Gen Bio 1 L10: Glycolysis

• Glycolysis: it is the first step in aerobic respiration.
• Glycolysis: it is a metabolic pathway that occurs in the cytoplasm.
• Glycolysis: it involves breakdown of glucose into two molecules oof pyruvate.
• Glycolysis: anaerobic respiration, does not require oxygen.
• Glycolysis: an essential step in aerobic cell respiration because it provides the starting material for the subsequent steps that occur in the mitochondria.
• 2 MAIN PHASES OF GLYCOLYSIS: 1) The Energy Investment Phase, 2) The Energy Payoff Phase
• Energy Investment Phase: steps 1-3
• Step 1: Glucose is Phosphorylated by the enzyme Hexokinase (HK) using one molecule of ATP.
• Step 1: It converts glucose into glucose-6-phosphate
• Step 2: Glucose-6-phosphate is converted to fructose-6-phosphate by phosphoglucose isomerase (PGI).
• Step 3. Phosphoglucose isomerase (PGI) is phosphorylated by the enzyme phosphofructokinase-1 (PFK) using another molecule of ATP, producing fructose-1,6-biphosphate.
• Energy Payoff: steps 4-10
• Step 4. Fructose-1,6-biphosphate is split into 3-Carbon molecules: dihydroxyacetone phosphate (DHAP), producing Glyceraldehyde 3-phosphate (G3P).
• Step 5. Dihydroxyacetone phosphate (DHAP) is oxidized by triose phosphate (TP) isomerate to produce glyceraldehyde 3-phosphate (G3P)
• Step 6. G3P is oxidized and phosphorylated by the enzyme glyceraldehyde dehydrogenase (GAPDH) producing NADH and 1,3 bisphosphoglycerate.
• Step 7. 1,3 bisphosphoglycerate donates a phosphate group to ADP forming ATP and 3-phosphoglycerate
• Step 8. 3-Phosphoglycerate is converted to 2-phosphoglycerate by the enzyme phosphoglycerate mutase (PGM)
• Step 9. 2-Phosphoglycerate is converted to phosphoenolpyruvic acid (PEP) by the enzyme enolase (ENO)
• Step 10. PEP is reduced to pyruvate by the enzyme pyruvate kinase (PK) with the production of ATP from ADP
• Step 10. Phosphoenolpyruvate (PEP) donates the phosphate group to ADP forming ATP and pyruvate (PK - pyruvate kinase)
• At the end of Glycolysis, one molecule of glucose is converted into two molecules of pyruvate and a net gain of two ATP and two NADH.