Respiration

• where does aerobic respiration take place?

  mitochondria
• structure of mitochondria

  2 phospholipid membranes

  -outer is smooth and permeable to small molecules

  -inner is folded (high SA), less permeable and the site of the electron transport chains (many as cristae has high SA)
• where does glycolysis take place?

  cell cytoplasm
• where does the link reaction take place?

  matrix of mitochondria
• where does the krebs cycle take place?

  matrix of mitochondria
• where does oxidative phosphorylation take place?

  inner membrane of mitochondria
• simple description of glycolysis

  phosphorylation and splitting of glucose
• simple description of link reaction

  decarboxylation and dehydrogenation of pyruvate
• simple description of krebs cycle

  cyclical pathway with enzyme controlled reactions
• simple description of oxidative phosphorylation

  production of ATP through oxidation of hydrogen atoms
• what does glycolysis produce?

  2 pyruvate, 2 NADH, 2 ATP (net gain)
• step 1 of glycolysis name

  phosphorylation
• what happens in phosphorylation during glycolysis?

  glucose is phosphorylated by 2 molecules of ATP to produce glucose phosphate
• step 2 of glycolysis


  lysis
• what happens during step 2 (lysis) of glycolysis?

  glucose phosphate splits into 2 molecules of triose phosphate
• what is step 3 of glycolysis?

  oxidation

  dephosphorylation
• what happens during step 3 (oxidation/dephosphorylation) of glycolysis?

  -Hydrogen removed from each molecule to triose phosphate to produce 2 molecules of NADH

  -phosphates are used to form 4 molecules of ATP

  -2 molecules of pyruvate are produced
• what is needed for pyruvate to enter the mitochondrial matrix and continue aerobic respiration

  oxygen
• how does pyruvate move across the double membrane of the mitochondria?

  via active transport
• what does the link reaction produce?

  Acetyl CoA

  CO2

  NADH
• step 1 of the link reaction

  pyruvate is oxidised by enzymes to produce acetate and carbon dioxide (decarboxylation)

  NAD is also reduced to NADH (dehydrogenation)
• step 2 of the link reaction

  acetate combines with coenzyme A to form acetyl CoA
• Role of CoA

  transports the acetyl group to the krebs cycle, links glycolysis in the cytoplasm to later stages of respiration in the mitochondria
• Step 1 of Krebs Cycle

  Acetyle CoA (2C) enters the cycle from the link reaction
• Step 2 of the Krebs Cycle

  oxaloacetate (4C) accepts the 2C acetyl fragment from acetyl CoA to form citrate (6C)

  -Coenzyme A is released and goes back to the link reaction
• Step 3 of the Krebs Cycle

  Citrate is converted back into oxaloacetate through a series of redox reactions

  -citrate is decarboxylated releasing 2 CO2

  -Citrate is oxidised, releasing H atoms that reduce NAD and FAD to NADH and FADH2

  -a phosphate is transferred from one of the intermediates to ADP forming ATP
• Products of the Krebs Cycle

  2 CO2, 3 NADH, 1 FADH2, 1 ATP
• role of coenzymes NAD and FAD


  accept the hydrogen atoms that become available during respiration and transfer them to the electron transport train where the hydrogen atoms are removed and the coenzymes are oxidised
• where is NADH produced in respiration

  2 molecules from glycolysis

  2 molecules from the link reaction

  6 molecules from the krebs cycle

  
  

  1or3 from each cycle/reaction as glucose is split into 2 during glycolysis
• where is FADH2 produced in respiration?

  2 molecules from the krebs cycle

  
  

  1 from each cycle as glucose is split into 2 during glycolysis
• chemiosmotic theory

  -energy from electrons is passed through a chain of proteins in the membrane is used to pump protons (H+) up their concentration gradient into the intermembrane space

  -protons (H+) are then allowed to flow by facilitated diffusion through a channel in ATP synthase into the matrix

  -the energy of the hydrogens flowing down their concentration gradient is harnessed resulting in the phosphorylation of ADP into ATP by ATP synthase
• Oxidative phosphorylation process

  -Hydrogen atoms are donated by NADH and FADH2 from the krebs cycle

  -Hydrogen atoms split into protons and electrons

  -high energy electrons enter the electron transport chain and release energy as they move through the electron transport chain

  -the energy released is used to transport protons across the inner mitochondrial membrane from the matrix to the intermembrane space

  -A concentration gradient of protons is established between the intermembrane space and the matrix

  -The protons return to the matrix via facillitated diffusion through the channel protein ATP synthase

  -the movement of protons down their concentration gradient provides energy for ATP synthesis

  -Oxygen acts as a final electron acceptor and combines with protons and electrons at the end of the electron transport chain to form water
• What is the final electron acceptor

  oxygen
• where are hydrogen atoms donated from in oxidative phosphorylation

  NADH and FADH2
• what are hydrogen atoms split into?

  H+ and e-
• how is a concentration gradient of protons established and maintained between the intermembrane space and the matrix

  energy released from electrons in the electron transport chain is used to transport protons from the matrix into the intermembrane space -moved through by proteins in the electron transport chain(established), protons return to the matrix via facilitated diffusion through ATP synthase (channel protein) (maintained)
• where does the energy for ATP synthesis come from?

  protons moving from the matrix into the intermembrane space down their concentration gradient through the channel protein ATP synthase
• what is the electron transport chain made up of?

  membrane proteins
• how are electrons able to pass from carrier to carrier?

  the proteins are positioned close together
• what happens when there isn't enough oxygen for respiration

  -there is no final acceptor of electrons

  -electron transport chain stops functioning

  -no more ATP produces

  NADH and FADH2 aren't oxidised

  -NAD and FAD aren't available for the Krebs cycle

  -Krebs cycle stops