Title: Carbohydrate processing gluconeogenesis pentose phospate pathway
1Carbohydrate processing gluconeogenesis
pentose phospate pathway
S 2006 BIOC 3406 1-31-2006
2Fates of ingested polysaccharides
- Glycogen or starch H2O ? oligosaccharides,
dextrins, di- and trisaccharides - Dextrin n H2O ? n D-glucose (brush border)
- Maltose H2O ? 2 D-glucose
- Lactose H2O ? D-glucose D-galactose
- Sucrose H2O ? D-glucose D-fructose
- Trehalose H2O ? 2 D-glucose
mouth, upper GI
brush border
3Course of digestion
- a-amylase breaks down glycogen/starch
- salivary, pancreatic
- Brush border enzymes break di- and
tri-saccharides down to monosaccharides for
absorption
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7Mistake in your book
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12Galactokinase Deficiency Galactosemia
(This would be a CHO in galactose)
Galactokinase deficiency leads to high galactose
concentrations and the presence of galactitol,
which causes cataracts
13Other galactosemias
- Transferase deficiency
- More serious than GKD Galactosemia
- Poor growth
- Speech problems
- Mental retardation
- Liver damage
- Epimerase deficiency
- Similar to transferase deficiency but less severe
with control of galactose intake
14Anaerobic fates of pyruvate
- Tied to fate of NADH formed in glycolysis
- O2 should be acceptor of NADHs reducing
equivalent, but if it is not - Pyruvate is fermented and NADH ? NAD H
- Lactic acid fermentation
- Ethanol fermentation
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20This is resonance but is shown incorrectly. The
two forms do not have different structures
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22Pyruvate ATP GTP HCO3- ? PEP ADP GDP
Pi CO2
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24(This amounts to feedback inhibition)
AcSCoA
Note addition of CO2
25Followed by loss of CO2
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28In the cytosol, NAD/NADH is high, but in
mitochondria NAD/NADH is low.
In cytosol
Important in large mammals (you)
29Note how much it costs to convert pyruvate to
glucose!
30Other paths to glucose
- Citric acid cycle intermediates
- Amino acids
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32Pentose phosphate pathway
- Various names
- Pentose pathway
- Phosphogluconate pathway
- Hexose monophosphate pathway
- Oxidative Part
- Produces pentoses, NADPH
- Nonoxidative
- Balances 5,6-ose phosphates
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39Nonoxidative phase
- Reshuffling of pentoses to hexoses
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