MEH Energy Production ( Respiration)

Question 1

Define cellular respiration

Answer 1

Cellular respiration is the process in which cells break down macromolecules like glucose to produce ATP. An energy currency for the cell.

Question 2

Name the three stages in cellular respiration

Answer 2

1. Glycolysis
2. The Krebs cycle (TCA)
3. The electron transport chain ( oxidative phosphorylation

Question 3

Where does glycolysis take place

Answer 3

Cytosol- the soluble portion of a cells cytoplasm

Question 4

Describe the input and products of Glycolysis

Answer 4

Glucose + 2ATP = 4ATP + 2NADH + 2 Pyruvate

Net ATP production = 2

Question 5

What is the product of oxidation of Pyruvate

Answer 5

2 x Acetyl CoA and 2 NADH

Question 6

Where does pyruvate oxidation and the Krebs cycle take place

Answer 6

In the mitochondria

Question 7

Explain the input and products of the Krebs cycle

Answer 7

Each Acetyyl coA (there are 2 produced) enters the Krebs cycle separately.

Acetyl CoA—> 3NADH + FADH2 + GTP.

So total products 6NADH + 2FADH2 + 2GTP

Question 8

What are the intermediates that feed into the ETC.

Answer 8

NADH and FADH2

Question 9

State the approximate yield of ATP from both NADH and FADH2 in the ETC

What is he reason for the difference?

Answer 9

1 NADH= 2.5 ATP
1 FADH2 = 1.5 ATP

NADH carries more energy than FADH2 Therefore NADH is high enough energy to go through the first PTC so goes through 3 PTC’s. FADH2 only has enough energy to go through 2 PTC’s does not go through the first one.

Greater p.m.f ( electrochemical gradient) = more ATP produced.

Question 10

Explain how the ETC and ATP production are coupled

Answer 10

ATP generation is dependant on the gradient of protons.
No proton gradient = no ATP generated.

Question 11

Describe the function of uncouplers

Answer 11

Uncouplers increase the permeability of the membrane and so dissipate the proton gradient as protons can re-enter the mitochondria not through the ATPase. P.m.f is reduced.

No drive for ATP synthesis.

Question 12

Why does energy produced from ox phos need to be stored?

Answer 12

If energy is not stored as ATP- it is lost as heat energy.

Question 13

Explain how cyanide or carbon monoxide work to inhibit the ETC

Answer 13

These molecules block the flow of electrons.
No electron transport occurs
No oxidative phosphorylation

Question 14

Explain how diseases can be associated with oxidative phosphorylation

Answer 14

Gene mutations in mitochondria DNA can cause defects in PTC and ATPsynthase.

May not function correctly/be absent.
Decrease in electron transport
Decrease in ATP synthesis.

Question 15

What is the function of pyruvate dehydrogenase.

Answer 15

It is an enzyme that catalyses the conversion of pyruvate to Acetyl CoA

Question 16

Explain the role of NAD+ in the production of Acetyl CoA

Answer 16

NAD+ is a co factor to pyruvate dehydrogenase.
That is reduced into NADH as pyruvate is oxidised.

Question 17

Name one other product that is produced in the creation of Acetyl CoA.

Answer 17

Carbon dioxide

Question 18

Explain why fatty acids cannot contribute tot he production of glucose.

Answer 18

fatty acids can contribute to production of Acetyl CoA when broken down.

Pyruvate to Acetyl CoA reaction is irreversible.

Therefore the Acetyl CoA produced by fatty acids cannot be converted to pyruvate.

Fatty aids Cannot contribute to gluconeogenesis.

Question 19

Other than feeding into the citric acid cycle give another function of Acetyl CoA.

Answer 19

Acetyl CoA can be used to produce fatty acids when ATP levels are high.

Question 20

What is Allosteric regulation

Answer 20

Allo= other
Steric= site
Allosteric regulation involved a molecule that binds on another site ( regulatory site) of an enzyme to activate or inhibit it.

Question 21

Explain how ATP is an allosteric inhibitor in the regulation of pyruvate dehydrogenase reaction to create Acetyl CoA

Answer 21

If ATP levels are high, the conversion of pyruvate to Acetyl CoA will reduce.

Has Enough Acetyl CoA to be fed into the Krebs cycle and ultimately produce ATP.