metabolism of other sugars

Question 1

essential fructosuria defect

Answer 1

defect in fructokinase

Question 2

consequence of essential fructosuria

Answer 2

fructose not phosphorylated, thus not trapped in cells, excreted in urine (benign)

Question 3

fructose intolerance defect

Answer 3

deficiency of aldolase B

Question 4

consequence of fructose intolerance

Answer 4

accumulation of fructose-1-P (cannot be converted to DHAP/glyceraldehyde), leads to consumption of phosphate = inhibits glycogenolysis and gluconeogenesis

Question 5

symptoms of fructose intolerance (3)

Answer 5

hypoglycemia

cirrhosis/jaundice

Question 6

galactokinase deficiency consequence

Answer 6

deficiency of galatokinase leads to increased galactose in blood

Question 7

symptoms of galatokinase deficiency (3)

Answer 7

conversion of galactose to galactitol (aldose reductase) leads to infantile cataracts, also inability to tract objects and lack of social smile

Question 8

enzyme deficiency responsible for classic galactosemia

Answer 8

galactose-1-P uridyl transferase

Question 9

symptoms of classic galactosemia (4)

Answer 9

infantile cataracts
jaundice
hepatomegaly
mental retardation

Question 10

effect of alludes reductase

Answer 10

converts glucose –> sorbitol/ galactose –> galactitol

Question 11

enzyme that converts sorbitol to fructose

Answer 11

sorbitol dehydrogenase

Question 12

what are the consequences for the tissues that lack sorbitol dehydrogenase? (4)

Answer 12

lens = cataracts
retina= retinopathy
schwann cells= peripheral neuropathy
kidneys= glomerulonephropathy