Gluconeogenisis

Question 1

Describe: Gluconeogenesis

Answer 1

• Synth. of Glucose
• Brain, skeletal muscle, kidney medulla, erythrocytes, and testes use glucose as their sole or primary energy source, but they lack the enzymatic machinery to synthesize it.
• Synthesis of glucose from noncarbohydrate precursors is essential for maintenance of blood glucose levels at stable homeostatic levels (~ 5 mM).

Question 2

What are the primary gluconeogenic tissues?

Answer 2

​Liver and kidney cortex are the primary gluconeogenic tissues.

Question 3

Common precursors for Gluconeogenesis?

Answer 3

Question 4

What Amino Acids can’t be used in Gluconeogenesis?

Answer 4

Leucine and Lysine

Question 5

Metabolites that can be used byanimals for net synthesis of glucose?

Answer 5

(AcSCoA is not on this list…so,animals cannot use fatty acids to meet the metabolic demand for glucose)

Question 6

Glycolysis and gluconeogenesis differ at which steps?

Answer 6

Question 7

Why do Glycolysis and gluconeogenesis differ at certain steps?

Answer 7

Allows both glycolysis andgluconeogenesis to be thermodynamically favorable.

Question 8

Describe Gluconeogenesis “Step 1”: Pyruvate carboxylase

Answer 8

Pyruvate carboxylase is located in the mitochondrion, and catalyzes the ATP- and biotin-dependent conversion ofpyruvate to oxaloacetate.

• The enzyme requires acetyl-CoA as an allosteric activator:

The HCO3

• equivalent is delivered in a biotin-dependent process.

Question 9

Draw R and P: Pyruvate carboxylase rxn

Answer 9

Question 10

Draw R and P: Phosphoenolpyruvate carboxykinase rxn

Answer 10

Question 11

The PEPCK mechanism is an example of C-C bondcleavage using an ______________.

Answer 11

Question 12

Pyruvate carboxylaseresides in the_____________;whereas, the rest of thepathway is in the __________.

Answer 12

Pyruvate carboxylaseresides in the mitochondrial matrix; whereas, the rest of the pathway is in the cytosol.

Question 13

Shuttling of metabolites across the inner mitochondrial membrane (IMM) results in generation of______________.

Answer 13

Shuttling of metabolites across the inner mitochondrial membrane (IMM) results in generation of cytosolic NADH…

Question 14

What happens in the Gluconeogenesis “Steps 9 & 11”?

Answer 14

The phosphatase reactions are simply in-line transfer of the phosphoryl group to H2O.

Question 15

The synthesis of one glucose via gluconeogenesis requires ___ C3 (or C4) precursors

Answer 15

2

Question 16

Define: Cori Cycle

Answer 16

The “Cori Cycle” is part of the processof recovery from strenuous exertion (i.e.,lactate production in muscles). This process aids recovery from “O2 debt”.

Question 17

What is the The “Pasteur Effect”?

Answer 17

• The Pasteur effect is an inhibiting effect of oxygen on the fermentation process
• suggests interplay between complementary pathways (and their reciprocal regulation
• Explained by differences in ATP yields for aerobic vs.anaerobic glycolysis

Question 18

Metastatic tumors tend tobe _____ thus, ______ is ______ in these tumors.

Answer 18

Metastatic tumors tend to be hypoxic (due to a poor blood supply); thus, glycolysis is upregulated in these tumors