Thompson 5

Question 0

Elevated glucose (diabetes) results in increased cellular sorbitol levels in certain tissues. Which tissues? Why? What does this cause?

Answer 0

Lens, nerves, kidneys. They lack sorbitol dehydrogenase (cannot convert it to fructose). Causes cell swelling as sorbitol draws in water, which leads to cataracts, neuropathy, kidney damage.

Question 1

Glucose is converted to sorbitol using _____ and then to fructose using ______. The latter step only occurs in the _____ and ____.

Answer 1

Aldose reductase, sorbitol dehydrogenase, liver, seminal vesicles

Question 2

Non-classical galactosemia is caused by a deficiency in ______, leading to a build-up of _______ in the cell, which is then converted to _______ by _______.

Answer 2

galactokinase, galactose, galactitol, aldose reductase

Question 3

Classical galactosemia is caused by a deficiency in ______, which causes a build-up of _______.

Answer 3

Galactose-1-phosphate uridylyltransferase, galactose-1-phosphate

Question 4

In the liver, fructose is converted to F1P by _____, and then to glyceraldehyde and DHAP by ______. This enzyme is important because deficiency results in severe hypoglycemia and others symptoms because ______.

Answer 4

fructokinase, aldolase B; DHAP and glyceraldehyde are glycolytic metabolites and the cell needs them coming from glucose and fructose. Aldolase B also catalyzes F1-6BP breakdown (in the normal glycolysis pathway). Aldolase B deficiency is known as ‘hereditary fructose intolerance’ and is more severe than ‘essential fructosuria’ which is a deficiency in fructokinase.

Question 5

Glycosaminoglycans are made of repeating disaccharides consisting of an _____ and an ______. Clusters of glycosaminoglycan fibers attached to a protein core make a _______.

Answer 5

Acidic sugar, acetylated amino sugar; proteoglycan