Carbohydrates 2

Question 1

Name the important metabolite from glycolysis that is involved in triglyceride and phospholipid biosynthesis? What is the reaction involved

Answer 1

DHAP__> glycerol phosphate

glycerol-3-phosphate dehydrogenase

Question 2

Name the metabolite that alters oxygen affinity. What is the reaction?

Answer 2

1,2 bisphosphoglycerate to 2,3 bisphosphoglycerate

bisphophoglycerate mutase

Question 3

What reaction does lactate dehydrogenase catalyse?

Answer 3

NADH +H + pyruvate to NAD + lactate

Question 4

What does lactate dehydrogenase allow?

Answer 4

continuation of glycolysis in anaerobic continues, allows NAD+ to be regenerated

Question 5

What is it called if the lactate concentration of the blood exceeds 2-5mM?

Answer 5

hyperlactemia

Question 6

What is the normal lactate concentration of the blood?

Answer 6

<2mM

Question 7

What is it called if the lactate concentration of the blood is >5mM?

Answer 7

lactic acidosis

Question 8

What are the two enzymes involved in fructose metabolism what are the products of the reactions they catalyse?

Answer 8

fructokinase–> fructose-1-phosphate

Aldolase b –> glyceraldehyde 3 phosphate

Question 9

What happens if fructokinase deficient?

Answer 9

essential fructosuria

fructose in urine only clinical sign

Question 10

What happens if aldolase b missing?

Answer 10

fructose intolerance

fructose -1-phosphate accumulates and is toxic to the liver

Question 11

What are the 3 key enzymes in galactose metabolism? What happens if any one is deficient?

Answer 11

galactokinase
galactose -1-phosphate uridyl transferase
UDP-galactose 4- epimerase
galactosemia

Question 12

What accumulates in a galactokinase deficiency?

Answer 12

galactose

Question 13

What accumulates if transferase is deficient?

Answer 13

galactose and galactose -1-phosphate

Question 14

What is pathway does galactose enter if it accumulates? What is the result of the activation of this pathway?

Answer 14

aldose reductase catalyses production of galactitol
requires NADPH
NADPH depleted effecting protein tertiary structure causing things such as cataracts as the proteins in the lens of the eye crystallise

Question 15

What enzyme is key int he pentose phosphate pathway? What reaction does it catalyse?

Answer 15

oxidative decarboxylation by glucose 6-p dehydrogenase

g-6-p to 5c sugar phosphates

Question 16

Functions of pentose phosphate pathway ?

Answer 16

genrate NADPH and produce 5c sugars for nucleic acids

Question 17

What is the result of a glucose-6-p dehydrogenase deficiency?

Answer 17

NADPH deficient therefore structural integrity of proteins not maintained resulting in things such as cataracts and RBC aggregation