Quiz

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Quiz

• Cells generally have at most 2 G protein type
  receptors but can have multiple RTK types
• Why?

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Talk Schedule Talks are 15 min1 min 5-10 min
questions
1.3X10-15
1.3X10-15

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Where we are at

• Finished Signal Transduction
• At Bat Global Regulation
• Exam Friday due following Friday? or combined
  exam for final?
• On Deck?
• Student talks

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Problems

• Problems Chapt, 121, 2, 6, 7, 11,
• chapt. 19 Problems 1, 2, 3, 10
• Chapt 20 Problems 1, 6, 8, 9, 10
• Problems chapt 26 1, 2, 3, 4, 5, 7,9, 10, 13
• Problems Chapt 27 1, 3, 4, 6,

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Structures you should have memorized
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Page 550
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Pathways we have talked about

• Glycolysis
• Gluconeogenisis
• Glycogen synthesis
• TCA cycle
• Electron transport

• Fatty acid synthesis
• Fatty acid degradation
• Amino acid synthesis
• Amino Acid degradation

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Figure 27-1 The major energy metabolism pathways.
Page 1055
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Figure 27-2 The metabolic interrelationships
among brain, adipose tissue, muscle, liver, and
kidney.
Page 1057
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Control of Glycogen Synthesis and Breakdown

• Need to have glucose available at constant
  concentrations ( 5 mM) for the brain, as well as
  for muscle contraction.
• Homeostasis achieved by control of glycogen
  phosphorylase and glycogen synthase
• Phosphorylase is controlled allosterically and by
  covalent modification phosphorylation
• Synthase is also controlled by phosphorylation
• The critical role of hormones insulin and glucagon

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Phosphorylase is also controlled by
phosphorylation

• Early work showed that Gly. Phos. existed in an
  a and b forms
• Subsequently learned that a and b differed by
  phosphorylation at Ser 14
• Phosphorylated form is allosterically
  unresponsive and turned on! The apo enzyme is
  still allosterically regulated
• Controlled by a hormone driven cascade

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Hormonal Control of Glycogen Synthesis and
Degradation

• Many hormones control blood glucose
  concentration insulin, glucagon, epinephrine,
  and glucocorticoids
• Insulin stimulates glycogen synthesis, inhibits
  glycogen breakdown (liver, muscle)
• Glycogen breakdown triggered by epinephrine
  (liver, muscle), glucagon (liver, adipose).
  Different signals for each.

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Regulatory cascades control glycogen synthesis
and mobilization

• Both phosphorylase and glycogen synthase can
  exist in PO4/non-PO4 forms
• The activity of these enzymes is controlled
  inversely
• G-6-P is a key allosteric regulatory molecule

Phosphorlyl.
Synthase.
Phosphorlyl.
Synthase.
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Pentose Pathway

• Critical product levels
• NADPH and Ribose
• NADPH needed Pathway runs forward excess funneled
  into Glycol sis, Gluconeogenisis or Glycogen
  Synthesis.
• if both are needed Pathway stops at NADPH and
  Ribose
• Ribose needed Pathway runs backwards to Ribose

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Fatty acid Regulation

• Primarily at AcetylCoA Carboxylase
• First committed step in synthetic pathway
• Citrate activates AcetylCoA carboxylase
• Palmitate inhibits AcetylCoACarboxylase
• Malonyl CoA inhibits mitochondrial transport of
  FACoA
• cAMP dependent phosphorylation inhibits
  AcetylCoACarboxylase and activates lipase in
  adipocytes.
• Insulin dependent dephosphorylation activates
  enzyme

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Amino Acid Regulation

• Over all regulated at the synthisis of Glutamine
  synthatase.
• controls amount of Glutamine
• Controls amount of Glutamate
• Substrate for Transferases
• Individual synthetic pathways regulated by feed
  back inhibition of either first committed step or
  regulation of the gene product in the pathway.

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Degradation of amino acids to one of seven common
metabolic intermediates.
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