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SURVEY OF BIOCHEMISTRY
More on Glycogen Control
Citric Acid Cycle
1
Agenda
• Recap regulation of glycogen metabolism
• What we have covered
–
–
–
–
Glycolysis
Glycogen breakdown
Glycogen synthesis
Gluconeogenesis
• Citric Acid Cycle overview
2
Ways to Regulate Glycogen
Metabolism
• Allosteric Control
• Covalent Modifications
– Phosphorylation
– Dephosphorylation
Review these
for Exam #3 and
the Final Exam
• Hormonal Control
– Insulin
– Glucagon
3
Covalent Modifications
Glycogen Phosphorylase
cAMP activates PKA
Glucagon stimulates
this process
Glycogen
phosphorylase
participates in
glycogen
breakdown
4
Hormonal Control
Insulin
Glucagon
Secreted in the beta cells
Secreted in the alpha cells
51 aa peptide hormone
29 aa peptide hormone
Increases glycogen synthesis
Increases glycogen breakdown
Decrease blood glucose
Increases blood glucose
Increases cellular uptake of
glucose to make glycogen
5
Hormonal Control
6
Amino Acid Entry Into TCA Cycle
Notice how there are
different pathways
for aa’s to enter into
the TCA cycle.
7
Citric Acid
Cycle
Overview
Alternative Names for
Cycle:
Kreb’s Cycle
Tricarboxylic Acid
(TCA) Cycle
8
Fates of Pyruvate
Focus on pyruvate entry into the TCA cycle.
Pyruvate
Amino
Acids
Acetyl-CoA
Citric Acid
Cycle
Fatty
Acids
Key Products
CO2
NADH
FADH2
GTP
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