Lecture (6) HMP Pathway Metabolism of Other Monosaccharides

Question 1

write a short note about the Oxidative non-reversible phase.

Answer 1

• Generates 2 NADPH molecules. • Glucose 6-p undergoes Dehydrogenation (2 NADPH) and
Decarboxylation (CO2) to give a pentose called ribulose 5-p, which is converted to its isomer, D-ribose 5-p.

Question 2

write a short note about the Non-oxidative reversible phase.

Answer 2

• These reversible reactions permit pentoses (produced by the oxidative portion of the pathway) to be converted to :
Fructose 6-p and Glyceraldehyde 3-p (intermediates of glycolysis)

Question 3

Glucose 6-p undergoes Dehydrogenation (2 NADPH) and Decarboxylation (CO2) to give a pentose called ribulose 5-p, by………….. enzyme

Answer 3

glucose 6 phosphate dehydrogenase

Question 4

Glucose-6-P dehydrogenase inhibited by………

Answer 4

NADPH.

Question 5

what is the Importance of the pentose phosphate pathway?

Answer 5

(1) Generation of NADPH
Functions of NADPH:
A) It is mainly used for the reductive synthesis of
fatty acids, cholesterol and steroid hormones.
B) Production of reduced glutathione in
erythrocytes and other cells.
(2) Production of ribose residues
- It is used for nucleotide, nucleic acids and
coenzyme biosynthesis.

Question 6

what are the Functions of NADPH?

Answer 6

A) It is mainly used for the reductive synthesis of
fatty acids, cholesterol and steroid hormones.
B) Production of reduced glutathione in
erythrocytes and other cells.

Question 7

NADPH can be USED AS A SOURCE OF ENERGY

T or F?

Answer 7

F, (NOT USED AS A SOURCE OF ENERGY), NADPH can be used in reductive biosynthetic reactions, such as fatty acid, cholesterol and steroid synthesis.

Question 8

NADPH is required by red blood cells (RBCs) for the……….

Answer 8

reduction of glutathione.

Question 9

what is the function of Reduced glutathione (GSH)?

Answer 9

detoxifies free radicals such as hydrogen peroxide

which damage the red blood cell.

Question 10

write a short note about Favism.

Answer 10

• It is caused by a genetic deficiency of G6PD and is characterized by hemolytic anaemia caused by the inability to detoxify oxidizing agents.

Question 11

……………………………. It is caused by a genetic deficiency of G6PD and characterized by hemolytic anaemia
caused by the inability to detoxify oxidizing agents.

Answer 11

Favism.

Question 12

Deficiency of fructose leads to……..

Answer 12

male infertility.

Question 13

what is the Importance of Fructose?

Answer 13

1- Energy production: 15% of daily energy is derived from fructose.
2- Fructose is the major energy source for spermatozoa in the seminal vesicle.

Question 14

write a short note about Fructose Metabolism.

Answer 14

A) Phosphorylation of fructose:
• By fructokinase (in the liver) to fructose-1-P.
B) Cleavage of fructose-1-phosphate :
• Fructose-1-P is not converted to fructose-1,6-BP but cleaved by aldolase B to Dihydroxyacetone phosphate (DHAP) (enter glycolysis) & glyceraldehyde (converted to glyceraldehyde-3-P by kinase).

Question 15

a patient suffers from fructoseuria, what are the diagnosis, the symptoms, and the treatment?

Answer 15

Cause: Deficiency of fructokinase
Symptoms: Asymptomatic condition (Not serious condition). * Fructose accumulates in urine.
Treatment: Fructose and sucrose must be removed from the diet.

Question 16

a patient suffers from Hereditary fructose intolerance, what are the diagnosis, the symptoms, and the treatment?

Answer 16

Cause: Deficiency of aldolase B leading to accumulation of intracellular fructose-1-phosphate.
Symptoms:
1) Damage of liver and kidney tissues.
2) Inhibition of phosphorylase enzyme. This leads to inhibition of glycogenolysis and fasting hypoglycemia.
Treatment: Fructose and sucrose must be removed from the diet.

Question 17

Damage of liver and kidney tissues and inhibition of glycogenolysis and fasting hypoglycemia are symptoms related to …………….deficiency, which leads to accumulation of……………, this disease known as………..

Answer 17

Deficiency of aldolase B
accumulation of intracellular fructose-1-phosphate.
Hereditary fructose intolerance

Question 18

Fructose accumulation in urine is a symptom related to ……………. deficiency, which leads to accumulation of………….in……….. this disease is known as………..

Answer 18

Deficiency of fructokinase
Fructose accumulation in urine
Essential fructosuria

Question 19

cataract, liver damage and severe mental retardation are symptoms of………….. disease, which have ………….. deficiency leads to……………

Answer 19

Classic Galactosemia
Galactose-1-P uridyltransferase
1) Ingested galactose accumulates in the blood leading to galactosemia and galactosuria.
2) The accumulated galactose is reduced in the eyes, nerve tissues and liver to galactitol, causing cataracts, liver damage and severe mental retardation.