Help! Cellular Respiration!

Discussion of all aspects of cellular structure, physiology and communication.

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Help! Cellular Respiration!

Post by Khan » Sun Mar 12, 2006 4:45 pm

Hi..i'm a freshmen student in New York and i'm studying for a cellular respiration test. I've got a question about the electron carriers..NAD; FAD etc. I'm just confused what the difference between NAD and FAD is and why textbooks seem to say NADH is the same thing as FADH2..i mean, why doesn't NADH have 2 after the H like FADH2 does?

Could someone also explain to me what acetyl-coa is and what it does? I've got an idea that it's and enzyme or coenzyme but i cant figure out what kind of part it plays in cellular respiration. :?

i'd really appreciate if someone could explain this to me.


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Post by maria_geo » Sun Mar 12, 2006 5:03 pm

NAD acts as energy carrier in redox reactions but FAD is involved in tranferring electrons during glucose metabolism.

Acetyl-coA is a compound that reacts with oxaloacetate to produce citrate at the beggining of the citric acid cycle.

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Post by MrMistery » Sun Mar 12, 2006 6:36 pm

the main practical difference between NADH and FADH2 is that NADH produces 3 ATP(2.5-2.7 if you are a wise guy), giving it's electron to complex I, while FADH2 produces only 2 ATP(again, 1.5-1.7 if you are a wise guy) as it gives it's electron to complex II, located downstream of complex I in the electron transport chain.

About acetyl~CoA. After pyruvate is obtained by glycolysis it is activated with CoA. This is first done by removing the energy poor -COOH bonf from pyruvate and attaching the leftover acetyl bond to a Sulfur atom in the structure of CoA. This molecule, acety~CoA, then transforms the energy rich acetyl bond to oxaloacetate, turning it into citrate, and starting the Krebs cycle.

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Post by kiekyon » Mon Mar 13, 2006 3:41 am

NADH and FADH2 have the same function
only NADH does it better (producing more ATP)

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