Question

1) Draw the whole cellular respiration cycle: Glycolysis, Bridge Step, and Krebs cycle (don't have to draw the molecules, just the names and all of the intermediates).

Answer 1

A series of metabolic steps used to extract the energy from the organic molecules like glucose is called cellular respiration

Glycolysis: 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. By the degradation of three glucose molecules produces net 6 ATP molecules (12 ATPs are produced but 6 are used during glycolysis so net ATPs are 6 only).

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 -> Pyruvate

Formation of acetyl coenzyme A: 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 CO_2.

pyruvate          ->        acetyl-CoA

Krebs cycle: also called citric acid cycle or tricarboxylic acid cycle. The acetyl coenzyme A combine with one oxaloacetate molecule produces citrate. The citrate molecule degraded and oxaloacetate molecule is regenerated. During Krebs cycle, two carbons are released as a CO₂ and one GTP, one FADH₂, three NADH₂ are produced from one molecule of private.

Oxaloacetate + Acetyl CoA -> Citrate -> Isocitrate -> Oxalosuccinate -> α-Ketoglutarate -> Succinyl-CoA -> Succinate   Fumarate -> L-Malate -> Oxaloacetate