Glactose And Fructose Metabolism

Question 1

Galactose metabolism

Answer 1

Once it is transported into tissues it’s phosphorylated by galactokinase into galactose 1 p and then converted to glucose 1 p by galactose 1 p URIDYLTRANSFERASE AND EPIMERASE and then it can used in glycogen synthesis or converted to glucose 6 p to enter glycolysis

Deficiency of these enzymes lead to galactosemia ( the body can’t deal with galactose thus there is elevated amounts in blood , urine and there is hypoglycemia due to decreased glucose synthesis

Question 2

Galactosemia and cataracts

Answer 2

Cataracts is a characteristic symptom with galactosemia, results from converting excess galactose to galactitol by aldose reductase in lens and thus accumulation of it causing osmotic damage and cataract

Question 3

Cataracts in diabetes

Answer 3

Diabetic patients suffer from cataract as glucose is converted to sorbitol by Aldose reductase in lens and then accumulation of it causing osmotic damage and cataract

Question 4

Fructose metabolism

Answer 4

Once transported to tissues, it is phosphorylated by either hexokinase or fructokinase ( known as keto hexokinase)

Hexokinase converts it to fructose 6 p and then PFK-1 phosphorylated to fructose 1,6 bip and so on

Fructokinase converts it to fructose 1 p and then it is cleaved by aldolase B in liver and kidney to DAHP and glyceraldehyde only , later glyceraldehyde can be phosphorylated and so on

The rate of fructose metabolism by fructokinase is more rapid than glucose metabolism as fructose 1 p bypass PFK-1 the rate limiting enzyme

Question 5

Where is fructokinase

Answer 5

In liver , kidney and small intestine