18.4 Oxidative Phosphorylation

Question 1

What happens to the hydrogen atoms collected by NADH and FADH2?

Answer 1

They are delivered to electron transport chains

Question 2

Where are the electron transport chains located?

Answer 2

In the membranes of the cristae of the mitochondria

Question 3

What do hydrogen atoms dissociate into?

Answer 3

H+ ions and an electron

Question 4

What happens to the electrons at the end of the electron transport chain?

Answer 4

They combine with hydrogen ions and oxygen to form water.

Question 5

Describe what happens as the electrons travel through the electron transport chain.

Answer 5

• High energy electrons release their energy as they move along an electron transport chain
• Energy is used to actively transport protons across the mitochondrial membrane, into the intermembrane space
• H+ accumulates in the inter-membrane space, creating a high conc. of protons across the membrane
• Protons diffuse back into the membrane/matrix through ATP synthase channnels, bound to ADP and Pi
• ATP synthesised by chemiosmosis.

Question 6

What it meant by oxygen being the terminal acceptor of electrons?

Answer 6

At the end of the electron transport chain, the electron is accepted by an oxygen

Question 7

What would happen if no oxygen was present during oxidative phosphorylation?

Answer 7

• The electrons wouldn’t be able to leave the electron transport chain, so no new ones could enter, so no ATP synthesised
• NADH and FADH2 can’t release their H atoms

Question 8

What is substrate level phosphorylation?

Answer 8

Production of ATP involving the transfer of a phosphate group from an intermediate (not involving an electrochemical gradient)

Question 9

State the differences between oxidative and substrate level phosphorylation.

Answer 9

• OP occurs in electron transport chain, SLP occurs in glycolysis and krebs cycle
• OP, oxygen required, SLP oxygen not required
• OP proton gradient required, SLP proton gradient not required

Question 10

What are the ways of measuring the rate of respiration?

Answer 10

• Measure rate of uptake of oxygen by a respiring organism (respirometer)
• Measure volume of product released in a given time (i.e CO2)
• Use a redox indicator (i.e methylene blue, goes from blue to colourless as it is reduced)