Lab Exam 2 Flashcards
What are Koch postulates?
- Diseased organisms are diseased while healthy individuals are healthy
- Disease must be isolated and grown in the lab
- Inoculate a healthy host with the cultured disease to see if it causes the same disease
- reisolate disease and see if it is the same as original disease
What type of bacteria did we try to isolate from the yogurt?
Streptococcus thermophilus
Why did we only use 1 single colony of bacteria to inoculate in to the tube of milk?
To see if the “disease” yogurt will cause the same disease in the healthy (milk)
Why was it important to use only one type of colony to work with when viewing under the microscope?
To ensure we are looking at the same pathogen that is causing the disease
What is Koch postulates used for?
To determine the causative pathogen in animals, humans, and plants
Characteristics of healthy state milk
- no smell, liquid, white w/ ph of 6.2
Characteristic of diseased yogurt
- sour like smell, thick, white and ph of 4.0
What did the inoculation of milk do to it?
Caused it to become diseased - turned into yogurt
What characteristics (physical/chemical) cause a diseased and healthy individual different?
Color, smell, texture, ph
What could be done using modern technology to find out for sure that the same bacteria inoculated is the same bacteria causing the disease?
Sequence them!!
Take the diseased original and the inoculated disease and sequence the genome to see if the are the same pathogen
How did we know the reisolated bacterium was the same as the original bacterium causing disease?
They has the same color, consistency, ph and smell
(Same characteristics)
What are the 3 forms of physical media
Solid , semi solid and broth
What are the 2 types of chemical forms of media
Complex media & chemically defined media
Complex media
Media (nutrient broth & niftiest agar) that is enriched with yeast extract or beef extract
What is complex media used for?
Routine lab works to provide food for heterotrophic bacteria
Chemically defined media
More specific!!
Media with known amount of chemicals used
What is chemically defined media used for?
Grow organisms that require special requirements or exclude certain organisms
What are the 3 special purpose medias types.
Selective, differential and enriched media
Selective media
Suppress the growth of unwanted bacteria by encouraging growth of wanted bacteria
Differential media
Allows to distinguish between 2 different bacterial species growing
More physical!
Enriched media
Contain nutrients to Favor the growth of a certain bacteria
Example of selective media
MacConkey agar
Example of enriched media
Blood agar and chocolate agar
Differential media example
Blood agar