Table 1: Assay Results Filter Paper Section Colony Color Change? Oxidase Positiv
ID: 90717 • Letter: T
Question
Table 1: Assay Results
Filter Paper Section
Colony
Color Change?
Oxidase Positive or
Negative?
Exp. 1 skin
1
yellow to purple Purple
Positive
Exp. 2 shoes
1
Orange to yellow
negative
Exp. 3 phone
1
Yellow to purple
positive
Control
1
No color change
n/a
Insert pictures of your plates after incubation, and the results of the “DrySlide” for each of the plates below.
Post-Lab Questions:
Which bacterial plates contained oxidase positive bacteria? Which plates contained oxidase negative bacteria? Did both of the colonies from each plate show the same color change? Why or why not? How would you interpret this?
Which bacterial samples have cytochrome c oxidase as the terminal enzyme of their ETC? Which bacterial samples do not have cytochrome c oxidase as the terminal enzyme of their ETC?
3. Is the control test in this experiment positive or negative control? What is the purpose of a negative control?
4. What is the purpose of a positive control?
5. How are mitochondria in eukaryotic cells similar to bacteria that use aerobic respiration?
Table 1: Assay Results
Filter Paper Section
Colony
Color Change?
Oxidase Positive or
Negative?
Exp. 1 skin
1
yellow to purple Purple
Positive
Exp. 2 shoes
1
Orange to yellow
negative
Exp. 3 phone
1
Yellow to purple
positive
Control
1
No color change
n/a
Explanation / Answer
Answer:
1. Skin and phone contained oxidase positive bacteria. Shoes contained oxidase negative bacteria.
No. They all did not produce the same color because only the oxidase positive bacteria could use oxygen as terminal electron acceptor.
(Thr negative result of the control was due to no bacterial growth)
2. a. Skin and Phone have cytochrome c oxidase as the terminal enzyme of their ETC.
b. Shoes did not have cytochromes c oxidase as the terminal enzyme of their ETC.
3. Negative control, because there was no bacteria growth.
4. If there is positive control, then some bacteria may have grown from the other side of the petri dish or when use cotton swab it touched a bacteria surface.
5. Mitochondria use oxygen as their final acceptor to product ATP. Similar kind of mechanism are found in bacteria and perform anaerobic respiration.
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