glycolysis

Question 1

GLUT 1

Answer 1

• present in RBCs, brain, kidney
• glucose uptake

Question 2

GLUT 2

Answer 2

• in hepatocytes membrane
• transports glucose into cells when blood sugar is high

Question 3

GLUT 3

Answer 3

• brain & kidney
• glucose uptake

Question 4

GLUT 4

Answer 4

• in heart, skeletal muscle, adipose (fat cells)
• insulin-stimulated glucose uptake
• when insulin level is high (usually after eating), GLUT 4 translocates to the cell surface to increase glucose uptake

CLINICAL APPLICATION:
-in diabetes mellitus, GluT4 is reduced, and the cells become resistant to insulin i.e. they don’t respond to insulin effectively, and only half the normal amount of cells take in glucose from the blood, leading to high blood sugar levels.

Question 5

Glycolysis also called (“— pathway”)

Answer 5

Embden Meyerhof pathway

Question 6

Which reactions in glycolysis cost ATP?

Answer 6

1. Glucose —> Glucose-6-phosphate (hexokinase)
2. Fructose-6-phosphate —> Fructose-1,6-biphosphate (Phosphofructokinase 1 (PFK1))

Question 7

Which reactions produce ATP in glycolysis?

Answer 7

1. 1,3-biphosphoglycerate (1,3 BPG) —> 3-phosphoglycerate (phosphoglycerate kinase)
2. phosphoenolpyruvate —> pyruvate (pyruvate kinase)

Question 8

Which reaction costs 1 NAD+?

Answer 8

Glyceraldehyde-3-phosphate —> 1,3-biphosphoglycerate (Glyceraldehyde-3-phosphate dehydrogenase)

Question 9

Which are the rate regulatory steps of glycolysis?

Answer 9

1. Glucose —> Glucose-6-phosphate (hexokinase)
2. Fructose-6-phosphate —> Fructose-1,6-phosphate (PFK1) MOST IMP
   F-1,6-PHOSPHATE ACTIVATES PYRUVATE KINASE
3. Phosphoenolpyruvate —> Pyruvate (pyruvate kinase)
   feed forward regulation
   In liver, pyruvate kinase is activated by F-1,6-PHOSPHATE

Question 10

Which high energy phosphate compounds donate phosphorylation group to ADP to form ATP

Answer 10

1,3-BPG & phosphoenolpyruvate

Question 11

How are small amounts of ATP produced in anaerobic conditions?

Answer 11

NAD+ oxidizes Glyceraldehyde-3-phosphate

Question 12

Equation of glycolysis

Answer 12

Glucose+ 2ADP+ 2NAD + 2Pi —> 2Pyruvate + 2ATP + 2NADH + H+

Question 13

Which pathway is the only source of energy in RBCs and skeletal muscles

Answer 13

Glycolysis

Question 14

Which pathway provides carbon skeletons for synthesis of non essential amino acids & glycerol for fat

Answer 14

Glycolysis

Question 15

Most of the reactions of glycolysis are reversible which are then used for?

Answer 15

Gluconeogenesis