Oxidative Phosphoroyation

Question 1

Where does this part of the reaction occur?

Answer 1

Cristae of mitochondria

Question 2

What is the structure of the Cristae?

Answer 2

• folded
• increased surface area

Question 3

What does oxidative phosphorlyation mean?

Answer 3

• It means adding inorganic phosphate (Pi) to ADP in the presence of oxygen to make ATP (not directly), via a chain of electron carriers

Question 4

What are the carriers like?

Answer 4

• The carriers are a sequence of proteins embedded into the membrane making up the cristae

Question 5

What enzyme is involved?

Answer 5

• ATP synthase

Question 6

Why is the cristae folded?

Answer 6

• It gives a large surface area
• for as much ATP to be made

Question 7

What are the steps of oxidative phosphorlyation?

Answer 7

• Reduced NAD and Reduced FAD are re-oxidised back to NAD/FAD when they release their hydrogen atoms next to the cristae
• these hydrogen atoms then split into protons (H+) and electrons.
• H+ are in the solution in the mitochondrial matrix near the cristae
• Electrons are passed along the protein carriers on the cristae. Each carrier contains an iron ion. When it picks up electrons, it is reduced to Fe2+ and when it passes it on, it is re-oxidised to Fe3+.
• As electrons pass along the chain, energy is released. This is used to pump H+ ions acroos the inner mitochondrial membrane (cristae) into the inter-membrane space.
• As H+ accumulates in the inter-membrane space, this creates a proton gradient across the membrane (H+).
• This builds up a proton motive force/chemoismotic potential.
• the inner membrane of the mitochondria is not freely permeable to H+ ions, but they can diffuse back into the matrix via special protein channels associated with the enzyme ATP synthase
• The flow of H+ ions through these channels are called chemiosmosis and it changes the shape of the ATP synthase enzyme, activating it.
• This allows ADP to join with Pi to make ATP (Phosphorlyation)

Question 8

What is chemiosmosis?

Answer 8

The flow of H+ ions through these channels are called chemiosmosis and it changes the shape of the ATP synthase enzyme, activating it.

Question 9

What is the final acceptor molecule?

Answer 9

• oxygen

Question 10

Why is oxygen the final acceptor molecule?

Answer 10

• It picks up electrons coming out of the chain along with the hydrogen from chemiosmosis to form water

Question 11

What is the final product of aerobic respiraion?

Answer 11

• water

Question 12

What is the evidence for the process of chemiosismosis?

Answer 12

• The PH difference across the two sides of the inner mitochondrial membrane
• H+ ions create an acidic PH