Gluconeogenesis and Glycogen

Question 0

Glucose made from

Answer 0

Pyruvate, lactate, TCA cycle intermediates, most amino acids (not leucine or lysine)

Question 1

Gluconeogenesis

Answer 1

Generating glucose from metabolism

Question 2

Gluconeogenesis pathway enzymes

Answer 2

Pyruvate carboxylase, PEP carboxykinase, fructose 1,6 bisohosohatase, glucose 6 phosphatase

Question 3

PEP carboxykinase

Answer 3

Generates phosphor ok pyruvate through decarboxylase reaction, ectothermic, requires GTP

Question 4

Fructose 1,6 bisphosphatase

Answer 4

Removes PO4, exergonic, allosterically regulated, citrate stimulates, AMP inhibits

Question 5

Glucose 6 phosphatase

Answer 5

Final reaction, presence of G6Pase in ER of liver and kidney cells makes gluconeogenesis possible, muscle and brain do not do gluconeogenesis

Question 6

Cori cycle

Answer 6

Vigorous exercise ➡️ anaerobic conditions ➡️ extensive glycolysis, consumes NAD+ ➡️ buildup of pyruvate and NADH
NADH is reoxidized during reduction of pyruvate to lactate

Question 7

Regulation of gluconeogenesis

Answer 7

Citrate: positive fructose 1,6 bisphosphatase and negative phosphofructosekinase
AMP: negative fructose 1,6 bisphosphatase and positive phosphofructosekinase
ATP: negative phosphofructosekinase and pyruvate kinase
Acetyl CoA: positive pyruvate carboxylase and negative pyruvate kinase

Question 8

Role of amylases

Answer 8

Attacking as endo or branch point enzymes

Question 9

Starch metabolism

Answer 9

Unregulated, broken down to sugars, use for energy, metabolism, excess convert to glycogen and fats

Question 10

Glycogen metabolism

Answer 10

Tightly regulated, mobilized when food stored are depleted

Question 11

Glycogen synthase

Answer 11

Large glycogen particle built around a single glycogenin protein at core
First glucose linked to tyrosine -OH on the protein

Question 12

Branching reasons

Answer 12

Increase polymer solubility

Increase number of non reducing ends

Question 13

Control of glycogen metabolism

Answer 13

Homeostasis achieved by control of glycogen phosphorylase and glycogen synthase, need to have glucose available at constant concentrations

Question 14

Glycogen phosphorylase regulated

Answer 14

Allosterically activated by AMP and inhibited by ATP, G6P, caffeine

Question 15

Growth promoters of insulin

Answer 15

Positive: active transport, glycolysis, glycogen synthesis, lipid synthesis, protein synthesis
Negative: lipid breakdown, glycogenesis

Question 16

Glycogen phosphorylase activator

Answer 16

Enzyme shifts to R state, inhibitor shifts towards T state

Question 17

Glycogen phosphorylase inhibitor

Answer 17

The R,T equilibrium shifts towards T, increasing cooperativity and decreasing affinity

Question 18

Phosphorylated form phosphorylase

Answer 18

Allosterically unresponsive and turned on the apo enzyme is still allosterically regulated

Question 19

Hormones that control phosphorylase

Answer 19

Glucagon and epinephrine

Create a cascade of reactions that stimulate glycogen breakdown and inhibit glycogen synthesis in liver and muscles

Question 20

Liver glycogen breakdown

Answer 20

Glucagon ➡️ adenlyl cyclase ➡️ cAMP ➡️ cAMP dependent protein kinase ➡️ phosphorylase kinase ➡️ glycogen phosphorylase ➡️ glycogen breakdown

Question 21

Hormones that control glucose concentration

Answer 21

Insulin, glucagon, epinephrine, glucocorticoids

Question 22

Insulin stimulates

Answer 22

Glycogen synthesis

Question 23

Insulin inhibits

Answer 23

Glycogen breakdown (liver, muscle)

Question 24

Trigger of glycogen breakdown

Answer 24

Epinephrine (liver, muscle) and glucagon (liver, adipose)