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Na+ is a critical ion that influences the action potential in nerve cells. During the transmission of an impulse, the cell membrane is open so ions can flow through it, i.e., positively charged ions such as sodium ions (Na +) move within the cell, while negatively charged ions move outside the cell. This process produces a change in the action potential by rapidly increasing the positive charge in the nerve fiber, being thus the impulse propagated when this charge reaches +40 mv. In consequence, the effects of Na + on the single-channel current can be analyzed by removing positive ions and determining the change in the reversal potential of this channel.

7 0

4 years ago

The citric acid is a stage of catabolism that oxidizes acetate into carbon dioxide and generates energy. There are eight enzymes

3241004551 [841]

Answer:

1.(a ) alpha-ketoglutarate dehydrogenase

(c) malate dehydrogenase

(d) isocitrate dehydrogenase

2. b. isocitrate dehydrogenase d. alpha-ketoglutarate dehydrogenase

3. b. citrate synthase (c) succinyl-CoA synthesase

4. b. alpha-ketoglutarate dehydrogenase c. citrate synthase d. malate dehydrogenase

5. a. aconitase

Explanation:

The citric acid cycle is responsible for the oxidation of acetyl-CoA produced from pyruvate from glycolysis. The citric acid cycle has eight steps requiring nine enzymatic reactions involving eight enzymes.

The enzymes in the citric acid cycle are: citrate synthase , aconitase, isocitrate dehydrogenase, alpha-ketoglutarate dehydrogenase , succinyl-CoA synthesase, succinate dehydrogenase , fumarase , and malate dehydrogenase .

1. The dehydrogenation reactions of isocitrate dehydrogenase, alpha-ketoglutarate dehydrogenase , and malate dehydrogenase produces NADH from isocitrate, alpha-ketoglutarate and malate respectively.

2. Oxidative decorboxylation (removal of carbon as CO₂) also occurs in the reactions of isocitrate dehydrogenase and alpha-ketoglutarate dehydrogenase to produce alpha-ketoglutarate and succinyl-CoA respectively.

3. Coenzyme-A (CoA-SH) is produced in the reactions of citrate synthase and succinyl-CoA sythetase to produce citrate and succinate respectively.

4. The enzymes alpha-ketoglutarate dehydrogenase has alpha-ketoglutarate as substrate , whereas citrate synthase and malate dehydrogenase has oxaloacetate as substrate. These substrates are alpha-keto acids.

5. Aconitase catalyzes the conversion of citrate to isocitrate by first a dehydration and then a hydration reaction.

6 0

4 years ago