09 Fructose And Galactose
Absorption

monosaccharides

Fructose

table sugar
fructose can be metabolized and feed into glycolysis

fructokinase add phosphate from ATP
aldolase B splits F1P to 2 3C molecules

fructose enter pathway beyond rate limiting step, faster than either glucose/galactose

hexokinase can convert fructose to F6P (step 2)
Essential Fructosuria

Hereditary Fructose Intolerance


no aldolase
fructose continuously converted to F1P, using up ATP

need ATP for gluconeogenesis and glycogen breakdown

no fructose from breast milk
wean from breast milk, start fructose
Polyol

sorbitol converted to fructose

diabetes locaitons

Galactose

G1P intermediate in glycogen synthesis, can be used for glycogen synthesis or converted to G6P

Classic Galactosemia

GALT
G1P builds up in liver and leads to liver damage, also deplete ATP supply

also causes cataracts

galactose in milk

Galactokinase Deficiency

Galactose not converted to G1P, milder symptoms, no depletion of phosphate and no trapping in liver
young child with vision problems
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