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| ^Cellular Metabolism | |
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| ^Cellular Respiration | |
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| >Respiration Overview | |
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| >Food Breakdown | |
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| *Glycolysis | |
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| >Aerobic Respiration | |
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| >Fermentation |
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Stage 2: Glycolysis
Before glucose can be converted into ATP, it has be broken down into two pyruvate molecules (the ionized form of pyruvic acid). This process is known as glycolysis. Glycolysis takes place in the cytoplasm and can occur without the presence of oxygen and is the primary energy source for most organisms. This process consumes two ATP molecules, and produces four ATP molecules and two NADH2+ molecules. Glycolysis is summarized below:
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1. Glucose 6-phosphate is formed when the 6th carbon on the glucose molecule is phosphorylated by an ATP molecule. 2. Glucose 6-phosphate is converted into a 5-carbon ring isomer, fructose 6-phosphate. 3. Fructose 6-phosphate is phosphorylated by another ATP to form fructose 1, 6-diphosphate. 4. Fructose 1, 6-diphosphate is processed by an enzyme into two glyceraldehyde 3-phosphate molecules. 5. Two molecules of glyceraldehyde 3-phosphate are oxidized, losing hydrogen atoms and gaining phosphate groups to form 1, 3-diphosphoglycerate. Two molecules of NAD+ are converted into NADH2+ in the process. 6. Two 1,3-diphosphoglycerate molecules phosphorylate ADP (adenine diphosphate) to yield two molecules of 3-phosphoglycerate and two ATPs are produced. 7. The phosphate groups on 3-phosphoglycerate move to the 2nd carbon, forming 2-phosphoglycerate. 8. The two 2-phosphoglycerate molecules are dehydrated and forms two high-energy phosphoenolpyruvate molecules. 9. The two phospoenolpyruvate phosphorylates two ADPs and produces two more ATPs and two molecules of pyruvate.
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After the glucose molecule has been converted two pyruvate, it is then sent to the Kreb Cycle to be converted into more usable forms of energy.
Go on to Stage 3: Aerobic Respiration