Final answer:
The pathways of glucose catabolism include glycolysis, where glucose is converted to pyruvate, and the oxidative decarboxylation of pyruvate to acetyl-CoA, which then enters the citric acid cycle. Acetyl-CoA does not convert back to pyruvate, but is involved in the citric acid cycle and fatty acid synthesis.
Step-by-step explanation:
The student is asking about the different pathways of glucose catabolism, specifically about matching reactants and products with specific stages in the biochemical pathways. Let's address each match:
- a) Glucose → Pyruvate: This transformation occurs during glycolysis, where a molecule of glucose is broken down into two molecules of pyruvate.
- b) Pyruvate → Acetyl-CoA: This transformation is part of the oxidative decarboxylation of pyruvate, which takes place in the mitochondria when oxygen is present, before entering the citric acid cycle.
- c) Glucose → Acetyl-CoA: This is a two-step process. First, glucose is converted to pyruvate via glycolysis, and then pyruvate is converted to acetyl-CoA.
- d) Acetyl-CoA → Pyruvate: This conversion does not typically occur as acetyl-CoA does not convert back to pyruvate; instead, it enters the citric acid cycle or is utilized in fatty acid synthesis.
In summary, the breakdown of glucose begins with glycolysis, resulting in the formation of pyruvate. Under aerobic conditions, pyruvate is then converted into acetyl-CoA, which enters the citric acid cycle. During this cycle, NADH and FADH2 are produced, which enter the electron transport chain to generate ATP through chemiosmosis. Additionally, the regulation of cellular respiration is essential for efficient metabolic control, responding to levels of nucleosides and other pathway intermediates to regulate enzyme activity.