Question

1. If the C-1 carbon of glucose were labelled with 14C, which of the carbon atoms in pyruvate would be labelled after glycolysis?

a) the carboxylate carbon

b) the carbonyl carbon

c) the methyl carbon

*** the Answer is c) but I don't understand why, can u plz explain why?

2. How many "high energy" bonds are required to convert oxaloacetate to glucose?

***answer is 4 but I don't understand why, can u plz exapain

3. Which of the following statements correctly describes what happens whe acetyl CoA is abundant

a) Pyruvate carboxylase is activated

b) phosphoenolpyruvate carboxykinase is activated

c) phosphofructokinase is activated

d) If ATP levels are high, oxaloacetate is diverted to gluconeogenesis

e) If ATP levels are low, oxaloacetate is diverted to gluconeogenesis

*** Answer is a) and d), can u plz explain why thank you!

Last question, can liver cells do glycolysis, or do they only do gluconeogenesis?

Answer 1

1) you will. Get radioisotopes on methyl carbon because other carbons of glucose becomes modified and half is broken down into dihydroxyacetone phosphate and glyceraldehyde 3 phosphate .

And the 1 C of glucose become CH3 after various reduction step.

That why methyl carbon of pyruvate remain radiolaveled.

2)first oxaloacetate is transported out of MITOCHONDRIA but it has to converted to malate using NADH by reduction because oxaloacetate can't cross mitochondrial membrane .

Then, malate again converted to oxaloacetate using NAD+.

THEN, OXALOACETATE IS CONVERTED to PHOSHOENOLPYRUVATE using one high energy molecule, GTP.

Then, phosphoenolpyruvate converted into 2 phosphoglycerate and 3 phosphoglycerate next, one ATP is need to make 3 phosphoglycerate to 1,3 bisphophoglycerate and then phosphoglycerate then converted into GLYCERALDEHYDE 3 phosphate using NADH2 AND ONE PHOSPHATE IS RELEASED.

Them, aldolase add then dihydroxyacetone phosphate and G3P to fructose 1,6 bis PHOSPHATE.

Then, one phosphate is released and Fructose 1,6 bisphosohate becomes fructose 6 phosphate and

And fructose is converted to glucose 6 phosphate and which is become glucose by releasing phosphate.

So, there is two direct use of high energy bond, but one direct involved of NADH which also gives 2.5 molecules of ATP , so .net 4.5 or 5 high energy bonds is required.

3) pyruvate carboxylase is activated and when ATP is high then, oxaloacetate is diverted to gluconeogenesis because when acetyl co A is in huge amount and ATP is also high then,because pyruvate carboxylase converts pyruvate to oxaloacetate 2hich then produce glucose .

Liver cell perform both GLYCOLYSIS and gluconeogenesis because it has also need of energy that why glucose is converted and giver energy.