NME 2.28

Question 1

describe processes of glycogen metabolism in fed state?

Answer 1

• insulin and glucose-6-phosphate activate synthase phosphate
• synthase phosphatase activates glycogen synthase
• glycogen synthase catalyzes the elongation of glycogen chain in UDP-glucose as substrate

Question 2

describe processes of glycogen metabolism in fasting state?

Answer 2

• liver glycogen is source of blood glucose
• muscle glycogen is metabolised by glycolysis to generate energy
• glucagon and adrenaline activate synthase kinase which inactivate glycogen synthase

Question 3

what activates synthase phosphatase?

Answer 3

• insulin and glucose 6-P

Question 4

what activates glycogen synthase?

Answer 4

• synthase phosphatase

Question 5

what inactivate glycogen synthase?

Answer 5

• synthase kinases

Question 6

what activates synthase kinases?

Answer 6

• glucagon

- adrenaline

Question 7

what does glycogen phosphorylase catalyse?

Answer 7

• degradation of glycogen to glucose 1-P through phosphorolysis

Question 8

what activates glycogen phosphorylase?

Answer 8

phosphorylase kinase

Question 9

what activates phosphorylase kinase?

Answer 9

activated by glucagon and adrenaline

Question 10

what inactivates glycogen phosphorylase?

Answer 10

phosphorylase phosphatase

Question 11

what activates phosphorylase phosphatase?

Answer 11

insulin and glucose

Question 12

which one convert UDP glucose to glycogen?

Answer 12

glycogen synthase

Question 13

which one converts glycogen to G1P

Answer 13

glycogen phosphatase

Question 14

what are all kinases activated by?

Answer 14

glucagon and adrenaline

acronym: KAG

Question 15

what are all phosphatase activated by?

Answer 15

insulin and glucose

acronym: PIG

Question 16

describe the consequences of defective glycogen metabolism

Answer 16

• reduce liver ability to replenish blood glucose levels

- restrict energy production in muscles leading to fatigue

Question 17

what are the requirements for gluconeogenesis?

Answer 17

• lactate
• amino acids
• glycerol
• fatty acid oxidation

Question 18

what regulates gluconeogenesis?

Answer 18

• inhibited by insulin

- stimulated by glucagon and fatty acids

Question 19

what is the role of gluconeogenesis?

Answer 19

• maintain blood glucose when the liver glycogen is depleted

Question 20

outline gluconeogenesis?

Answer 20

• reverse conversion
• pyruvate to oxaoacetate to malate to oxaloacetate then to phosphoenolpyruvate to fructose 1,6 to fructose 6-P then to glucose 6-P then glucose

Question 21

what does pyruvate carboxylase do?

Answer 21

convert pyruvate to oxaloacetate

Question 22

what does phosphoenolpyruvate carboxykinase do?

Answer 22

convert oxaloacetate to phosphoenolpyruvate

Question 23

what does Fructose 1,6-biphosphate

Answer 23

convert fructose 1,6-P to cfructose 6-P

Question 24

what is the cori cycle?

Answer 24

• when lactate is converted to glucose in liver through gluconeogenesis
• glucose is used by muscle to form lactate

Question 25

describe gluconeogenesis from amino acids?

Answer 25

- protein is used in muscle to produce amino acids through proteolysis - amino acids is converted to pyruvate then pyruvate is converted to glucose in liver

Question 26

what amino acids cannot be used for gluconeogenesis?

Answer 26

- leucine and lysine

Question 27

describe gluconeogenesis from glycerol?

Answer 27

- glycerol released from breakdown of triglyceride in adipose tissue during fasting - taken up by licer - converted to glucose by gluconeogenesis

Question 28

what are the key enzymes used for glycolysis?

Answer 28

- glucokinase - phosphofructokinase - pyruvate kinase

Question 29

what enzymes are used for gluconeogenesis?

Answer 29

- glucose 6-phosphatase - fructose 1,6-biphosphatase - pyruvate carboxylase - PEP carboxykinase

Question 30

describe how dietary carbohydrates can be converted to triaglycerides in liver?

Answer 30

- glucose converted to pyruvate through glycolysis - pyruvate converted to acetyl CoA - then converted to citrate - citrate is converted back to acetyl CoA - acetyl CoA converted to malonyl CoA - then to fatty acid

Question 31

what happens at high concentration of malonyl CoA?

Answer 31

- inhibits oxidation of fatty acid

Question 32

what happens at low concentration of malonyl CoA?

Answer 32

- stimulate oxidation of fatty acid

Question 33

does malonyl CoA need energy to form fatty acid?

Answer 33

yes, energy taken from NADPH

Question 34

which process synthesized NADPH?

Answer 34

pentose-phosphate pathway

Question 35

what activates pyruvate dehydrogenase and acetyl-CoA carboxylase?

Answer 35

activated by insulin

Question 36

what inhibits acetyl CoA carboxylase?

Answer 36

- inhibited by glucagon and fatty acid

Question 37

what inhibits pyruvate dehydrogenase?

Answer 37

- inhibited by fatty acids and NADH

Question 38

NADPH is required for?

Answer 38

- fatty acid synthesis - fatty acid chain elongation - cholestrol biosynthesis - cytochrome P450 monoxygenases - reduction of oxidised glutathione