Chapter 13 ( Citric Acid Cycle And Oxidative Phosphorylation ) Flashcards Preview

Biochemistry ahmed > Chapter 13 ( Citric Acid Cycle And Oxidative Phosphorylation ) > Flashcards

Flashcards in Chapter 13 ( Citric Acid Cycle And Oxidative Phosphorylation ) Deck (18)
Loading flashcards...
1
Q

Krebs cycle general formula ?

A

Acetyl-CoA ( 3NAD + FAD + GDP + Pi ) ———-> 2 CO2 ( 3NADH + FADH2 + GTP )

2
Q

Location of the enzymes in citric acid cycle ?

A

All of them are in the matrix of mitochondria except succinate dehydrogenase which is in the inner membrane

3
Q

Oxidation of what fuels that yield Acetyl-CoA ?

A
Glucose 
Fatty acids 
Keton bodies 
Ketogenic amino acids 
Alcohol
4
Q

What is the major control enzyme of citric acid cycle ? Its activators and inhibitors ?

A

Isocitrate dehydrogenase
Activated by NADH and ATP
Inhibited by ADP

5
Q

Intermediates of Krebs cycle that serve other functions ?

A

Citrate : may leave the mitochondria to deliver acetyl-CoA into the cytoplasm for fatty acid synthesis
Succinyl-CoA : high energy intermediate that can be used for heme synthesis and to activate Kenton bodies in extra hepatic tissue
Malate : can leave the mitochondria for gluconeogenesis

6
Q

Enzyme that function both in Krebs cycle and electron transport chain ?

A

Succinate dehydrogenase ( present in the inner membrane of mitochondria )

7
Q

Inhibitors of NADH dehydrogenase ( complex l ) in ETC ?

A
Barbiturates 
Rotenone ( an insecticide )
8
Q

Components of the wire in electron transport chain ?

A
NADH dehydrogenase ( complex l )
Coenzyme Q
Cytochrome b/c1 ( complex lll )
Cytochrome C
Cytochrome a/a3 ( complex lV )
9
Q

Proton translocators in ETC ?

A

Complex l , lll , lV

10
Q

Describe oxidative phosphorylation ?

A

As protons flow into the mitochondria through the F0 component of ATP synthase as a result of ETC , their energy is used by the F1 component of ATP synthase to phosphorylate ADP into ATP using Pi

11
Q

Cyanide : Sources ? Mechanism ? Antidotes ?

A

Sources :
Burning polyurethane ( foam stuffing in furniture and mattress )
Byproduct of nitroprusside
Mechanism : binds irreversibly to Cytochrome a/a3 ( complex lV ) in ETC preventing electron transfer to oxygen and producing changes like tissue hypoxia
Antidotes:
Nitrites ( convert Hb to met-Hb which binds cyanide in the blood before reaching the tissues )
Na thiosulphate ( converts cyanide to thiocyanate which is less toxic )
Vitamin B12 ( binds to cyanide

12
Q

Carbon monoxide : sources ? Mechanism ? Antidote ?

A

Sources : propane heaters , gas grills , vehicle exhaust , house fire , smoking , methylene chloride based paint strippers
Mechanism : binds to cytochrome a/a3 also binds to Hb displacing oxygen
Antidote : Hyperbaric oxygen

13
Q

Inhibitor of cytochrome b/c1 ?

A

Antimycin

14
Q

Inhibitor of Coenzyme Q ?

A

Doxorubicin

15
Q

Inhibitor of the F0 component of ATP synthase ?

A

Oligomycin

16
Q

Examples for synthetic and natural Uncouplers of ETC ?

A
Synthetic : 
2,4-dinitrophenol
Aspirin 
Natural : 
UCP ( thermogenin )
17
Q

The enzyme responsible for substrate level phosphorylation in Krebs cycle ?

A

Succinyl-CoA synthetase

18
Q

Dehydrogenases of Krebs cycle ?

A

1- Isocitrate dehydrogenase (NAD)
2- Alpha-ketoglutarate dehydrogenase (NAD)
3-Succinate dehydrogenase (FAD)
4-Malate dehydrogenase (NAD)