Question

ATP labeled with 32P a radioactive isotope of phosphorus at the gamma phosphate is added to a crude extract of a tissue rich in the enzymes of glycolysis along with glucose. What is the first intermediate of glycolysis that will no longer be radioactive?

Answer 1

Piruvate

Step-by-step explanation:

Glucose + ATP32 --------> Glucose-6-P32 ----->Fructose-6-P32

Fructose-6-P32 + ATP32 ---------> Fructose-1,6 bi-P32

Fructose-1,6 bi-P32 ----------> Glyceraldehyde-3-P32 + Dihydroxiacetone Phosphate32 (that are in equilibrium)

Glyceraldehyde-3-P32 +NADH +Pi (non radioactive) -----> Glyceraldehyde-1,3-P32 (1,3 biphosphoglycerate where only in C3, there is a P32)

After that, the phosphorus in Carbon1 is donated to ADP to for ATP (non radioactive), and we have 3-Phosphoglycerate (radioactive because its P32), then it's converted to 2-Phosphoglycerate (radioactive), then Phosphoenolpiruvate (radioactive), that donates its P32 to ADP to produce ATP, remaining Piruvate as end product at the end of glucolysis