0218 Carbohydrate Metabolism

Question 1

What are the roles/fates of carbohydrates in the body

Answer 1

Glycogen (energy storage), Glycolipids (structural), Glycoproteins (structural), Glycosaminoglycans GAGs (structural), DNA/RNA, ATP, Acetyl CoA

Question 2

What enzymes regulate glycolysis

Answer 2

Hexokinase (glucokinase in liver), PFK1 (pyruvate-fructo-kinase), GA3PDH, pyruvate kinase

Question 3

What are the commited steps of glycolysis

Answer 3

Fructose-6-P to Fructose-1,6-bis-P (PFK1) and phosho-enol-pyruvate to pyruvate (pyruvate kinase)

Question 4

What is glycolysis ? What compounds go in and what products come out?

Answer 4

the primary catabolic oxidative pathway of glucose. Glucose 6-phosphate goes in and 2 pyruvate, 2 NADH and 2 ATP come out

Question 5

Where in the cell does glycolysis occur

Answer 5

Cytosol

Question 6

How is glycolysis linked to the TCA cycle

Answer 6

It uses NAD (to NADH) in it’s pathway and produces pyruvate (goes to acetyl CoA). It also uses ATP (hexokinase/glucokinase)

Question 7

What enzyme regulates glycogen breakdown and what hormones regulate this process

Answer 7

Glycogen phosphorylase. Hormones include adrenaline and glucagon
(glycogen to glucose-1-pi)

Question 8

What enzyme regulates glycogen synthesis and what hormones regulate this process

Answer 8

Glycogen synthase. Hormones include insulin.
(glucose-1-pi to glycogen)

Question 9

What enzyme catalyzes the production of glucose-6-phosphate from glucose

Answer 9

Hexokinase (or in the liver glucokinase)

Question 10

Where is glycogen primarily stored?

Answer 10

Liver and the muscles

Question 11

What are the products of glycolysis

Answer 11

2 pyruvate, 2 ATP, 2 NADH, 2 H20, 2 H2

Question 12

What are the factors affect [glucose] in the cytosol

Answer 12

GLUT-2 transporter and Hexokinase (sometimes glucokinase)

Question 13

Give 2 examples of structural carbohydrates

Answer 13

Glycoproteins (glycolysation of carbohydrates to a polypeptide). Glycosaminoglycans (linear unbranched polymers of repeating disaccharides

Question 14

What are the names for the processes of glucose storage, glucose mobilisation from stores and glucose synthesis from smaller macromolecules

Answer 14

In order glycogenesis, glycogenolysis and gluconeogenesis

Question 15

What is the name for the principal transmembrane transporter of glucose between liver and blood

Answer 15

GLUT-2

Question 16

Where is glucokinase found

Answer 16

In hepatic cells

Question 17

Name the hormones that stimulate glycogenolysis and the mechanisms behind it

Answer 17

Adrenaline (muscles) and glucagon (liver) both stimulate glycogenolysis. Both hormones promote synthesis of cAMP (cyclic AMP) which in turn promotes the enzyme PKA (protein kinase A). PKA increases activity of glycogen phosphorylase and inhibits glycogen synthase

Question 18

Name the hormones that inhibit glycogenolysis and the mechanisms behind it

Answer 18

Insulin is a hormone that inhibits glycogenelysis. It promotes the activity of PP-1 (protein-phosphatase-1) which in turn promotes glycogen phosphorylase and inhibits glycogen synthase)

Question 19

How many molecules of ATP does glycolysis generate

Answer 19

2 ATP

Question 20

What regulates glycolysis?

Answer 20

Cellular redox state and hormones (adrenaline, insulin, glucagon)

Question 21

Can glycolysis occur under anaerobic and aerobic conditions?

Answer 21

Yes

Question 22

What is the name of the family of transporters responsible for glucose transport over a plasma membrane

Answer 22

GLUT transporters

Question 23

What is the primary difference between glycolysis under aerobic and anaerobic conditions (think NAD+)

Answer 23

Aerobic - NAD+ is regenerated via TCA cycle

Anaerobic - NAD+ is regenerated by shuting pyruvate to lactate

Question 24

True or false: under anaerobic conditions glycolysis is a major energy providor

Answer 24

True