Metabolism

Question 1

Coenzyme A

Answer 1

Adenosine 3’ phosphate 5’ diphosphate
Pantothenic acid
B-Macaptoethanol
SH= reactive part

Coenzyme A + acetyl group = acetyl coA

Question 2

Breakdown of ethanol (hangovers)

Answer 2

Ethanol (alcohol dehydrogenase, NAD+-NADH) –> Acetaldehyde

Acetaldehyde (aldehyde dehydrogenase NAD+ - NADH) –> Acetate

Antabuse –> treatment of alcoholism

Ethanol is in direct contact with lactate (lactate to pyruvate) therefore ethanol ingestion tends to prevent gluconeogenesis from lactate in the liver

Question 3

Cori Cycle

Answer 3

Lactate to glucose (in liver) Gluconeogenesis
Glucose to lactate (exercising muscles)

Liver produces glucose for exercising muscles from lactate

Question 4

Pyruvate dehydrogenase complex

Answer 4

VERY BIG: 5x106 Da (60pp chains)
Requires: Thiamine pyrophosphate (TPP) VB1
Lipoamine
Flavin adenine dinucleotide (FAD) Vb2 riboflavin

24 Pyruvate dehydrogenase (TPP: oxidative carboxylation of pyruvate)
24 Dihydrolipoyl transacetylase (Lipoamide: transfer of acetyl group to CoA
12 dihydrolipoyl dehydrogenase (FAD: regeneration of oxidised lipoamide)

Question 5

B1 deficiency (beri beri)

Answer 5

Weakness and fatigue, increase in pyruvate

Pyruvate NOT being metabolised

Question 6

Krebs cycle (reactants)

Answer 6

Acetyl coA + Oxaloacetate --> Citrate 
Cis-Aconitase 
Isocitrate 
A-Keta glutarate 
Succinyl CoA
Succinate 
Fumarate 
Malate 
Oxaloacetate

Question 7

2 mobile e- carriers

Answer 7

Coenzyme Q

Cytochrome C

Question 8

Membrane bound complexes

Answer 8

NADH-Q-reductase
Succinate- Q- reductase
Cytochrome reductase
Cytochrome Oxidase

Question 9

How does cytoplasmic NADH get access to the respiratory chain?

Glycerol phosphate SHUFFLE

Answer 9

Inner mitochondrial membrane is not very permeable to NADH

NADH (cytoplasm) + FAD (mito) –> NAD+ (cyto) + FADH2 (mito) –> 2xATP

NADH could potentially make 3ATP but makes two; NADH in wrong compartment

Dihydroxyacetone phosphate, Glycerol 3-phosphate

Question 10

Net yield per glucose:

Answer 10

+46ATP

Theoretically 38 but 2 NADH in wrong compartment

Question 11

Brown adipose tissue

Answer 11

More rare than white
Mitochondria largely ‘uncoupled’ however some still are to make some ATP to keep the cells alive
Energy released as heat rather than captured as ATP
Important for maintaining body temp (thermoregulation)
Proton gradient dissapated: generates heat
Especially important in neonates and hibernating animals

Dinitrophenol is an uncoupler
Can carry H+ across membranes; uncouples white mitochondria