respiration

• suggest and explain why cheese has the highest energy content (3)

  • highest lipid content
  • has the highest proportion of C-H bonds
  • can be oxidised more and go through many turns of the Krebs cycle
  • producing more NADH
• what does the acetyl group from the link reaction bind to and form (2)

  • oxloacetate
  • citrate
• define substrate level phosphorylation and where does it occur (2)

  • transfer of Pi group from intermediate , without energy from an electron transport chain
  • creatine phosphate
  • Krebs cycle when 4C compound is being rearranged
  • glycolysis when triose biphosphate is turned into pyruvate X4 ATP formed
• when using a respirometer how would you add red fluid into the capillary tube (1)

  • dipped into a small beaker and allowed to run
• during chemiosmosis where and to are protons pumped from

  • matrix
  • inter membrane space
• where does each stage of respiration occur (4)

  • glycolysis : cytoplasm of cell
  • link reaction : matrix
  • Krebs cycle : matrix
  • oxidative phosphorylation : inner mitochondrial membrane
• why is the yield of ATP fewer than the theoretical (4)

  • ATP used to transport pyruvate and NADH from glycolysis across plasma membrane of mitochondria
  • not all NADH and FADH oxidised
  • some H+ leaks back into matrix
  • some energy from ETC lost as heat energy
• why is anaerobic respiration in animals reversible whereas in yeast cells it is not ?

  • pyruvate -> lactate is one step and can be reversed by lactate dehydrogenase
  • pyruvate -> ethanal -> ethanol is 2 steps , carboxylase cannot reverse it ,loses a carbon atom in the form of Co2
• outline the process of glycolysis

  • glucose -> bihexosephosphate using 2 ATP
  • hexose biphosphate -> 2X triosephosphate
  • 2X triosephosphate -> 2X triosebiphosphate
  • 2X triosebiphosphate -> 2X pyruvate
  • NET 2 ATP and 2 NADH
• suggest why lactate is metabolised by hepatocytes instead of respiring cells

  • they can tolerate low PH
  • they have the right enzymes
  • have O2 supply which is needed to convert into pyruvate
• describe the process of lactate fermentation

  • pyruvate oxidised to lactate
  • catalysed by lactate dehydrogenase
  • NADH -> NAD
  • reversible
• process of the link reaction

  • 3C pyruvate -> 2C acetyl group
  • CO2 + NADH formed
  • transported to Krebs cycle by CoA