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14 Cards in this Set
- Front
- Back
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fructose metabolism |
tructokinase traps fructose as fructose 1=phosphate (liver, kidney, intestine); fructose channeled into glycolysis (to pyruvate); gluconeogenesis after fructose feeding is illogical; normal regulation by PFK is bypassed; there are 2 aldolases in this that are unique to the liver |
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essential fructosuria |
fructokinase deficiency; no clinical presentation just elevated blood and urine fructose; blood tests for fructose find reducing sugars are high and glucose oxidase is low |
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hereditary fructose intolerance |
aldolase B deficiency so fructose-1P builds up (hepatotoxic); nausea, cirrhosis, and hypoglycemia; limit fructose in diet (pt develops an aversion anyway) |
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galactose metabolism |
galactose is channeled into glucose 1-P and in turn converted to G6P (glycolytic pathway) which can go into glycolysis or gluconeogenesis; a galactokinase is used in this pathway; GALT is a transferase that puts glucose on the 1-P and gets rid of the galactose on UDP (so this forms glucose 1-P and UDP-galactose) |
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classical galactosemia |
deficiency in transferase enzyme (GALT); build up of galactose-1P is toxic (just like fructose-1P); nausea, avoidance of feeding, mental retardation, cataracts (due to elevated galactitol in lens which makes proteins precipitate out); galactitol produced by polyol pathway which also produces cataracts in diabetes from sorbitol which comes from glucose |
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galactosemia from galactokinase deficiency |
elevated blood galactose; clinical presentation limited to cataracts |
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pentose phosphate pathway |
metabolic role- supplies NADPH and ribose 5-phosphate and is present in all cells; regulation- G6P is regulated by NADP+ concentration (NADP+/NADPH=1/70 thus NADP+ is limiting); important enzymes- glucose 6P dehydrogenase (G6PD) cases NADPH production, transketolase requires thiamine PP (pyrophosphate which is an activated form of thiamine) |
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pentose phosphate pathway flexible output- branch utilized= oxidative branch only then output is |
ribose (remember that this makes ribose) plus NADPH (remember that this makes deoxyribose) DNA |
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pentose phosphate pathway flexible output- branch utilized is oxidative branch plus non oxidative branch then output is |
NADPH only (5C recycled through glycolysis) and the ribose is pushed through the pathways to fatty acid synthesis fatty acids |
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pentose phosphate pathway flexible output- branch utilized is non oxidative branch only then the output is |
ribose only RNA |
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Glutathione as an antioxidant |
aka GSH; has a free thiol on it which pulls in and reacts with free radicals; reduced form of glutathione serves as an antioxidant (neutralizes free radicals (from electron transport); glutathione peroxides uses free radicals to oxidize glutathione to GSSG (disulfides stabilize proteins in the unstable extracellular environment); glutathione reductase regenerates reduced glutathione; this antioxidant pathway is used a lot in red cells; this pathway uses NADPH so pentose phosphate pathway is needed |
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hemolytic anemia |
primaquine sensitivity in glucose 6 phosphate dehydrogenase deficiency- quinones can generate peroxides that damage the cell membranes ; favism- fava beans contain oxidant compounds, only G6PD pts are affected, hemolytic anemia and jaundice; heinz bodies are oxidized hemoglobin- denatured hemoglobin aggregates, covalently cross-linked; hemolysis form infection- white blood cells produce H2O2 during infection, G6PD pts have hemolysis |
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there is no fructose metabolism |
during fasting |
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prefrontal pause: compare the first signs you will see in a pt with either galactokinase deficiency or fructokinase deficiency. what symptomes would be reported? |
no symptoms only signs like elevated galactose or fructose; eventually galactose elevation produces a sign = cataracts |
