Final answer:
The first use of glucose in the mitochondria is indirect; glucose undergoes glycolysis in the cytoplasm to become pyruvate, which then enters the mitochondria for the Krebs cycle.
Step-by-step explanation:
First Use of Glucose in the Mitochondria
The first use of glucose in the mitochondria during cellular respiration is not actually its direct entry into the mitochondria but rather through a preparatory process that occurs in the cytoplasm, known as glycolysis. Glycolysis converts glucose into pyruvate, producing a small amount of ATP and NADH in the process. After glycolysis, pyruvate then enters the mitochondria where it is further processed in the Krebs cycle, also called the citric acid cycle. In this cycle, pyruvate is converted into acetyl-CoA, which is then fully oxidized to carbon dioxide with the production of more NADH, FADHâ‚‚, and ATP.
This process begins outside the mitochondria and is crucial in the preparatory phase of glucose breakdown. Substances like GLUT proteins and secondary active transport are involved in moving glucose into cells which can be transformed via glycolysis in the cytoplasm, resulting in substances that will be used inside the mitochondria for further energy retrieval.