4. Metabolic pathways and ATP production II Flashcards Preview

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Flashcards in 4. Metabolic pathways and ATP production II Deck (25)
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1
Q

What is the significance of the high energy thioester bond in Acetyl CoA?

A

Readily hydrolysed

Enables acetyl CoA to donate acetate (2C)

2
Q

What is the Krebs cycle also known as?

A

The Tricarboxylic Acid Cycle (TCA)

The Citric acid cycle

3
Q

What is produced in each turn of the TCA cycle?

A

2 x CO2
3 x NADH
1 x GTP
1 x FADH2

4
Q

Where are the Krebs’ Cycle enzymes found?

A

Mitochondrial Matrix

5
Q

Which Krebs’ Cycle enzyme is not found in the mitochondrial matrix and where is it?

A

Succinate Dehydrogenase

In inner mitochondrial membrane

6
Q

What conditions are required for the TCA cycle?

A

Aerobic

As to regenerate NAD+ and FAD, oxidation is required

7
Q

What occurs in degradation of amino acids?

A

Amino group removed, excreted as urea

Carbon skeleton used for production of glucose or fed into TCA cycle

8
Q

What 7 molecules can be produced from degradation of amino acids?

A
Pyruvate
Acetyl CoA
Acetoacetyl CoA
Alpha- Ketoglutarate
Succinyl CoA
Fumarate
Oxaloacetate
9
Q

What occurs in a transamination reaction?

A

Amine group is transferred from an amino acid to a keto acid

Produces a new pair of amino and keto acids

10
Q

Give an example of transamination

A

alanine + alpha-ketoglutarate
->
pyruvate + glutamate
(enzyme = alanine aminotransferase)

11
Q

Why does NADH produced in glycolysis need to enter the mitochondria?

A

To be used in oxidative phosphorylation, to regenerate NAD+

12
Q

What are the 2 ways of electrons from NADH entering the mitochondrial matrix?
Where are these 2 transport mechanisms found?

A

Glycerol Phosphate Shuttle – skeletal muscle, brain

Malate-Aspartate Shuttle – liver, kidney, heart

13
Q

Describe the glycerol phosphate shuttle.

A

Cytoplasmic glycerol-3-phosphate dehydrogenase transfers electrons from NADH to DHAP: converting it to glycerol-3-phosphate
Glycerol-3-phosphate is converted by mitochondrial glycerol-3-phosphate dehydrogenase back into DHAP and the electrons are passed via FAD to coenzyme Q

14
Q

What does DHAP stand for?

A

Dihydroxyacetone phosphate

15
Q

Describe the malate-aspartate shuttle.

A

H- transferred from cytoplasmic NADH to oxaloacetate, forms malate
Malate transported into mitochondria, rapidly re-oxidised by NAD+, forms oxaloacetate + NADH

16
Q

What are the components of the malate-aspartate shuttle?

A

2 Membrane carriers

4 Enzymes

17
Q

What are the 2 membrane carriers in the malate-aspartate shuttle?

A

Alpha-ketoglutarate transporter: Exchanges alpha-ketoglutarate for malate
Glutamate/ Aspartate transporter: Exchanges aspartate for glutamate

18
Q

What different types of reactions are NADPH and NADH involved in?

A
NADPH = Anabolic 
NADH = Catabolic
19
Q

What can oxidative phosphorylation of NADH produce?

A

3 X ATP

20
Q

What can oxidative phosphorylation of FADH2 produce?

A

2 X ATP

21
Q

How many ATP are produced from oxidation of Acetyl CoA?

A

12 ATP

From: 3 NADH + 1 FADH + 1 GTP

22
Q

What is the theoretical maximum yield of ATP from 1 molecule of glucose?

A

38

23
Q

What is the difference between NADP+ and NAD+?

A

NADP+ has 1 more phosphate group

So binds to different enzymes

24
Q

What does having different cofactors in different reactions allow?

A

Electron transport in catabolism to be kept separate to anabolism

25
Q

What is NADPH used as?

A

Cofactor in cholesterol biosynthesis

C=C reduced by transfer of hydride ion