What happens during the Krebs Cycle?

What happens during the Krebs Cycle?

• A. Breaks down glucose into lactic acid
• B. Produces carbon dioxide and transfers electrons
• C. Converts pyruvate to glucose
• D. Generates ATP exclusively in the absence of oxygen

Answer: (B)

During the Krebs Cycle, also known as the citric acid cycle or tricarboxylic acid cycle (TCA), the primary functions involve the breakdown of acetyl-CoA to produce carbon dioxide and generate electron carriers. The cycle operates within the mitochondria and plays a critical role in cellular respiration. As acetyl-CoA enters the Krebs Cycle, it combines with a four-carbon molecule to form citrate, which undergoes a series of transformations. Throughout the cycle, two carbon dioxide molecules are released for each acetyl-CoA that enters the cycle. This is significant as it contributes to the expulsion of waste products from the cellular respiration process. Moreover, the cycle generates high-energy electron carriers such as NADH and FADH2, which are crucial for the subsequent electron transport chain, where ATP is ultimately produced. The transfer of electrons to these carriers is a vital step in capturing energy that will later be used to produce ATP. The other options refer to different metabolic pathways or processes. The breakdown of glucose into lactic acid occurs mainly under anaerobic conditions during fermentation, not in the Krebs Cycle. The conversion of pyruvate to glucose refers to gluconeogenesis, a process that is separate and takes place primarily in the liver.

During the Krebs Cycle, also known as the citric acid cycle or tricarboxylic acid cycle (TCA), the primary functions involve the breakdown of acetyl-CoA to produce carbon dioxide and generate electron carriers. The cycle operates within the mitochondria and plays a critical role in cellular respiration.

As acetyl-CoA enters the Krebs Cycle, it combines with a four-carbon molecule to form citrate, which undergoes a series of transformations. Throughout the cycle, two carbon dioxide molecules are released for each acetyl-CoA that enters the cycle. This is significant as it contributes to the expulsion of waste products from the cellular respiration process.

Moreover, the cycle generates high-energy electron carriers such as NADH and FADH2, which are crucial for the subsequent electron transport chain, where ATP is ultimately produced. The transfer of electrons to these carriers is a vital step in capturing energy that will later be used to produce ATP.

The other options refer to different metabolic pathways or processes. The breakdown of glucose into lactic acid occurs mainly under anaerobic conditions during fermentation, not in the Krebs Cycle. The conversion of pyruvate to glucose refers to gluconeogenesis, a process that is separate and takes place primarily in the liver.