In the Krebs cycle, how is citric acid formed?(1 point)
Responses
Pyruvic acid molecules are broken down by an acetyl group.
Pyruvic acid molecules are broken down by an acetyl group.
Enzymes combine hydrogen ions, oxygen, and electrons.
Enzymes combine hydrogen ions, oxygen, and electrons.
Acetyl-CoA joins with a large molecule called oxaloacetic acid.
Acetyl-CoA joins with a large molecule called oxaloacetic acid.
Carbon dioxide bonds with a chain of coenzyme A.
Pyruvic acid molecules are broken down by an acetyl group.
In the Krebs cycle, citric acid is formed when Acetyl-CoA joins with a large molecule called oxaloacetic acid.
The correct answer is: Acetyl-CoA joins with a large molecule called oxaloacetic acid.
In the Krebs cycle, also known as the citric acid cycle or the tricarboxylic acid cycle, citric acid is formed through a series of biochemical reactions. Here's a step-by-step explanation:
1. First, an acetyl group from acetyl-CoA combines with a molecule called oxaloacetic acid (a 4-carbon compound) to form a 6-carbon compound called citric acid. This reaction is catalyzed by an enzyme called citrate synthase.
2. Next, the citric acid goes through a series of transformations, where it is metabolized and rearranged. During these reactions, carbon atoms from the citric acid are released as carbon dioxide (CO2).
3. At several steps in the cycle, electron carriers such as NADH and FADH2 are produced, which will later participate in the electron transport chain to generate ATP (cellular energy).
4. As the cycle progresses, the original oxaloacetic acid molecule is regenerated, ready to react with another acetyl-CoA and go through the cycle again.
To summarize, citric acid is formed in the Krebs cycle when acetyl-CoA joins with oxaloacetic acid. The cycle's purpose is to produce energy-rich molecules (ATP) and electron carriers for further energy production.