Cell Respiration Brandon Schroeder, Matt Gobel, & Julia Douglas
Oxidation: is the loss of electrons
generally by gaining oxygen or losing hydrogen.
Reduction: is gaining electrons
generally by gaining hydrogen or losing oxygen
Mitochondrion have a large inner matrix, allowing for the Krebs cycle to occur.
The inner membrane contains many electron transport chains of proton pumps and ATP synthase enzymes, allowing for the greatest yield of ATP to be produced.
The membranes are also structured to prevent the protons from diffusing though the membrane, forcing them to enter the matrix only through ATP synthase molecules.
Cell Respiration : the controlled release of energy from organic compounds in cells to form ATP
Glycolysis occurs during cell respiration
Glucose in cytoplasm is broken down into pyruvate
Nets a small yield of ATP
Anaerobic Respiration: after glycolysis pyruvate is converted in cytoplasm into one of the following:
Commonly produced in humans
Ethanol and Carbon Dioxide
Commonly produced in yeast
Nets no further yield of ATP
Aerobic Respiration: after glycolysis pyruvate is broken down in mitochondrion into (both):
Nets large yield of ATP
strictly refers to the steps of Krebs cycle, electron transport chain, and oxidative phosphorylation.
Glycolysis is a ten-step process:
Glucose is phosphorylated into glucose-6-phosphate by hexokinase, turning one ATP into ADP(Adenosine diphosphate) in the process.
2. Glucose-6-phosphate is transformed into fructose-6-phosphate by phosphoglucoisomerase.
3. Fructose-6-phosphate is phosphorylated into fructose-1,6-diphosphate by phosphofructokinase, turning one ATP into ADP in the process.
4. Fructose-1,6-diphosphate is lysed by aldolase into dihydroxyacetone phosphate (DHAP) and 3-phosphoglyceraldehyde (PGAl).
5. Isomerase promptly transforms DHAP into a second molecule of PGAl.
6. Two molecules of PGAl are oxidized by 2 molecules of NAD+, creating 2 NADH + H+. The redox reaction provides the energy for triose phosphate dehydrogenase to attach a phosphate group to each PGAl, yielding two molecules of 1,3-diphosphoglycerate (DPG).
7. Two molecules of DPG are used to phosphorylate two molecules of ADP with the help of phosphoglycerokinase (substrate-level phosphorylation), yielding 2 ATP and two molecules of 3-phosphoglycerate.
8. Two molecules of 3-phosphoglycerate have their phosphate group relocated by phosphoglyceromutase, yielding two molecules of 2-phosphoglycerate.
9. Two molecules of 2-phosphoglycerate are transformed by enolase into two molecules of phosphoenolpyruvate (PEP) through the removal of water.
10. Two molecules of PEP are used to phosphorylate two molecules of ADP with the help of pyruvate kinase, yielding 2 ATP and two molecules of pyruvate.
Acetyl CoA gives acetate to combine with oxaloacetate to form citrate Coenzyme A exits the cycle to be recycled for further use.
Citrate is converted to isocitrate, which then loses a CO 2 and is then oxidized and forms α-ketoglutarate (C 5 ), reducing NAD + to NADH + H +
the remaining molecule is attached to Coenzyme A to form succinyl CoA. Succinyl CoA is then used to phosphorylate a GDP to GTP
The GTP then phosphorylates an ADP to ATP
The remaining C 4 compound, succinate, is oxidized reducing FAD to FADH 2 , and with the addition of water, forms malate
Malate is oxidized reducing NAD + to NADH + H + , and forming oxaloacetate
The Krebs cycle in total yields 2 CO 2 , 1 ATP, 3 NADH + H + , and 1 FADH 2 per pyruvate.
The NADH + H + and FADH 2 go on to participate in the electron transport chain.
Electron Transport Chain
Electrons are given to proton pumps that are embedded in the membrane between the matrix and inner membrane/cristae of the mitochondrion.
The pumps are reduced, giving them energy to pump protons into the inner membrane space.
The electrons are transferred along a chain of pumps, continuously losing energy.
Protons diffuse back into the matrix through facilitated diffusion of ATP synthase (channel protein and enzyme).