module 5 - 18.4 oxidative phosphorylation

Question 1

what is ATP synthase?

Answer 1

• an enzyme that catalyses the formation of ATP using ADP and an inorganic phosphate, Pi
• is a molecular machine

Question 2

why is the formation of ATP from ADP + Pi energetically unfavourable?

Answer 2

takes in lots of energy

Question 3

what does ATP ensure for the reaction?

Answer 3

that the reaction goes in a forward direction

Question 4

what are the sources of energy used to make the reaction move in a forward direction?

Answer 4

• an electrochemical gradient created by the difference in proton or H+ conc. across inner mitochondrial membrane
• the protons diffuse back into the matrix by diffusing through ATP synthase, which supplies energy to reaction of ADP +Pi to make ATP

Question 5

what is chemiosmosis?

Answer 5

the movement of ions across a semipermeable membrane bound structure, down their electrochemical gradient e.g ATP

Question 6

what are NAD/FAD?

Answer 6

reduced enzymes

Question 7

what is the acidity like in the inner membrane of the mitochondria?

Answer 7

very acidic

Question 8

where is the electron transport chain?

Answer 8

• takes place in the cristae
• oxygen must be present to be able to accept the electrons

Question 9

what is the mechanism for producing ATP called?

Answer 9

oxidative phosphorylation

Question 10

how many ATP molecules come from oxidative phosphorylation?

Answer 10

34/38
(2 from krebs cycle, 2 from glycolysis)

Question 11

what is the electron transport chain?

Answer 11

• electron carrier proteins are in inner mitochondrial membrane
• transport high energy electrons between themselves and pump protons to inter-membrane space of mitochondrion
• creates electrochemical proton gradient across inner mitochondrial membrane
• the high energy electrons come from reduced NAD and reduced FAD
• final low energy electrons accepted by free oxygen forming water
• oxygen is final electron acceptor

Question 12

what are protons?

Answer 12

hydrogen atoms left on glucose molecules

Question 13

what are cytochromes?

Answer 13

carriers, conjugated proteins

Question 14

when can aerobic respiration only occur?

Answer 14

only happens if free oxygen is present in mitochondria

Question 15

what happens to reduced NAD and reduced FAD during the electron transport chain?

Answer 15

• deliver high energy electrons to electron transport chain

Question 16

what happens after reduced NAD and reduced FAD deliver high energy electrons to electron transport chain?

Answer 16

as electron is passed through the proteins, energy is used to pump protons into inter membrane space

Question 17

how is energy generated during electron transport chain?

Answer 17

generated as hydrogen ions (protons) unite to form water, 2 more ATP molecules made

Question 18

how many ATP molecules are made by one reduced NAD?

Answer 18

3 ATP molecules formed by oxidative phosphorylation

Question 19

which reactions occur down the length of the chain?

Answer 19

redox reactions

Question 20

what is oxidative phosphorylation?

Answer 20

ATP synthesis using a flow of protons down a conc. gradient through ATP synthase

Question 21

what does ATP synthase do?

Answer 21

the protons in the inter-membrane space diffuse down the conc. gradient through ATP synthase by facilitated diffusion

Question 22

what does the facilitated diffusion produce?

Answer 22

water by condensation reaction

Question 23

what is FAD?

Answer 23

• carried hydrogen to electron transport chain
• delivers its pairs of hydrogen atoms to a carrier further down the chain than reduced NAD
• generates 2 ATP molecules

Question 24

what is the net production of ATP?

Answer 24

38

Question 24

where does the net production of ATP come from?

Answer 24

10 reduced NAD yield 30 ATP
4 reduced FAD yield 2 ATP