Green - Gluconeogenesis

Question 1

Location of Glycolysis and Gluconeogenesis?

Answer 1

Glycolysis: Muscle/Brain

Gluconeogenesis: Liver (90)/Kidney (10)

Question 2

Three Irreversible (bypass) steps of Glycolysis?

Answer 2

Glucose to G6P by hexokinase

Phosphorylation of F6P to F1,6BP by PFK-1

Conversion of PEP to pyruvate by Pyruvate Kinase

Question 3

Enzyme for Pyruvate to Oxaloacetate?

Regulation?

Answer 3

Pyruvate Carboxylase

(+) Acety-CoA allosteric activator

Requires Bicarbonate, Biotin, ATP

Question 4

What can pyruvate be converted to?

Answer 4

Acetyl CoA (Citric Acid Cycle)

Oxaloacetate (Gluconeogenesis)

Question 5

How must oxaloacetate be transported by mitochondria?

Answer 5

Must be converted to malate in both in/out directions; can’t move oxaloacetate across membrane

Question 6

Acetyl CoA regulation of gluconeogenesis

Answer 6

Acetyl CoA High = (-) Pyruvate Dehydrogenase, which catalyzes its creation (negative feedback)

Acetyl CoA Low = (+) Pyruvate carboxylase, which catalyzes creation of Oxaloacetate

Question 7

Regulation of Oxaloacetate to PEP

Answer 7

• Requires GTP
• Key enzyme = PEPCK (PEP Carboxykinase)

(+) Glucagon Activates

(-) Insulin Inhibits

Question 8

Regulation of Fructose 1,6 Bisphosphate to Fructose 6-phosphate by fructose 1,6-bisphosphatase-1 (FBPase-1)

Answer 8

(+) Citrate

(+) ATP

(-) AMP

(-) ADP

Question 9

Citrate role in regulation?

Answer 9

Key intermediate in aerobic oxidation of pyruvate, fatty acids, and amino acids–when high = cell meeting energy needs

Question 10

Fructose 2,6 Bisphosphate–targets for regulation?

How is IT regulated?

Answer 10

(+) PFK-1

(-) FBPase-1

• Both of these combined push to glycolysis

- - -

(+) Glucose = Activation

(+) Insulin = Activation

(-) Glucagon

Question 11

G6P to Glucose

Answer 11

Catalyzed by glucose-6-phosphatase

Enzyme located in ER of liver and kidney

Question 12

Lactate as a substrate for gluconeogenesis

Answer 12

Pyruvate generated from lactate; important for skeletal muscle–converted to oxaloacetate

Question 13

Glucogenic Amino Acids as substrate for gluconeogenesis

Answer 13

Amino Acids deaminated

Carbon skeletons can enter Citric Acid Cycle

Forms PEP, can enter gluconeogenesis pathways

Question 14

Fats as substrates for gluconeogenesis?

Answer 14

Glycerol phosphorylated by glycerol kinase, can enter pathway

***Triglycerides can’t enter direction, have to be cut down to backbone first

Question 15

Cori Cycle

Answer 15

Lactate generated by glycolysis transported to liver

In liver, lactate converted to glucose

Glucose transported back to muscle to be used as fuel

Question 16

What are three major sources for gluconeogenesis?

Answer 16

Glucogenic Amino Acids, Lactate, Glycerol