Question

4. Trace the fate of hydrogens removed from glucose during glycolysis when oxygen is present in muscle cells; compare this to the fate of hydrogens removed from glucose when the amount of available oxygen is insufficient to support aerobic respiration. 5. Why is each of the following essential to chemiosmotic ATP synthesis? (a) electron transport chain (b) proton gradient (c) ATP synthase complex? 6. Sum up how much energy (as ATP) is made available to the cell from a single glucose molecule by the operation of glycolysis, the formation of acetyl coA, the citric acid cycle, and the electron transport system.

Answer 1

ans 1. The end result of glycolysis and the dehydrogenation of glucose is:

-the production of ATP from ADP-ATP provides an energy source for many cellular functions.

-the production of NADH (NADH + H+ provides reducing power for other metabolic pathways or further ATP synthesis.). the production of free hydrogen atoms which are probably used up in further ATP synthesis. in the presence of oxygen product of glucose ie. pyruvate enter in to mitochondria and allow citric acid cycle to form more and more reducing power. these reducing power is used in electron transport chain system to generate maximum ATP with the help of oxidative phosphorylation process.

-the production of puruvate. (Pyruvate is used in the citric acid cycle in aerobic respiration to produce more ATP, or is converted to other small carbon molecules in anaerobic respiration.)

-the production of water (sweat)

in the absence of oxygen, in muscles pyruvate enter in to fermentation process. reducing power obtained from glycolysis is used in this process to form lactic acid. no TCA cyxle, no ETS and no oxidative phosphorylation process in anarobic respiration. lesser amount of ATP formed.

ans 2. each of the following is essential for chemiosmotic synthesis:-

electron transport chain system - in ETC complete breakdown of pyruvate takes place. the ultimate product obtained from pyruvate is ATP, NADH + H+, FADH2 and CO2. these reducing power enter in to ETC system and form more or more ATP. TCA is much more important for chemiosmotic synthesis because it gives maximum no. of reducing power to generate maximum no. of ATP.

proton gradient - Often, the use of a proton gradient is referred to as the chemiosmotic mechanism that drives ATP synthesis since it relies on a higher concentration of protons to generate “proton motive force”. The amount of ATP created is directly proportional to the number of protons that are pumped across the inner mitochondrial membrane.

ATP synthase complex - The formation of ATP from ADP and Pi is energetically unfavorable and would normally proceed in the reverse direction. In order to drive this reaction forward, ATP synthase couples ATP synthesis during cellular respiration to an electrochemical gradient created by the difference in proton (H ) concentration across the mitochondrial plasma membrane in eukaryotes or the plasma membrane in bacteria.

ans 3. total 38.

in glycolysis 2 ATP, 2 NADH + H+

acetyl formation 2 NADH + H+

citric acid cycle 2 ATP, 2 FADH2, 6 NADH + H+