Term
| where is fructose found in the diet |
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Definition
| sucrose, fruit, table sugar |
|
|
Term
| how is fructose taken into the cell, how does this affect the chemical messengers in metabolism |
|
Definition
| by non-insuliin dependent transporters, does not promote insulin secretion |
|
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Term
| what is the first (common) step in fructose metabolism |
|
Definition
| fructose to fructose-1-phosphate using ATP vua fructokinase |
|
|
Term
| where is fructokinase located |
|
Definition
| mostly in the liver, kidney, small intestine mucosal cells |
|
|
Term
| what is the first (uncommon) step in fructose metabolism. why is it uncommon |
|
Definition
| fructose to fructose-6-phosphate vua hexokinase. because hexokinase has a low affinity so you would need a lot of fructose |
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|
Term
| what is fructose-1-phosphate turned into, by what |
|
Definition
| DHAP and glyceraldehyde by aldolase B |
|
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Term
| what pathways can aldolase B be part of, why is it special |
|
Definition
| it can be part of glycolysis or fructose metabolism, but none of the other aldolases that can take part in glycolysys can do fructose metabolism. |
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|
Term
| in fructose metabolism, what happens to glyceraldehyde |
|
Definition
| it is turned into glycerol. turned into glyceraldehyde-3-P and used for glycolysis or gluconeogenesis |
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|
Term
| what happens to DHAP in fructose metabolism |
|
Definition
| it is used for glycolysis or glyconeogenesis |
|
|
Term
| why is fructose rapidly metabolized |
|
Definition
| because it skips the PFK-1 step in its metabolism, it is not regulated like glycolysis is |
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Term
| what turns glucose into sorbitol |
|
Definition
|
|
Term
| what turns sorbitol into fructose |
|
Definition
|
|
Term
| where is aldose reductase located |
|
Definition
| lens, retina, schwann cells of peripherial nerves, liver, kidney, cells of ovaries, seminal vesicles |
|
|
Term
| where is sorbitol located |
|
Definition
| liver, kidney, ovaries, seminal vesicles |
|
|
Term
| what happens in an sorbitol dehydrogenase deficiency |
|
Definition
| glucose turns into sorbitol and it builds up making osmotic water uptake causing diabetes symptoms: cataracts, retinopathy, neuropathy |
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|
Term
| what can cause glucose to turn into sorbitol |
|
Definition
| some tissues require the product of the next step, fructose. if there is a lot of glucos ein the blood this will just happen |
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|
Term
| what is the name of the disease with a fructosekinase deficiency |
|
Definition
| essential fructoseuira / HFI |
|
|
Term
| what does a fructose kinase deficiency cause |
|
Definition
| elevated sugar levels in urine, benign |
|
|
Term
| why is cataracts not a symptom of fructose kinase deficiency |
|
Definition
| because fructose is not a substrate for aldolase reactions |
|
|
Term
| what does aldolase B deficiency cause |
|
Definition
| fructose intolerance, hepatomeaguly, jaundice, hypoglycemia, renal dysfunction |
|
|
Term
| how is aldolase b deficiency treated |
|
Definition
| avoid fructose, sucrose, and sorbitol |
|
|
Term
| what are the steps in an aldolase b deficiency causing hyperuricema |
|
Definition
| fructose enters the cell and is phosphorlyated trapping it in, it cannot be metabolized so it builds up, cellular phosphate is tied up trying to phosphorlyate fructose decreasing ATP levels, AMP builds up causing AMP degeneration leading to hyperuricema |
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|
Term
| what is the first step in galactose metabolism |
|
Definition
| galactose to galactose-1-phosohate using galactose kinase and ATP. |
|
|
Term
| what does galactose-1-phosphate turn into, using what enzyme |
|
Definition
| galactose-1-phoshpate uridyltransverase helps it chane to UDP galactose and glucose-1-phosphate (using a UDP glucose made by the cell and exchanging UDP for P) |
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|
Term
| what are the symptoms of a galactokinase deficiency |
|
Definition
|
|
Term
| how does a galactokinase deficiency cause cataracts |
|
Definition
| galactose is a substrate for aldose reductase so when it builds up it reacts with that as a catalyst to make galactiol which is trapped in the cell and causes an osmotic gradient |
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|
Term
| what disease does a galactose-1-phosphate uritotransferase deficiency cause |
|
Definition
|
|
Term
| what are the symptoms of classic galactosemia |
|
Definition
| early cataracts, liver and kidney damage, nerve damage (retardation) |
|
|
Term
| what chemical process causes the symptom of cataracts in classic galactosemia |
|
Definition
| increased galactose-1-phosphate inhibits galactokinase which increases galactose causing cataracts |
|
|
Term
| what chemical process causes the symptoms of classic galactosemia |
|
Definition
| increased galactose-1-phosphate ties up the use of the cell phosphate causing decreased ATP |
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|
Term
| how is classic galactosemia treated |
|
Definition
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