Oxidative Phosphorylation

1
Oxidative Phosphorylation

• Describe the process of oxidative
  phosphorylation, with reference to the roles of
  electron carriers, oxygen and the mitochondrial
  cristae
• Explain that oxygen is the final electron
  acceptor in aerobic respiration

2
Oxidative Phosphorylation happens via the
electron transport chain

• All the products from the previous stages are
  used in this final stage. Its purpose is to
  transfer the energy from molecules made in
  glycolysis, the link reaction and the Krebs
  cycle to ADP. This forms ATP, which can then
  deliver the energy to parts of the cell that need
  it. The synthesis of ATP as a result of the
  energy released by the electron transport chain
  is called oxidative phosphorylation
• The electron transport chain is where most of the
  ATP from respiration is produced. In the whole
  process of aerobic respiration, 32 ATP molecules
  are produced from one molecule of glucose 2 ATP
  in glycolysis, 2 ATP in the Krebs cycle and 28
  ATP in the electron transport chain
• The electron transport chain also reoxidises NAD
  and FAD so they can be reused in previous steps

3
Respiration The 4 Parts

• Respiration consists of 4 parts
• Glycolysis
• Link Reaction
• Krebs Cycle
• Oxidative Phosphorylation (the electron transport
  chain)

4
Oxidative Phosphorylation produces lots of ATP

• The energy needed for ATP synthesis is provided
  by the electron transport chain. It uses the
  reduced NAD and FAD from the previous 3 stages to
  produce 28 molecules of ATP for every molecule of
  glucose

5
Whats going on?

• It involves electron carriers embedded in the
  inner mitochondrial membranes
• They are folded into cristae which increases the
  surface area (providing more electron carriers)
• The electrons are passed along a chain of
  electron carriers and then donated to oxygen the
  final hydrogen acceptor

6
Whats the point?

• As electrons flow along the electron transport
  chain, energy is released and used by coenzymes
  associated with proteins 1, 3 and 4 to pump
  protons across the intermembrane space
• This builds up a proton gradient which is also a
  pH gradient (lowers the pH) and an
  electrochemical gradient
• The hydrogens can only get back through the ion
  channel which is associated with ATP synthase
• The flow of hydrogen ions through this ion
  channel is called chemiosmosis

7
H
Outer membrane of mitochondrion
H
H
H
H
H
H
Intermembrane space
Stalked particle
Inner membrane of mitochondrion
ATPsynthase
Carrier 2
Carrier 3
Carrier 4
Carrier 1
2e-
ADP Pi
2e-
H
H
2H
H
NADH H
2H2O
ATP
2H
H
NAD
O2 2H
Matrix of mitochondrion
8
Oxidative Phosphorylation produces lots of ATP

• 1. Hydrogen atoms are released from NADH H and
  FADH2 (as they are oxidised to NAD and FAD). The
  H atoms split to produce protons (H) and
  electrons (e-) for the chain.
• The electrons move along the electron chain (made
  up of three electron carriers) losing energy at
  each level. This energy is used to pump the
  protons (H) into the space between the inner and
  outer mitochondrial membranes (the intermembrane
  space)

9
Oxidative Phosphorylation produces lots of ATP

• The concentration of protons is higher in the
  intermembrane space than in the mitochondrial
  matrix, so an electrochemical gradient exists.
• The protons then move back through the inner
  membrane down the electrochemical gradient,
  through specific channels on the stalked
  particles of the cristae- this drives the enzyme
  ATP synthase. By spinning like a motor, this
  enzyme supplies electrical potential energy to
  make ATP from ADP and inorganic phosphate
• The protons and electrons recombine to form
  hydrogen, and this combines with molecular oxygen
  (from the blood) at the end of the transport
  chain to form water. Oxygen is said to be the
  final electron acceptor

10
The Importance of Oxygen

• We have learned that oxygen is the final hydrogen
  acceptor in respiration
• We are now gong to look at the uptake of oxygen
  by respiring organisms

11
(No Transcript)
12
(No Transcript)
13
(No Transcript)
14
(No Transcript)
15
Plenary

• Complete the missing word sheet