cellular respirations u1 AoS1

• Photosynthesis


  Biochemical pathway involving many steps controlled by enzymes and assisted by coenzymes
• Cellular respiration


  Biochemical pathway involving many steps controlled by enzymes and assisted by coenzymes
• Enzymes


  • Control biochemical pathways
• Coenzymes


  • Assist biochemical pathways
• Autotrophs


  Organisms that can create organic molecules like glucose from inorganic molecules
• Heterotrophs


  Organisms that cannot create their own organic molecules and rely on autotrophs
• Both autotrophs and heterotrophs undergo cellular respiration
• Cellular respiration involves the breakdown of glucose to create ATP as a cellular fuel
• Sacrificial Gummy Bears


  1. Sucrose (glucose and fructose) broken down in an exothermic, catabolic reaction

  2. Presence of light/heat energy indicates bonds were broken and potential chemical energy was released
• Cellular respiration


  Catabolic reaction where glucose is broken apart to release chemical energy, which is used to drive ATP production
• Humans are heterotrophs and unable to synthesise glucose, so must obtain it from autotrophs or other heterotrophs
• Potassium chlorate decomposition


  2KClO3(s) 2KCl(s) + 3O2(g)
• Gummy bear combustion


  C6H12O6 (s) + 6O2 (g) 6CO2(g) + 6H2O (g)
• Aerobic cellular respiration: C6H12O6 + 6O2 6CO2 + 6H2O + 30-32 ATP
• Cellular respiration purpose


  To 'recharge' cell batteries by creating ATP as an energy source for cell metabolic processes
• ATP


  Immediate source of energy for cells, energy is released when the terminal phosphate group is removed
• Cellular respiration


  Catabolic, exergonic reaction where glucose is broken down into smaller molecules
• Cellular respiration


  Complex biochemical pathway regulated by enzymes, can take aerobic or anaerobic pathways
• Mitochondria


  • Prokaryotic in origin, evolved from ancient purple bacteria
  • Have inner and outer membranes, circular DNA, ribosomes, and plasmids
• Mitochondria are membrane-bound organelles, so will not be found in prokaryotic cells
• Overview of cellular respiration

  1. Glycolysis

  2. Krebs Cycle

  3. Electron Transport Chain
• Common coenzymes


  • ATP
  • NADH
  • NADPH
  • FADH
• Coenzymes


  Non-protein compounds that bind to the active site of enzymes to catalyse specific reactions
• Stage 1: Glycolysis


  Breaks down glucose into pyruvate, occurs in the cytosol, generates 2 ATP, 2 NADH
• Stage 2: Krebs Cycle

  Pyruvate travels into the mitochondrial matrix and is cycled, oxygen must be present, produces CO2, NADH and FADH
• Stage 3: Electron Transport Chain


  Occurs on the cristae of the mitochondria, NADH and FADH carry H+ and electrons, proton gradient formed to drive ATP synthesis, oxygen is the final electron acceptor
• AD*


  Carry H+ and electrons over to the Electron Transport Chain (NADH and FADH)
• Stage 3: Electron transport chain

  1. Occurs on the cristae (folded inner membrane)

  2. Hydrogen is carried over to the cristae (NADH + FADH) and electrons shuttled across the membrane, creating a proton gradient (i.e. the H protons move out)

  3. Enzymes on cristae called cytochromes act as electron carriers

  4. Electrons passed from one carrier to the next, losing energy as they go

  5. Proton gradient (H+) formed -> this allows production of ATP as protons (H+) diffuse through ATP Synthase – kinetic energy transformed and used to phosphorylate ADP

  6. Oxygen is the final acceptor –it accepts spent electrons and combines with hydrogen to produce water
• Produces 2 ATP (1 from each pyruvate molecule)
• 26 - 28 ATP produced *Note this is variable and the theoretical amount often isn't the same as the actual amount*
• Aerobic Cellular Respiration


  C6H12O6 + 6O2 -> 6CO2 + 6H2O + 30-32 ATP
• 3rd stage: ELECTRON TRANSPORT CHAIN


  1. Occurs on the cristae (folds) of mitochondria

  2. Oxygen used

  3. Enzymes on cristae called cytochromes act as electron carriers

  4. Electrons passed from one carrier to the next, losing energy as they go

  5. Proton gradient formed -> this allows production of ATP as protons (H+) diffuse through ATP Synthase – kinetic energy transformed and used to phosphorylate ADP

  6. Oxygen is the final acceptor –it accepts spent electrons and combines with hydrogen to produce water

  7. 26-28 ATP produced
• 2nd stage: KREB'S CYCLE

  1. Occurs in mitochondria matrix

  2. Oxygen must be present, but IS NOT directly used

  3. Produces 2 ATP (1 from each pyruvate molecule)

  4. Carbon and oxygen from glucose lost here as CO2

  5. Output is H+

  6. NAD and FAD carry H+ and electrons over to the Electron Transport Chain (NADH and FADH)
• 1st stage: GLYCOLYSIS


  1. Occurs in cytosol of cell (not in mitochondria)

  2. Does not require O2

  3. Produces 2 ATP molecules

  4. NAD collects H+ (NADH)

  5. Glucose broken down into 2 (3-carbon) PYRUVATE molecules
• WHY is H ion build up an issue?
• PROCESS


  • GLYCOLYSIS
  • KREB'S CYCLE
  • ELECTRON TRANSPORT CHAIN
• PART OF PROCESS


  • Cytosol
  • Matrix
  • Cristae
• INPUT


  • Glucose
  • ADP
  • NAD
  • FAD
  • OXYGEN
  • NADH
  • FADH
• OUTPUT


  • Pyruvate
  • 2ATP
  • NADH
  • CO2
  • 2ATP
  • NADH
  • FADH
  • WATER
  • 26-28 ATP
  • NAD
  • FAD
• Equation: C6H12O6 + 6O2 -> 6CO2 + 6H2O + 30-32 ATP