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SURVEY OF BIOCHEMISTRY

More on Glycogen ControlCitric Acid Cycle

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Agenda

• Recap regulation of glycogen metabolism

• What we have covered – Glycolysis– Glycogen breakdown– Glycogen synthesis– Gluconeogenesis

• Citric Acid Cycle overview

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Ways to Regulate Glycogen Metabolism

• Allosteric Control

• Covalent Modifications– Phosphorylation– Dephosphorylation

• Hormonal Control– Insulin– Glucagon

Review thesefor Exam #3 and the Final Exam

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Covalent ModificationsGlycogen Phosphorylase

Glycogen phosphorylaseparticipates in

glycogen breakdown

Glucagon stimulatesthis process

cAMP activates PKA

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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

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Hormonal Control

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Amino Acid Entry Into TCA Cycle

Notice how there aredifferent pathways

for aa’s to enter intothe TCA cycle.

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Citric Acid Cycle

Overview

Alternative Names for Cycle:

Kreb’s Cycle

Tricarboxylic Acid (TCA) Cycle

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Fates of Pyruvate

Focus on pyruvate entry into the TCA cycle.

Pyruvate

Acetyl-CoAAmino Acids

Fatty Acids

Citric AcidCycle

Key ProductsCO2

NADHFADH2

GTP