Question

An actively respiring bacterial culture is briefly incubated with [1-14C] glucose (glucose labeled with C radioisotope at carbon 1), and the glycolytic and citric acid cycle intermediates are isolated. a. On a separate piece of paper to be turned in with your homework, draw glycolysis and one turn of the citric acid cycle using [1-14C] glucose and clearly show the 14C label in each step. b. State where the lºc label is in each of the intermediates listed below. Consider only the initial incorporation of "C, in the first pass of labeled glucose through the pathway.

i. Fructose-1,6-bisphosphate
ii. Glyceraldehyde-3-phosphate
iii. Phosphoenolpyruvate
iv. Acetyl-CoA
v. Citrate
vi. a-ketoglutarate
vii. Oxaloacetate

Answer 1

Answer:

i) C-1

ii) C-3

iii) C-3

iv) C-2 (methyl group)

v) C-4

vi) C-4

vii) Equally distributed in C-2 and C-3.

Explanation:

i) In  Fructose-1,6-bisphosphate , initial incorporation of 14^C occurs at C-1

ii) In Glyceraldehyde-3-phosphate, initial incorporation of 14^C occurs at C-3

iii) In Phosphoenolpyruvate, initial incorporation of 14^C occurs at C-3

iv) In Acetyl-CoA, initial incorporation of 14^C occurs at C-2 (methyl group)

v) In Citrate, initial incorporation of 14^C occurs at  C-4

vi) In a-ketoglutarate, initial incorporation of 14^C occurs at C-4

vii) in Oxaloacetate, initial incorporation of 14^C occurs at Equally distributed in C-2 and C-3.