ATP: Appalachian Trail Physiology or, Adenosine Triphosphate
Once upon a time there was a beautiful organelle named Mitochondria who lived in a thigh muscle cell of an Appalachian Trail hiker. She was in charge of providing energy to the cell when the hiker started walking. She needed the hiker to eat well, drink water, and get good rest at the end of each day.
With each step the hiker took, her good friend Aldolase received glycogen molecules delivered to the cell from the hiker’s liver by insulin from the hiker’s pancreas. Using two Adenosine Triphosphate (ATP) molecules for energy, Aldolase applied hexokinase and other enzymes to split the glycogen molecules into pyruvate, which she gave to Mitochondria.
Mitochondria took the pyruvate and applied to it a process named Krebs. She used water, Oxaloacitate (OAA), and Coenzyme A (CoA) to split the carbon atoms away from the pyruvate molecule. In doing so she produced Acetyl-CoA, NADH, citric acid, Adenosine Diphosphate (ADP), and carbon dioxide. She sent the carbon dioxide to the blood stream for the hiker to exhale. This process also created much heat, which she also sent to the blood.
Using the electrons from the NADH, Mitochondria ran the process a second time to turn the ADP into more ATP. Mitochondria gave this ATP back to Aldolase who in turn used it to disassemble the next glycogen molecule. Additionally, leftover electrons from the NADH process bonded with hydrogen and oxygen in the cell, creating water. Mitochondria also saved this water to use in the next Krebs cycle.
Finally, the resulting NAD molecules went about assisting the cell with conducting physical work such as contracting or relaxing. They also cleaned up waste products generated by all the work done by Mitochondria and Aldolase.
Then the hiker took another step. Wash, rinse, repeat.
One mile down, 2,188.8 to go…
See you on the high ground.
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