Glycolysis

• Why do organisms need energy?

  • Active transport
  • Maintaining body temp
  • Metabolism- especially anabolic reactions
  • Movement within and of organism itself
• Is glycolysis an aerobic or anaerobic process?

  Anaerobic- doesn’t require oxygen
• What does glycolysis produce?

  • Two 3C pyruvate molecules
  • ATP
  • Reduced NAD
• In terms of stages, what is glycolysis considered as in respiration?

  First stage of cellular respiration
• Where do reactions in bacteria take place?

  • On cell membranes
  • As they do not have mitochondria
• What happens to the phosphate molecules produced at the end of glycolysis?

  • Used to form four ATP molecules
  • Means net yield of ATP is two, as 2 ATP molecules used at start, but four ATP molecules produced at end
• Why is glycolysis described as a substrate level phosphorylation?

  • ATP is formed without the involvement of an electron transport chain
  • ATP formed by the transfer of a phosphate group from a phosphorylated intermediate (in this case triose bisphosphate) to ADP
• How does NAD act as a coenzyme in glycolysis?

  • NAD accepts a hydrogen atom and is reduced
  • Supplies hydrogen to enzyme in later stage of respiration
• What is reduced NAD used for? (2)

  In a later stage to synthesise more ATP for respiration, supplies hydrogen to enzyme involved in later stage of respiration
• describe what is meant by phosphorylation

  • Addition of phosphate molecules from ATP
  • To glucose molecule, forming hexose bisphosphate
  • Catalysed by enzymes
• Describe what is meant by dehydrogenation

  • Removal of hydrogen atoms from triose bisohosphate molecules
  • To form pyruvate and reduced NAD
  • Catalysed by enzymes
• Outline the importance of dehydrogenation and phosphorylation in glycolysis

  • DEHYDROGENATION- hydrogen removed in the breakdown of glucose, hydrogen required at a later stage
  • PHOSPHORYLATION- addition of phosphate groups destabilises glucose, leads to breakdown of glucose and synthesis of ATP
• what is respiration?

  process by which organic molecules like glucose are broken down into simpler inorganic molecules, and the energy stores within the bonds of these organic molecules is used to form ATP
• respiration is an exothermic reaction. More energy is needed when breaking the bonds of oxygen and glucose than released to make the bonds between carbon dioxide and water. What happens to this excess energy released?

  used to make ATP
• state the order of the stages involved in cellular respiration

  1. glycolysis
  2. anaerobic (lactate/alcoholic fermentation) or aerobic respiration (link reaction)
  3. krebs cycle
  4. electron transport chain (oxidative phosphorylation)
  5. oxygen as the final electron acceptor to form water

  
• Describe the stages of glycolysis

  1. Phosphorylation- two phosphate molecules from two ATP molecules bind to 6C glucose Forms hexose bisphosphate
  2. Lysis- phosphorylation destabilises the 6C glucose; it splits into two triose (3C) phosphate molecules
  3. Phosphorylation again- another phosphate group added to each triose phosphate forming two triose bisphosphates, these phosphate groups come from free Pi in the cytoplasm
  4. Dehydrogenation- of triose bisphosphate molecules (aka oxidation). The two removed hydrogens reduce NAD coenzymes and form 2 molecules of reduced NAD
  5. 4 ADP molecules get phosphorylated to ATP molecules using the phosphates from the triose bisphosphate molecules. The resulting molecules are 2 pyruvate molecules

  
• true or false? glycolysis takes place in the mitochondria

  FALSE- takes place in the cytoplasm of the cell