15. What is glycolysis? Which metabolic pathways use glycolysis? Describe what h
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15. What is glycolysis? Which metabolic pathways use glycolysis? Describe what happens to a glucose molecule during glycolysis. What are the reactants an products of this process? What is the overall equation for glycolysis? 16. What is pyruvate oxidation? Describe what happens to a pyruvic acid molecule during pyruvate oxidation. What are the reactants and products of this process? What is the overall equation for pyruvate oxidation? 17. What is the Krebs cycle? Describe what happens to an acetyl CoA molecule during Krebs cycle. What are the reactants and products of this process? What is the overall equation for the Krebs cycle? 18. What is the Electron Transport Chain? Describe what happens to the electron carrier molecules, electrons, H, and O2 during Electron Transport Chain. What are the reactants and products of this process? What is the overall equation for the Electron Transport Chain? 19. Why do heterotrophs breathe O,? Why do they have to consume (from eating) molecules like glucose?Explanation / Answer
15. Glycolysis occurs In the cytoplasm of a cell, the glucose is degraded by the glycolysis pathway. One glucose molecule (6 Carbon compound) enters into glycolysis produces two molecules of pyruvate (3 Carbon compound). During the degradation of glucose molecule produces two molecules of NADH and four ATPs but two ATPs are utilized for glycolysis process so the net gain is two ATPs at the end of glycolysis. Finally, only two ATP molecules are produced from degradation of one molecule of glucose by glycolysis pathway.
Glucose+ 2ADP+2NAD+ => 2 Pyruvate+ 2ATP + 2 NADH
Steps:
Glucose -> Glucose 6-phosphate -> Fructose 6-phosphate -> Fructose 1,6-bisphosphate -> Dihydroxyacetone phosphate & Glyceraldehyde 3-phosphate -> Glyceraldehyde 3-phosphate -> 1,3-Bisphosphoglycerate -> 3-Phosphoglycerate -> 2-Phosphoglycerate -> Phosphoenolpyruvate -> 2 Pyruvate.
Reactants = Glucose, ADP+ NAD+
Products = Pyruvate, 2ATP, NADH
16. Pyruvate oxidation occurs in Mitochondria of the cell. The two private molecules produced in glycolysis do not directly enter into the Kreb’s cycle for further degradation. First, they are converted to acetyl coenzyme A by the enzyme called pyruvate dehydrogenase which is degraded by Krebs cycle enzymes. During this conversion, two NADH molecules are generated from two pyruvate molecules and two CO2.
Steps:
2 pyruvate => 2 acetyl-CoA
2Pyruvate+ 2NAD+ 2 Acyl coenzyme A => 2 acetyl coenzyme A+ 2CO2+ 2 NADH2
Reactants = Pyruvate+ NAD+ Acyl coenzyme A
Products = acetyl coenzyme A, CO2, NADH2
17. Krebs cycle: it is also called citric acid cycle or tricarboxylic acid cycle, occurs in Mitochondria. The acetyl coenzyme A combine with one oxaloacetate molecule produces citrate. The citrate molecule degraded and oxaloacetate molecule is regenerated. During Krebs cycle, two GTP, two FADH2, six NADH2 and 2 Co2 are produced from two molecules of private.
Steps:
Oxaloacetate + Acetyl CoA -> Citrate -> Isocitrate -> Oxalosuccinate -> -Ketoglutarate -> Succinyl-CoA -> Succinate Fumarate -> L-Malate -> Oxaloacetate
2Oxaloacetate +2 Acetyl CoA+2GDP+2FAD+ + 6NAD+ => 2Oxaloacetate+ 2GTP+2 FADH2 + 6NADH2
Reactants = Oxaloacetate, Acetyl CoA, GDP, FAD+ 6NAD+
Products = 2Oxaloacetate, 2GTP, FADH2, NADH2
18. Electron transport chain is located in the inner mitochondrial membrane. The reducing equivalents (NADH2 and FADH2) generated in glycolysis, the formation of acetyl coenzyme A, Kreb’s cycle are oxidized by the donating electrons to the oxygen by the four electron carrier complexes of electron transport chain. The four protein complexes which carry electrons from the NADH2 and FADH2 to terminal oxygen and produces the NAD+, ATP, H2O. Generation of ATP by the oxidation of NADH2 and FADH2 by electron transport chain is called oxidative phosphorylation. During the oxidation NADH2 and FADH2 by the four complexes of ETC the H+ ions move from matrix to intermembrane space of mitochondria and generate the proton gradient across the inner mitochondrial membrane which is used by the ATP synthase complex of mitochondria to produce ATP. During the aerobic respiration total, 36 ATPs are produced.
NADH2+FADH2+ O2 => NAD++FAD++H20+32ATP
Reactants = NADH2, FADH2, O2
Products = NAD+, FAD+, H20, 32ATP
19. A series of metabolic steps used to extract the energy from the organic molecules like glucose is called cellular respiration. If the cellular respiration occurs in the presence of oxygen, it is called aerobic cellular respiration. The oxygen which is taken by the heterotrophs during the respiration utilized for the oxidation of NADH2 and FADH2. When we consume molecules like glucose it is utilized to produce the energy. The glucose degraded by the glycolysis, Krebs cycle, ETC and produces 36 ATP molecules which main energy currency for the cell.
C6H12O6 + 6O2 6CO2 +6H2O + 36 ATP
It is the equation for glucose oxidation in aerobic respiration.
Energy gain: total 36 ATPs
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