Mitochondria and Oxidative Phosphorylation

Question 1

How many ATP does one NADH produce in the ETC?

Answer 1

3

Question 2

How many ATP does one FADH2 produce in the ETC?

Answer 2

2

Question 3

How are mitochondria inherited?

Answer 3

Maternally

Question 4

What are 5 pieces of evidence supporting the endosymbiosis theory?

Answer 4

Mitochondria only arise from preexisting mitochondria.
Mitochondria have their own genome which resembles prokaryotes.
Mitochondria have their own protein synthesising machinery which resembles prokaryotes.
The first amino acid of their transcripts is fMet which is the same as in bacteria.
A number of antibiotics bock protein synthesis in mitochondria.

Question 5

What is the route for electrons in the ETC?

Answer 5

NADH dehydrogenase complex –> ubiquinone/coenzyme Q –> cytochrome bc1 complex –> cytochrome C –> cytochrome oxidase –> oxygen

Question 6

What allows the flow of the electrons in a logical order?

Answer 6

The fact that each unit in the chain has a higher affinity for electrons/has a higher redox potential (more positive)

Question 7

What is the redox potential?

Answer 7

The ability of a redox couple to accept or donate electrons.

Question 8

What does a negative redox potential suggest?

Answer 8

An ability to donate

Question 9

What does a positive redox potential suggest?

Answer 9

Ability to accept

Question 10

Which is the membrane bound part and which projects into the mitochondrial space of ATP synthase, F0 or F1?

Answer 10

F0 - membrane bound, F1 - projects.

Question 11

Which subunit acts as an axle in F1?

Answer 11

Gamma

Question 12

Which subunit undergoes structural changes due to gamma axle rotating?

Answer 12

Beta

Question 13

Why does FADH2 make less ATP?

Answer 13

Because it passes its electrons directly to ubiquinone

Question 14

Name 5 metabolic poisons

Answer 14

Cyanide, carbon monoxide, malonate, oligomycin and dinitrophenol

Question 15

Explain the mechanism of cyanide

Answer 15

Binds with high affinity to the ferric (Fe3+) form of the ferric group of cytochrome oxidase and inhibits it, blocking the flow of electrons

Question 16

Explain the mechanism of carbon monoxide

Answer 16

Binds to haemoglobin stronger than oxygen so oxygen is not supplied to the body

Question 17

Explain the mechanism of malonate

Answer 17

Resembles succinate so acts as a competitive inhibitor and slows down the flow of electrons from succinate to ubiquinone by inhibiting oxidation of succinate to fumarate

Question 18

Explain the mechanism of oligomycin

Answer 18

Binds to the stalk (gamma subunit) of ATP synthase and blocks the flow of protons through the enzyme

Question 19

Explain the mechanism of dinitrophenol

Answer 19

Induces weight loss by transporting protons across the mitochondrial membrane thereby uncoupling oxidative phosphorylation from ATP production and therefore increasing metabolic rate and body temperature

Question 20

Which metabolic poison uncouples ATP production from oxidative phosphorylation?

Answer 20

Dinitrophenol

Question 21

Which metabolic poison binds to the stalk (gamma subunit) of ATP synthase?

Answer 21

Oligomycin

Question 22

Which metabolic poison inhibits succinate dehydrogenase?

Answer 22

Malonate

Question 23

Which metabolic poison binds to haemoglobin?

Answer 23

Carbon monoxide

Question 24

Which metabolic poison binds cytochrome oxidase and inhibits it?

Answer 24

Cyanide