During which phase of cellular respiration is carbon dioxide released? (1 point)
• Krebs cycle
• glycolysis
• digestion
electron transport chain
• Krebs cycle
Carbon dioxide is released during the Krebs cycle phase of cellular respiration.
During the Krebs cycle phase of cellular respiration, carbon dioxide is released. The Krebs cycle, also known as the citric acid cycle or the tricarboxylic acid cycle, is a series of chemical reactions that occurs in the mitochondria of cells. It is the second stage of cellular respiration, following glycolysis.
To understand why carbon dioxide is released during the Krebs cycle, it's important to know the overall process of cellular respiration. Cellular respiration is the process through which cells generate energy by breaking down glucose molecules and converting them into ATP (adenosine triphosphate), the primary energy currency of cells. The process consists of three main stages: glycolysis, the Krebs cycle, and the electron transport chain.
Glycolysis occurs in the cytoplasm and serves as the initial step of cellular respiration. It breaks down a molecule of glucose into two molecules of pyruvate, producing a small amount of ATP and NADH (nicotinamide adenine dinucleotide, a coenzyme involved in energy production). However, carbon dioxide is not directly released during glycolysis.
Next, the Krebs cycle takes place in the mitochondria matrix. The pyruvate molecules derived from glycolysis are converted into a molecule called Acetyl-CoA and enter the Krebs cycle. During this cycle, Acetyl-CoA reacts with a four-carbon molecule, called oxaloacetate, to produce a six-carbon compound called citric acid. Through a series of enzymatic reactions, citric acid is further broken down, releasing carbon dioxide as a byproduct. This is where carbon dioxide is released during cellular respiration.
Finally, the electron transport chain, which occurs on the inner membrane of the mitochondria, receives electron carriers (NADH and FADH2) produced during previous stages and generates the majority of ATP. However, carbon dioxide is not directly involved in the electron transport chain.
In summary, carbon dioxide is released during the Krebs cycle phase of cellular respiration. To determine which phase of cellular respiration releases carbon dioxide among the given options, the answer would be the Krebs cycle.