Carbohydrate metabolism 2 Flashcards
Overview of glucose oxidation
1) glucose
2) glucose-6P
3) triose-P
4) pyruvate
5) lactate
Which is the only reversible reaction in glucose oxidation
Pyruvate to lactate
Where does glycolysis occur
Cytosol
Where does oxidation occur
Mitochondrial matrix
What happens to pyruvate in oxidation
- can become lactate
- Goes to become acetylcoa which feeds into the TCA cycle
What is the purpose of the TCA cycle
Energy production
What does the TCA cycle prduce
- removal of pairs of electrons to form NADH and H+ and FADH2 from NAD+ AND FAD+
- biosynthesis of metabolites
What does pyruvate dehydrogenase do
Turn pyruvate into acetyl CoA
Reaction of pyruvate to acetyl CoA
Pyruvate + NAD+ + CoA—>
Acetyl CoA+ NADH +CO2
Why is the pyruvate dehydrogenase reaction important
- commits pyruvate to TCA cycle
- Controls the entry of glucose to TCA cycle
- RATE LIMITING STEP
- irreversible
- regulated
How is the pyruvate dehydrogenase reaction regulated
- allosterically
- covalently
- hormonally (insulin activates)
How many enzyme activities are there of PDH
3
What are the enzyme activities of PDH
E1
E2
E3
5 coenzymes of PDH
Thiamine LIpoamine CoA FAD+ NAD+
what is the inactive form of PDH
PHosphprylated
What is the active form of PDH
Dephosphorylated
How is PDH turned from inactive to active
Phosphatase
What is phosphatase activated by
Insulin an Ca2+
HOw is PDH turned from active to inactive
Kinase
How Is kinase activated
ATP
NADH
AcetylCoA
Products of the TCA cycle (for each molecule of Acetyl CoA)
2x Co2 FADH2 3x NADH CoA GTP
IN the TCA cycle, what turns isocitrate (5c) into alpha-ketoglutarate
Isocitrate dehydrogenase
What is isocitrate dehydrogenase inhibited by
ATP and NADH
What is osicitrate dehydrogenase activated by
adp
