If oxygen is not available at the mitochondria the pyruvate and NADH produced in glycolysis cannot move into the mitochondria to be further processed into the additional 34 units of ATP. Can you see how this might account for a low level of ATP and elevated levels of pyruvate in the cell? (If you cannot see this you may want to start back at page 9 and review the information. Don't forget there are many mitochondria in the cell and many ongoing glycolysis operations producing pyruvate.)
Also, in an anaerobic environment the mitochondria is not able to produce the other by-products of these processes, namely carbon dioxide (CO2) and water (H2O). We will speculate on possible effects of this later in this presentation.
Keep in mind that this is not an absolute situation. Depending on the type of cell and its energy needs, there are tens, hundreds, or thousands of mitochondria at work in the cell. All working to produce ATP to meet the energy needs of the cell.
For example, lets say that a particular cell contains 100 mitochondria ready to process incoming pyruvate into ATP. Lets also assume that the current cellular activity needs all the ATP that can be produced. What if only 95% of the total oxygen requirements of the mitochondria are being delivered to the cell? That means that 95 of the 100 total mitochondria in this cell will receive the oxygen needed to produce ATP inside the mitochondria.
The balance of the ATP required by the cell would be manufactured by glycolysis. Remember that glycolysis does not require oxygen. However, glycolysis will also produce a buildup of pyruvate inside the cell which the cell must further process in the mitochondria. But, this requires oxygen. Or, it must convert the pyruvate to lactic acid and remove it from the cell.
Speculation:
If ATP production bottlenecks develop at the mitochondria this
may then impact the processes that precede it; Affecting
glycolysis and eventually affecting the amount of glucose that the
cell can process. Possibly creating elevated glucose levels in the
blood. Fatty acids are also processed into ATP in muscle cells.
it may be possible that if these processes are backing up there could
be a rise in triglycerides in the blood too.
There will be times that the cell will not have sufficient oxygen to generate ATP through the aerobic pathways in the mitochondria, the Kreb cycle and Electron Transport Chain. During these periods the cell is able to produce ATP anaerobically via glycolysis. We will discuss this on the next page.
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