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Gluconeogenesis
- A method of replenishing blood glucose
- Occurs in the liver and kidneys
- Converts lactate and pyruvate back to glucose
- 3 steps are different from glycolysis (4 enzymes)
- Net equation:
- Pyruvate + ATP + GTP + NADH + H2O + 2 H+ --> Glucose + ADP + GDP + NAD+ + Pi
https://en.wikipedia.org/wiki/File:Glycolytic_and_gluconeogenic_pathways.jpg. Dwong527. Creative Commons Attribution-Share Alike 3.0 Unported license.
Glycerol
- Glycerol is released into the blood stream from fat mobilization
- Enters gluconeogenesis as DHAP
- This requires 2 enzymes:
- Glycerol kinase: requires ATP
- Glycerol phosphate dehydrogenase: makes NADH
- Net equation:
- Glycerol + ATP + NAD+ + H2O --> Glucose + ADP + Pi + NADH
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Regulation of Gluconeogenesis
- Reciprocal regulation promotes either glycolysis or gluconeogenesis
- This occurs via hormone signalling
- Regulation of pyruvate <--> phosphoenolpyruvate
- Activates pyruvate kinase: AMP, F-1,6-BP
- Inhibits pyruvate kinase: ATP, acetyl-CoA, alanine
- Activates pyruvate carboxylase: acetyl-CoA
- Inhibits pyruvate carboxylase and phosphophoenolpyruvate carboxykinase: ADP
- Regulation of fructose 1,6-bisphosphate <--> fructose 6-phosphate
- Activates phosphofuctokinase-1: F-2,6-BP, AMP
- Inhibits phosphofuctokinase-1: ATP, citrate
- Activates fructose-1,6-bisphosphatase (FBPase): citrate
- Inhibits fructose-1,6-bisphosphatase: F-2,6-BP, AMP
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Which of these molecules activate pyruvate kinase?
a. Alanine
b. AMP
c. Acetyl-CoA
d. ATP
b. AMP
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Which statement is FALSE about Gluconeogenesis?
a. It occurs in the liver and kidneys
b. It replenishes blood glucose levels
c. There are four enzymes involved in gluconeogenesis that are not found in glycolysis
d. It converts lactate and pyruvate back to glucose
e. None of the above
e. None of the above
What are the three steps that differ between glycolysis and gluconeogenesis?