Gycolysis

• Aerobic respiration


  Requires oxygen and involves the conversion of glucose into carbon dioxide, water, and energy
• Every cell in the body is constantly producing energy
• Electron exchanges in metabolic pathways use the electron carriers NAD+ and NADH
• Glucose and other biomolecules are the starting material for metabolic processes in our bodies
• The sun releases enormous amounts of energy as a byproduct of nuclear fusion reactions
• Glycolysis


  First pathway of cellular respiration, occurs in the cytoplasm, splits glucose into two pyruvate molecules, anaerobic, yields a net of two ATPs
• Glycolysis - Glucose-6-phosphate isomerization


  Glucose-6-phosphate isomerizes to become fructose-6-phosphate, catalyzed by phosphoglucoisomerase
• Glycolysis is the most evolutionarily ancient metabolic pathway
• Glycolysis is anaerobic, meaning it does not require oxygen
• Plants absorb sunlight, carbon dioxide, and water to make glucose
• Glucose can be converted into carbon dioxide, water, and energy in the presence of oxygen
• Glycolysis - Further steps

  There are 10 steps in glycolysis, catalyzed by 10 enzymes, with an investment of two ATP molecules in the preparatory phase to get four ATPs back over several steps in the payoff phase
• The energy ultimately comes from the sun
• Glycolysis - Hexokinase reaction

  Hexokinase phosphorylates the oxygen on carbon 6 to make glucose 6-phosphate, costs 1 ATP
• Energy is needed for everything


  From running a race to simply breathing
• NAD+


  An electron carrier that can exist as NAD+ or NADH
• Cellular respiration


  The degradation of biomolecules to generate energy that cells can use
• Cellular respiration happens over three major pathways: glycolysis, the citric acid cycle, and oxidative phosphorylation
• Glycolysis occurs in even the simplest cells
• The payoff phase of glycolysis involves the last five steps, converting each GADP molecule into pyruvate, producing two ATP each, for a total of four ATP, resulting in a net energy production of two ATP from one molecule of glucose
• Glycolysis is a 10-step process
• The preparatory phase of glycolysis involves the first five steps, producing two molecules of GADP from one molecule of glucose, costing two ATP
• Glycolysis

  Glucose enters the cell by diffusion, costing 1 ATP for phosphorylation to glucose-6-phosphate

  2. Glucose-6-phosphate isomerizes to fructose-6-phosphate catalyzed by phosphoglucoisomerase

  3. Phosphorylation on carbon 1 hydroxyl to form fructose-1,6-bisphosphate catalyzed by phosphofructokinase 1, costing another ATP

  4. Fructose-1,6-bisphosphate is cleaved into glyceraldehyde-3-phosphate (GADP) and dihydroxyacetone phosphate (DHAP) by fructose bisphosphate aldolase

  5. DHAP is converted to another GADP by triosephosphate isomerase, resulting in two GADP molecules

  6. Oxidation of GADP to 1,3-bisphosphoglycerate using NAD+ and phosphate catalyzed by glyceraldehyde phosphate dehydrogenase

  7. Phosphoglycerate kinase transfers a phosphate group to ADP to form 3-phosphoglycerate, producing one ATP

  8. Phosphoglycerate mutase transfers the phosphate to form 2-phosphoglycerate

  9. Enolase catalyzes a dehydration to produce phosphoenolpyruvate

  10. Pyruvate kinase transfers the remaining phosphate to ADP, generating another ATP and pyruvate
• Glucose in the cytoplasm of the cell is converted into pyruvate through glycolysis, which is then used in the next stage of cellular respiration