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A Summary Of Glycolysis
🎧 Episode Summary:
Welcome to Biochem Bytes, your go-to podcast for mastering core biochemistry topics in minutes. In today’s episode, we’re breaking down glycolysis—the central pathway of glucose metabolism.
Glycolysis Simplified:
Glycolysis is a 10-step metabolic pathway that occurs in the cytoplasm of all cells. It converts one molecule of glucose (a 6-carbon sugar) into two molecules of pyruvate (a 3-carbon compound), generating ATP and NADH in the process.
The pathway is anaerobic, meaning it doesn’t require oxygen, making it crucial for energy production in low-oxygen conditions like muscle contraction during intense exercise.
Key Phases:
Glycolysis can be divided into two major phases:
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Energy Investment Phase:
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Steps 1 to 5
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Two ATP molecules are consumed to phosphorylate glucose and form fructose-1,6-bisphosphate.
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Energy Payoff Phase:
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Steps 6 to 10
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Four ATP molecules and two NADH molecules are produced per glucose.
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Key Enzymes & Regulatory Steps:
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Hexokinase/Glucokinase: Converts glucose to glucose-6-phosphate (Step 1)
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Phosphofructokinase-1 (PFK-1): The major rate-limiting enzyme (Step 3)
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Pyruvate Kinase: Catalyzes the final step forming pyruvate and ATP
Net Yield (per glucose molecule):
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2 ATP (4 produced – 2 used)
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2 NADH
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2 Pyruvate
Clinical Tie-In:
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Pyruvate kinase deficiency can lead to hemolytic anemia due to impaired ATP production in red blood cells.
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In cancer cells, glycolysis is upregulated even in the presence of oxygen—a phenomenon known as the Warburg effect.
Takeaway Message:
Glycolysis is fundamental—not just for energy but for connecting to other pathways like the TCA cycle and fermentation. Understanding its regulation is crucial for both normal physiology and pathology.
