. hypothesis is true, how should the number of resistant colonies from the tubes compare to those from the flask? Why?

  • Answer: Both the flask and the tubes will have closely related data.

RESULTS

  1. "NO T-4"
  • TEST TUBES
    • 10^6: "37"
    • 10^7: "5"
    • 10^8: "0"
    • 10^9: "0"
    • 10^10: "0"
  • "FLASK"
    • 10^6: 27
    • 10^7: "3"
    • 10^8: "1"
    • 10^9: "0"
    • 10^10: "0"
  1. "Shaken T-4"
    • Tube 1: 135
    • Tube 2: 525
    • Tube 3: 225
    • Tube 4: 75
    • Tube 5: 265
  1. "Still T-4"
    • Tube 6: 2,000
    • Tube 7: 13,000
    • Tube 8: 1,500
    • Tube 9: 15,000
    • Tube 10: 1,100
  1. "NO T-4 Flask"
    • 8,000 (5)
    • 9,000 (2)
    • 6,000 (2)
    • 7,000

RESULT —> RANDOM MUTATION!!!!

SORRY I spelled E.COLI wrong. All e.colli need to be changed to E.COLI!!!

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