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Cellular Respiration help

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Cellular Respiration help

Postby leftventricle » Wed Dec 01, 2010 4:26 am

I have a unit test on Cellular respiration in cells in like 3 days so I was just coming here to ask a few questions.

1) What is cAmp? I know it's Cyclic adenosine monophosphate and it's a type of ATP but what's its significance? Our teacher never went over this and I am curious.

2) Is heat generated in human cellular respiration along with ATP? I know the whole point of cellular respiration in phases is to have less waste comparative to a test tube combustion of glucose...so does that mean no heat is generated?

3) Which phases require O2 in cellular respiration?
Glycolysis doesn't, but why? Because it's in the cytoplasm....I think but I can't explain anymore.
Pyruvate oxidation does? I would assume so since it's in the name.
What about Krebs?
ETC obviously does...since it's the greatest oxidizing agent for the electrons through the transport proteins.

I also heard that lactic acid can be formed if you don't have sufficient O2 when working out for your cells to use and thus you feel pain if you haven't breathed properly during your workout.

4) AND WHAT THE HECK IS THIS "coASH" business...I know if I studied that section a bit more I may be able to understand it but...it's still cconfusing.
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Postby JackBean » Wed Dec 01, 2010 10:21 am

1)
i) it's cAMP
ii) it's cyclic adenosine MONOphosphate, so it can NOT be a type of adenosine TRIphosphate :roll:
iii) it functions as so called second messanger AKA substance produced by the cell after trigering receptor by binding of some ligand. Look into some regulations of metabolism, I'm pretty sure you will find plenty of informations

2) no, the efficiency is not 100% and you should be able to calculate the efficiency as you know the G0 of Glc and ATP and you know how many ATPs are produced...

3)
glycolysis - so, because the pathway is in cytosol, it does not use oxygen, but other pathway, which is localised in mitochondrion surrounded with cytoplasm, can use oxygen? What logic is that?
pyruvate oxidation - you can oxidase with anything, not only oxygen. How is the enzyme exactly named?
Krebs - well, this is tricky one. It does not use directly oxygen, but does not run anaerobically, because it needs the cofactors, which are regenerated in ETC only by use of oxygen. What bring us to the lactic acid: if you do not have enough oxygen, the TCA cycle (and ETC of course) stops, but the glycolysis is still running (you need to take the energy from somewhere...), but even glycolysis needs some cofactors. And these are regenerated by reduction of pyruvate to lactate.
ETC - yes, but your reasoning is wrong again

4) It's CoA AKA coenzyme A which has sulhydryl group (-SH) and that's the reason, why is it sometimes writen as CoASH (or CoA-SH), especially, when you do not want to write the complete formula (it's quite long and complicated), but you need to put it into some equation. I'm sure that with these informations you will be able to study more, because these are the biochemistry basics, which you REALLY should know!
http://www.biolib.cz/en/main/

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Postby leftventricle » Sun Jan 02, 2011 9:24 am

Thanks for answering my questions!

But since the efficiency is not 100%, where is the heat going inside your cells?

And for ETC - the reason that it needs oxygen is because oxygen is required to reduce the electrons from the cofactors (NADH, FADH2) and thus the cofactors can be recycled back to mitochondria for Kreb's cycle?

But for glycolysis - the carriers are different (ie the NAD+ is cytoplasmic) and has no relation to the ETC, thus can still occur without oxygen?
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Postby jmm » Mon Jan 03, 2011 3:32 am

The heat generated is what keeps your body from freezing.
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Re:

Postby JackBean » Tue Jan 04, 2011 4:49 pm

leftventricle wrote:But since the efficiency is not 100%, where is the heat going inside your cells?

As said, it's lost as heat.

leftventricle wrote:And for ETC - the reason that it needs oxygen is because oxygen is required to reduce the electrons from the cofactors (NADH, FADH2) and thus the cofactors can be recycled back to mitochondria for Kreb's cycle?

Not really, that's the reason, why TCA cycle is oxygen-dependent, although the oxygen is not involved at all. But regarding ETC its simply because w/o oxygen it gets fastly saturated with electrons and simply stops

leftventricle wrote:But for glycolysis - the carriers are different (ie the NAD+ is cytoplasmic) and has no relation to the ETC, thus can still occur without oxygen?

Could be. The point is, there is high enough capacity to reoxidize the coffactors by lactate dehydrogenase. However, when there is enough oxygen, the electrons are shuttled to mitochondria as well.
http://www.biolib.cz/en/main/

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