TCA And Oxidative Phosphorylation Flashcards Preview

Phase 1 - S2 Metabolism, Endocrinology, Haematology > TCA And Oxidative Phosphorylation > Flashcards

Flashcards in TCA And Oxidative Phosphorylation Deck (49)
Loading flashcards...
1

What does Pyruvate Dehydrogenase do?

Catalyses the conversion of pyruvate to acetyl CoA, producing CO2 and NADH

2

Where is Pyruvate Dehydrogenase found

Mitochondrial matrix

3

Why is Pyruvate Dehydrogenase sensitivity to a vitamin B1 deficiency

The enzyme activity requires cofactors and B vitamins provide these factors

4

True or false: the reaction catalysed by pyruvate dehydrogenase is reversible

False. It's irreversible making it a key regulatory step

5

What activates pyruvate dehydrogenase

Pyruvate, CoA, NAD+, ADP and Insulin (low energy signals)

6

What inhibits Pyruvate Dehydrogenase

Acetyl CoA, NADH, ATP, citrate (high energy signals)

7

True or False: Pyruvate cannot be formed from acetyl-CoA

True, the loss of CO2 is irreversible

8

What does a deficiency in pyruvate dehydrogenase lead to

Lactic acidosis (increase in blood lactate levels)

9

Where does the TCA cycle occur

Mitochondrial matrix

10

What does TCA stand for

Tricarboxylic Acid cycle

11

Outline the Kreb's cycle

- Acetyl CoA binds with the 4 carbon oxaloacetate to form the 6 carbon citrate
- citrate is converted into the 6 carbon isocitrate
- isocitrate dehydrogenase oxidises isocitrate causing the loss of CO2 and production of NADH
- alpha-ketoglutarate is oxidised by alpha-ketoglutarate dehydrogenase causing the loss of CO2 and production of NADH
- compound is modified releasing CoA and producing GTP
- FADH2 is produced
NADH produced to reform oxaloactetate

12

For 1 molecule of glucose what is produced in the TCA cycle

6 NADH
2 FADH2
2 GTP

13

What are isocitrate dehydrogenase and alpha-ketoglutarate dehydrogenase regulated by

High energy signals (ATP and NADH)

14

True of false: alpha-ketoglutarate dehydrogenase is inhibited by its product

True

15

How does the Kreb's cycle allow for anabolic reactions

It supplies intermediates for biosynthetic processes

16

Give some example of interconversions allowed by the Kreb's cycle

- citrate to fatty acids
- alpha-ketoglutarate into amino acids
- oxaloacetate into glucose and amino acids

17

Does the Kreb's cycle occur in the absence of oxygen

No, as the NADH and FADH2 cant offload their hydrogen and so there are no free NAD+ and FAD to pick up hydrogen so the TCA stops

18

By the end of the Kreb's cycle how much ATP has been produced per glucose

4 ATP

19

Where does oxidative phosphorylation occur

Inner mitochondrial membrane

20

What happens to NADH and FADH2 in oxidative phosphorylation

They are reoxidised

21

Outline the electron transport which occurs before oxidative phosphorylation

NADH and FADH2 offload their electrons through a series of protein translocating complexes. As the electrons are transferred through the chain to oxygen they release energy which move hydrogen across the membrane

22

Energy from what allows the Hydrogen ions to pass into the intermitochondrial space

Energy is released when the electrons are transferred through the protein carrier molecules

23

Why are the electrons transferred through more than one carrier molecule in steps

So that energy is contained and you have more control on the production so less energy is wasted

24

How many hydrogen ions travel through the membrane due to 1 molecule of NADH offloading it's electron pair

6

25

How many hydrogen ions are transferred through the carrier molecules when 1 molecule of FADH2 offloads it's electron pair

4

26

Why does NADH allow to movement of more hydrogen ions

It's a higher energy molecule

27

What proportion of the energy released by the movement of electrons is used to pump hydrogen ions across the membrane

30% the rest is lost as heat

28

Why is a hydrogen ion gradient allowed to build up

The inner mitochondrial membrane is very impermeable so hydrogen ions can move through easily, they had to move through the carrier molecules

29

What is the proton motive force

The hydrogen ion gradient across the inner mitochondrial membrane

30

What does ATP synthase catalyse

The production of ATP from ADP + Pi as hydrogen ions flow through the enzymes down their electrochemical gradient