Gluconeogenesis

Question 1

Step 1a in Gluconeogenesis

Answer 1

2 Pyruvate —> 2 Oxaloacetate
- Enzymes: Pyruvate Carboxylase
- 2 HCO3- + 2 ATP —> 2 ADP + 2 Pi

Additional Info:
- Not in glycolysis

Question 2

Step 1b in Gluconeogenesis

Answer 2

2 Oxaloacetate —> 2 Malate —> 2 Oxaloacetate
- Enzyme: Malate Dehydrogenase
- NADH —> NAD+ —> NADH

Additional Info:
- Since Oxaloacetate can’t move out of the mitochondria, Malate Dehydrogenase converts it into Malate, and then back into Oxaloacetate in the cytoplasm
- Not in glycolysis

Question 3

Step 1c in Gluconeogenesis

Answer 3

2 Oxaloacetate —> 2 Phosphoenolpyruvate
- Enzyme: Posphoenolpyruvate Carboxykinase
- 2 GTP —> 2 GDP

Additional Info:
- Occurs in the cytoplasm
- Not in glycolysis

Question 4

Steps 2-7 in Gluconeogenesis

Answer 4

2 Phosphoenolpyruvate —> Fructose-1,6-Bisphosphate
- Same enzymes used in glycolysis but in reverse

Additional Info:
- Step 4 also involves 2 ATP —> 2 ADP
- Step 5 also involves 2 NADH —> 2 NAD+

Question 5

Step 8 in Gluconeogenesis

Answer 5

Fructose-1,6-Bisphosphate —> Fructose-6-Phosphate
- Enzyme: Fructose-1,6-Bisphosphatase

Additional Info:
- Occurs in the cytoplasm
- The enzyme cleaves the Pi, rather than using transfer to ADP
- Not in glycolysis

Question 6

Step 9 in Gluconeogenesis

Answer 6

Fructose-6-Phosphate —> Glucose-6-Phosphate
- Enzyme: Phosphoglucose Isomerase

Additional Info:
- Same enzyme used in step 2 of glycolysis

Question 7

Step 10 in Gluconeogenesis

Answer 7

Glucose-6-Phosphate —> Glucose
- Enzyme: Glucose-6-Phosphatase

Additional Info:
- Occurs in the rER
- The enzyme cleaves the Pi rather than using ADP
- Not in Glycolysis

Question 8

Products of Full Gluconeogenesis

Answer 8

-4 ATP
-2 GTP
-2 NADH
1 Glucose