L5 mitochondria

• mitochondria are site of

  respiration
• structure of the mitochondria:

  • inner and outer membrane
  • inner membrane forms into cristae
  • matrix is inside the inner membrane
  • inter-membrane space is between the inner and outer membrane
• movement of mitochondria:

  • move by microtubules of the cytoskeleton
  • found in regions of high ATP consumption e.g. myofibrils of muscle cells
• outer membrane contains porin, which make large aqueous _


  channels
• channels on surface of outer membrane allow movement of metabolites into the _

  mitochondria
• _ is the energy currency of the cell

  ATP
• ATP role:

  • transport (active/movement of proteins)
  • mechanical (motor proteins)
  • chemical (reactants)
• mitochondria are the site of _

  cellular respiration
• inner membrane contains 3 major types of membrane complexes

  1. electron transport chain
  2. ATP synthase
  3. specific transporters of metabolites which vary according to cell/tissue type
• cristae is important because:

  • increases membrane surface area
  • energy transducing membrane
  • impermeable to most small ions
• matrix contains:

  • enzymes which catalyse Krebs cycle and fatty acid
  • ribosomes
  • mitochondrial DNA
• high energy electrons used by the mitochondria come from:

  organic molecules
• ATP stores energy:

  in its bonds, breaking one releases energy
• ATP role:

  energy currency
• substrate level phosphorylation process: ADP and an inorganic phosphate are added to form ATP
• electron carriers NAD and FAD role:

  • accept high energy electrons from organic molecules
  • donate them to the electron transport chain
  • cannot be transported in/out of the mitochondria directly so must be regenerated
• where is the electron transport chain?

  located in the inner membrane of the mitochondria
• glycolysis:

  • 2 glucose molecules (6C) are broken down into 2 pyruvate molecules (3C)
  • ATP produced and used up (net=0)
  • high energy electrons passed onto electron carrier NAD+ to generate NADH
• link reaction:

  • enters the mitochondria (from cytosol)->transport protein
  • CO2 molecule removed from pyruvate
  • coenzyme A added to form Acetyl Co A
• Krebs cycle:

  • Acetyl CoA enters cycle
  • loss of carbon (2 CO2)
  • 1 ATP per acetyl CoA
  • production of NADH and FADH2 at multiple steps in the cycle
• FAD accepts electrons of slightly _ energy than NAD+

  lower
• (electron transport chain) energy generated through:

  redox reactions
• release of energy when electron moves down the chain as:

  reactant oxidised and product is reduced
• components of the electron transport chain:

  • multiprotein complexes in inner membrane
  • proteins have prosthetic group (catalytic function)
  • downhill neighbour in the electron transport chain always has slightly higher affinity (more electronegative) for the electron
• what molecules are in the electron transport chain?

  • flavoprotein
  • iron-sulfur protein
  • ubiquinone
  • cytochromes

  
• the last electron acceptor is _, which bonds with a pair of H+ to make _

  oxygen and water
• ATP synthase role:

  convert ATP to ADP and inorganic phosphate (releasing energy)
• structure of ATP synthase:

  • large multiprotein complex
  • mushroom-like appearance
  • F0 portion is H+ channel
  • F1 head is site of ATP synthesis
• how ATP synthase works?

  • movement of H+ through channel causes
  • rotation of rotor and central stalk
  • forces conformational changes in central stalk and F1
  • provides energy for ATP synthesis
  • 10 H+ moving back to matrix, 3 ATP molecules are generated
• mitochondrial poisons:

  cyanide prevents electrons from one of the cytochromes
• mitochondria are not found in all eukaryotes 


  e.g. human red blood cells
• inner mitochondrial membrane is the location of the _


  electron transport chain
• an electron _ energy when it shifts from a less electronegative atom to a more electronegative one

  loses
• oxidative phosphorylation requires a proton gradient to be established between the intermembrane space and the _

  matrix
• ATP synthase _ portion is a proton channel

  F0