Lecture 4

Question 1

What type of reaction is one that breaks down bigger molecules into smaller ones?

Answer 1

An exergonic reaction

Question 2

What type of reaction is one that builds up bigger molecules from smaller ones?

Answer 2

An endergonic reaction

Question 3

Which reaction is more favourable, and exergonic or an endergonic one?

Answer 3

Exergonic - breaking down bigger molecules to smaller ones

Question 4

What does it mean if Gibbs free energy (delta G) is below 0?

Answer 4

It means that the reaction is favourable and will happen spontaneously

Question 5

What does it mean if Gibbs free energy (delta G) is above 0?

Answer 5

It means that the reaction will not happen spontaneously and it requires energy input

Question 6

What are the 2 steps that comprise oxidatitive phosphorylation?

Answer 6

• The electron transport chain

- Chemiosmosis

Question 7

Where do these metabolic processes take place:

• Glycolysis
• Krebs cycle
• Electron transport chain

Answer 7

• Glycolysis - in the cytoplasm of a cell
• Krebs cycle - in the matrix of the mitochondria
• Electron transport chain - in the outer membrane of the mitochondria

Question 8

What is the process called that takes pyruvate to Acetyl Co?

Answer 8

Oxidative decarboxylation

Question 9

What is a reaction know as if it involves both anabolism and catabolism?

Answer 9

An amphibolic reaction

Question 10

What is a refuelling/ self replenishing reaction called?

Answer 10

An anaplerotic reaction

Question 11

What does the electron transport chain create that drives oxidative phosphorylation?

Answer 11

It creates a chemiosmotic gradient

Question 12

What ion gradient is used in oxidative phosphorylation and what does it help to form?

Answer 12

The Hydrogen ion gradient that was formed by the ETC is used by ATP synthase to form ATP

Question 13

What is happening during the ETC?

Answer 13

H+ ions are being pumped out of the matrix of the mitochondria and into the intermembrane space creating an unbalancing of the charges of the 2 places over the membrane

Question 14

What are the four complexes involved in the ETC and what do they all do?

Answer 14

• Complex I - Passes e- and pumps out H+
• Complex II - Passes e- but DOESNT pump out H+
• Complex III - Passes e- and pumps out H+
• Complex IV - Passes e- and pumps out H+

Question 15

What are the 4 complexes in the ETC called?

Answer 15

I - NAD dehydrogenase
II - Succinate Q reductase
III - Cytochrome C Bc1
IV - Cytochrome C Oxidase

Question 16

What happens at the first complex?

Answer 16

• NAD is fed into he complex (2NADH—> 2NAD+ +2H+)
• Both of the e- are transferred to ubiquinone where a reaction happens ( 2e- + CoQ —> reduced CoQ
• Both of the protons (H+) are pumped across the IMM into the IMS

Question 17

What happens at complex 2 of the ETC?

Answer 17

• FADH2 is fed into the complex (FADH2 —> +2H+ +2e-

- However being the 2nd complex of the ETC the protons DO NOT get pumped across the IMM

Question 18

What happens at complex 3 of the ETC?

Answer 18

• The e- taken from reduced CoQ (reduced CoQ[2e-] —> CoQ +2e-)
• The CoQ (ubiquinone) then goes back to complex to to complete the cycle again
• 2 H+ are pumped out of the IMM into the IMS

Question 19

What happens at complex 4 of the ETC?

Answer 19

• (O2 + 4H+ + 4e- —>2H20)

- It also pumps H+ ions across the IMM into the IMS