Anybody taking MicroBio?

[IzzieMonster]

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Ok everyone, I am at a loss. Please help if you can 🙁
This is a question from my HW, and I can't seem to figure it out...

"E. Coli and other enterics are obviously capable of aerobic respiration. How then, do thay manage to function without cytochrome c oxidase, the terminal complex in a chain of electron carriers used by many respiring organisms?"

 

[minoh87]

i think....
in human gut the environment that these microbes need to survive is most likely anaerobic. so these enteric microbes utilize anaerobic mechanisms to draw energy (i.e. fermentation and may be even using other electron acceptor than oxygen like sulfite or something..). Since aerobic respiration is nonessential to gut microbes survival cytochrome c oxidase is not required for bacteria's survival?

 

[healthcaree]

e.coli is a facultative anaerobe

 

[KillaCam]

Havent taken Micro in a while but from what I know, E. coli and other aerobic bacteria are not limited/confined to the usual case of using the well-known cytochrome c oxidase electron acceptor/carrier within the Electron Transport Chain (ETC) in the final/terminal step in reducing oxygen to make water. Rather, they have different oxidases that can accept the electrons (and thus have a high affinity for them, but less than that of oxygen of course!) and can pass them on to oxygen in a different manner than that of cytochrome c. In fact, the alternate terminal oxidases in these cases are essentially proton pumps that still produce the same end result-----oxygen getting reduced to become water.

In short, there are alternate oxidases that exist that can still perform the same end function but do so in a different mechanistic manner. It's amazing to think about the variety and ways molecules/enymes/complexes have evolved in order to carry out the same functions but in different paths energetically and mechanistically. Evolution is such an awesome power, yes?!

Hope this helps

 

[yappy]

Because they are facultative and are found in the gut where high levels of co2 are, I would suggest that like the above poster said they're not using a cytochrome C as the terminal electron accpetor; but rather, another form of metabolism (anaerobic). ??? What i'm saying is maybe they're using glycolysis and regenerating their NAD+ through a means different than entering a Krebs then ETC.

Your microbio sounds alot more interesting than mine... mine has zero problem solving and is memorizing one to two details about 100'S of bacteria, virus, and other organisms. More memorizing than antomy.

e.coli is a facultative anaerobe

 

[IzzieMonster]

Thanks all 🙂
I will compile everything you guys said, and try to come up with a short but sweet answer.

As far as 'more interesting'... I don't know about that. I wish it was a cut and dry course where all you had to do was learn a couple of things about 100's of microbes, but that's the case here. I feel like she makes this class up to graduate level standards... It is VERY challenging with a class average of 62%, and we only have 12 students in the class...