Discussion of all aspects of biological molecules, biochemical processes and laboratory procedures in the field.
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a. When three molecules of pyruvic acud are broken down completely to CO2 and H2O in the presence of oxygen, how many molecules of ATP will be produced?
b. When one acetyl Co-A molecule is respired through the Kreb's Cycle and the electron transport chain to oxygen, how many ATP molecules will be produced?
THANKS for any help!
The electron transport chain takes place in the inner mitochondrion membrane. It follows the citric acid cycle, where NADH and FADH2 are reduced. These coenzymes then enter the electron transport chain. The first step is the transfer of high-energy electrons from NADH+H+ to FMN, the first carrier in the chain. From each molecule of glucose, two NADH+2H+ are generated from glycolysis, two from the formation of acetyl-CoA, and six from the citric acid cycle. In this transfer, a hydride ion H- passes to FMN, which then picks up an additional H+ from the surrounding aqueous medium. As a result, NADH+H+ is oxidized to NAD+, and FMN is reduced to FMNH2.
In the second step in the electron transport cahin, FMNH2 passes electrons to several iron-sulfur centers and then to coenzyme Q, which picks up an additional H+ from the surrounding aqeous medium. As a result, FMNH2 is oxidized to FMN.
The next sequence in the transport chain involves cytochromes, iron-sulfur clusters, and copper atoms located between coenzyme Q and molecular oxygen. Electrons are passed successively from coenzyme Q to cytochrome b, to Fe-S, to cytochrome c1, to cytochrome c, to Cu, to cytochrome a, and finnally to cytochrome a3. Each carrier in the chain is reduced as it picks up electrons and is oxidized as it gives up electrons. The last cytochrome, cytochrome a3, passes its electrons to one-half of a molecule of oxygen, which becomes negatively charged and then picks up 2H+ from the surrounding medium to form H2O. This is the only point in aerobic cellular respiration where O2 is consumed.
Note that FADH2, derived from the citric acid cycle, is another source of electrons. However, FADH2 adds its electrons to the electron transport chain at a lower energy level than does NADH+H+. Because of this, the electron transport chain produces about one-third less energy for ATP generation when FADH2 donates electrons as compared with NADH+H+.
The various electron transfers in the electron transport chain generate 32 to 34 ATP molecules from each molecule of glucose that is oxidized: 28 or 30 from the 10 molecules of NADH+H+ and 2 from each of the 2 molecules of FADH2 (4 total). Thus, during aerobic respiration, 36 or 38 ATPs can be generated from one molecule of glucose. Note that two of those ATPs come from substrate-level phosphorylation in glycolysis and two come from substrate-level phosphorylation in the citric acid cycle.
The overall reaction for aerobic respiration is:
C6H12O6 + 6O2 + 36 or 38 ADPs + 36 or 38 Pi
6CO2 + 6H2O + 36 or 38 ATPs
So, where is the truth:?:
Anyway, this spech is uselessly too long and even doesn't answer the question (except of the last paragraph)
Cis or trans? That's what matters.
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