From the TCA cycle we know:
1. Each molecule of pyruvate yields 3 NADHs and 1 FADH2 (coenzymes) for every cycle
2. …Because glucose is split into two pyruvates, one molecule of glucose gives: 6 NADHs+2 FADH2s.
Glycolysis, and the link reaction give us 2 ATPs, 2 NADHs & 2 NADHs repectively. The TCA Cycle doesn’t produce much energy (Net ATP= 2) so it’s safe to say that the TCA cycle produces these coenzymes to produce energy in the ultimate, energy mother lode… the Electron Transport Chain!!!.
On average, the ETC produces *drumroll please* 34 molecules of ATP…
Where do the NADHs and FADH2s from the TCA Cycle fit in?
They’re electron donors, basically they give these electrons to electron carriers, such as cytochromes, FMN, and coenzyme Q which make up the electron transport chain. This all happens in the inner membrane of the mitochondria and involves reducing O2 to H20 with the last cytochrome in the ETC, cytochrome.
Proton and electron transport are a dream-team, together they pump electrons along a chain of channel proteins which swap these electrons to send protons to the outer compartment of the mitochondria.
However, this buildup of protons (forming an electrical, and pH gradient) doesn’t last very long. The restless, energetic protons re-enter the matrix of mitochondria through the inner mitochondrial membrane via the enzyme ATP synthase resulting in ATP synthesis. For every NADH apprx. 3 ATPs are produced along with 2 ATP’s per FADH2…
That’s how we get those 34 ATP’s folks! (Harvey and Ferrier 2011).
If that didn’t sink in… well… there’s these pieces of awesomeness right here. Pretty sure this “Thrift Shop” parody and “Oxidate It Or Love It / Electron to the Next One” were made to be my geeky Biochem survival guide.
Harvey, Richard A and Denise R Ferrier. Lippincott’s illustrated reviews, biochemistry. Philadelphia: Wolters Kluwer Health, 2011.
Lam, Wilson. “TCA (Kreb’s) Cycle Rap – Wilson Lam (Macklemore – Thrift Shop Parody).” Digital video, 2013. https://www.youtube.com/watch?v=aMBIs_Iw0kE (accessed 22 March 2014).
Mcfadden, Tom. “Oxidate It Or Love It / Electron to the Next One.” Digital video, 2013. https://www.youtube.com/watch?v=aMBIs_Iw0kE (accessed 22 March 2014).