In the link reaction, pyruvate is turned into a two-carbon acetyl group. This acetyl group is then passed to coenzyme A, forming acetyl coenzyme A (acetyl‑CoA). State the terms used for the two chemical changes that happen in the link reaction as pyruvate is converted into an acetyl group.
In the Krebs cycle, acetyl‑CoA joins with oxaloacetate to make citrate. Citrate synthase catalyses this step. Acetyl‑CoA has a similar shape to succinyl‑CoA, which is one of the compounds formed later in the Krebs cycle. An experiment was carried out to investigate how increasing the concentration of acetyl‑CoA affected citrate synthase activity. The experiment was then repeated with a solution of succinyl‑CoA added. Fig. 8.1 shows the results. Using Fig. 8.1, explain how succinyl‑CoA could regulate the Krebs cycle.
The coenzyme NAD has an important function in respiration. Describe the role of NAD in the stages of aerobic respiration that take place in a mitochondrion.