Koch’s Postulates
The purpose of Koch’s postulates is to establish a connection between a pathogen and a disease.
The four postulates involved were proposed in 1884 by Robert Koch and are still used to this day.
The postulates are as follows:
Quick Questions:
Which piece of information is more impactful- a case of the disease where the expected
pathogen can be found or a case where the suspected pathogen cannot be found?
-
Why would it be more valuable?
Would a virus or a bacteria be easier to replicate in a lab?
-
Why would it be harder to replicate?
Practical Investigation
Aim: To demonstrate that the fungus growing on the surface of an apple is the cause of the apparent
disease in apples
Hypothesis:
Materials:
-
1x Symptomatic Diseased apple
1x healthy apple
1x Scalpel
1x box of Matches
1x Bunsen Burner
Sterilizing alcohol solution
10% bleach solution
2x agar plates
Tape
Permanent Marker
Method 1 Isolating and Culturing Pathogen:
https://youtu.be/-LtApkEunw4?t=66
Watch the above method, and convert it into an appropriate step by step written method below
Method 2 Inoculating Healthy Apple with Suspected Pathogen
https://youtu.be/ipsw28kET-I?t=67
Watch the above method, and convert it into an appropriate step by step written method below
Method 3 Re-isolation of Pathogen
https://youtu.be/fCUNlz-SAeU?t=43
Results:
Method 1:
What is the relevant data that needs to be collected from this step?
What are some good ways of recording it?
Do so below:
Method 2:
What needs to be compared to what at this point?
Record this comparison below:
Method 3:
What needs to be compared to what at this point?
Record this comparison below:
Evaluation:
What are some controls that worked well?
Were the results consistent across the class?
What are some reasons for these inconsistencies?
If you were to perform this experiment again what would you change about it to get more reliable
data?
Conclusion:
What can you conclude from this experiment? How definitively can you state this?