Final answer:
Pyruvate can be converted into various molecules such as lactate, acetyl-CoA, and oxaloacetate, but not directly into glucose. Glucose is synthesized from pyruvate, among other substrates, during gluconeogenesis.
Step-by-step explanation:
Pyruvate is a critical metabolic hub with various potential fates within the cell. If oxygen is present, allowing for aerobic respiration, pyruvate is transported into the mitochondria and converted into acetyl-CoA through an oxidative decarboxylation reaction, priming it for the citric acid cycle. During intense exercise or oxygen-limiting conditions, pyruvate can be converted into lactate via lactate dehydrogenase. Additionally, pyruvate can be aminated to form alanine or be used to produce oxaloacetate, playing a role in gluconeogenesis.
When glucose is scarce, the body can synthesize it through gluconeogenesis from non-carbohydrate sources, including lactate, alanine, and pyruvate. However, glucose itself cannot be made from pyruvate in this process, as it is actually a substrate used in the production of glucose through gluconeogenesis.
Therefore, the correct answer to the question is D. Glucose, which is not directly made from pyruvate but rather is synthesized from non-carbohydrate sources, including pyruvate in a more roundabout way.