What is pyruvate primarily characterized as in cellular respiration?

In cellular respiration, pyruvate is primarily characterized as being oxidized before joining the Krebs cycle (also known as the citric acid cycle). After glycolysis, which takes place in the cytoplasm, glucose is broken down into two molecules of pyruvate. These pyruvate molecules then enter the mitochondria for further processing.

Before entering the Krebs cycle, pyruvate undergoes decarboxylation, where it is oxidized to form acetyl-CoA. This step is crucial because acetyl-CoA serves as the substrate that feeds into the Krebs cycle, allowing for the continuation of energy production. During this process, carbon dioxide is released, and NAD+ is reduced to NADH, which plays a key role in the electron transport chain later in cellular respiration.

The other choices do not accurately describe the primary role of pyruvate in cellular respiration. While pyruvate can be converted to fatty acids in certain metabolic pathways, that function is not its primary characterization in the context of cellular respiration. Reducing pyruvate to lactate occurs under anaerobic conditions, particularly in muscle cells, but it is not the main pathway in aerobic respiration. Additionally, pyruvate itself is not phosphorylated for glycolysis; rather,