Determine fraction of the molecules

1. If C-1 of glucose is radioactively labeled and then enters glycolysis, which carbon of G-3-P will be labeled? What fraction of the molecules will carry the radioactive label?

2. 14-CO2 was bubbled through a suspension of liver cells that was undergoing gluconeogenesis from lactate to glucose. Which carbons in the glucose molecule synthesized would become radioactive?

3. (A) In the anaerobic oxidation of glucose to ethanol, which carbon or carbons of glucose would be most rapidly lost as CO2? (B) Conversely, under aerobic conditions pyruvate can be decarboxylated to yield acetyl CoA and CO2. Which carbons of glucose must be labeled with 14C to yield 14CO2?

4. Would 32Pi (radio-labelled phosphate) be incorporated into any glycolytic intermediate or pathway product

5. Pyruvate and ATP are end products of glycolysis. In active muscle cells, pyruvate is converted to lactate and excreted into the blood stream. Lactate is transported to the liver where it is recycled by gluconeogenesis to glucose. The glucose can then be transported back to the muscle for aIDitional ATP synthesis. Why don’t active muscle cells export pyruvate to the liver since it too can be converted to glucose by gluconeogenesis?

6. Indicate for the following statements about gluconeogenesis whether they are true or false (T or F).
A. ____ It occurs completely in the mitochondrial matrix.
B. ____ Pyruvate carboxylase if the first enzyme in the pathway.
C. ____ Precursors of glucose include lactate, pyruvate, glycerol and alanine.
D. ____ Only three reactions are needed to bypass the irreversible steps of glycolysis.
E. ____ Some reactions occur in the mitochondrial matrix and some in the cytoplasm.

7. What would be the effect in an individual in whom the enzyme triose phosphate isomerase (TPI) was either deficient or inhibited?

8. Calculate the number of “net ATP” molecules obtained the anaerobic conversion of each of the following sugars to lactate.
(a) Glucose.
(b) Fructose.
(c) Mannose.
(d) Sucrose.

9. What is the ATP yield for the oxidation of one glucose molecule? (a) “Net ATP” after glycolysis and TCA, but not the electron transport chain. (b) “Complete oxidation” going through everything

10. Complete oxidation of glyceraldehyde-3-phosphate (G-3-P) would net how many ATP equivalents?