Carbohydrate Metabolism Pt 1

Question 1

4 fates of pyruvate

Answer 1

TCA cycle (O2 present)
lactic acid fermentation (O2 absent, animals)
alcohol fermentation (O2 absent, yeast)
conversion to alanine

Question 2

alcohol fermentation functions to produce…

Answer 2

NAD+

Question 3

enzyme and cofactor used in alcohol fermentation

Answer 3

alcohol dehydrogenase
TPP

Question 4

limited O2 in muscle cells
glucose not limited

Answer 4

cori cycle

Question 5

limited O2 and glucose in muscle cells

Answer 5

cahill cycle

Question 6

conversion of pyruvate to lactic acid via…

Answer 6

lactate dehydrogenase

Question 7

what happens to lactic acid in cori cycle?

Answer 7

transported to liver
turned back into pyruvate
pyruvate becomes glucose again (gluconeogenesis)
glucose transported back to muscle

Question 8

requires 3 bypass rxns

Answer 8

cori cycle

Question 9

bypass rxn #1
intermediates
enzymes

Answer 9

bypasses pyruvate kinase rxn
pyruvate to oxaloacetate via malate
uses pyruvate carboxylase & PEP carboxylkinase

Question 10

bypass rxns #2 & 3
enzymes

Answer 10

bypasses hexokinase rxn
glucose 6-phosphatase & fructose 1,6-bisphosphatase

Question 11

cori ATP loss

Answer 11

4 net

Question 12

beginning of cahill cycle

Answer 12

muscles begin to degrade into AAs

Question 13

cahill cycle initial reaction

Answer 13

glutamic acid + pyruvate –> alanine + ketoglutarate

Question 14

what happens to L-Ala in cahill?

Answer 14

transported to liver
converted to pyruvate
gluconeogenesis

Question 15

byproduct of amino acid metabolism/cahill cycle

problem?

Answer 15

ammonia; becomes urea

requires 4 more ATP to eliminate

Question 16

cahill ATP loss

Answer 16

8 net

Question 17

fructose metabolism, route A

Answer 17

fructose –> F6P via hexokinase

enters rxn 3

Question 18

fructose metabolism, route B

Answer 18

fructose –> F1P –> glyceraldehyde via fructokinase
enters rxn 5

OR glyceraldehyde –> G3P via triose kinase
enters rxn 6

Question 19

galactose metabolism

Answer 19

galactose –> galactose 1-phosphate –> G1P via phosphoglucomutase

Question 20

carrier used in galactose metabolism

Answer 20

UDP

Question 21

decreases phosphofructokinase activity (3)

Answer 21

high ATP (allosteric)
high citrate (TCA product, helps ATP bind to allosteric site)
high H+ (lactic acid)

Question 22

F6P regulation

Answer 22

self-regulating
if downstream rxns cannot keep up, converted to F26P for storage, until it is required and changed back

Question 23

glucagon results in modification of 2 enzymes…

Answer 23

phosphofructokinase 2
fructose bisphosphate 2

Question 24

decreases hexokinase activity

Answer 24

high G6P

Question 25

decreases pyruvate kinase activity (3)

Answer 25

high ATP high glucagon high alanine

Question 26

increases pyruvate kinase activity

Answer 26

F16P

Question 27

glycogenesis

Answer 27

synthesis of glycogen

Question 28

form of glucose in glycogen

Answer 28

UDP-glucose

Question 29

core protein of glycogen

Answer 29

glycogenin

Question 30

glycogenolysis

Answer 30

degradation of glycogen

Question 31

glycogenesis enzyme

Answer 31

glycogen synthase

Question 32

glycogenolysis enzyme

Answer 32

glycogen phosphorylase

Question 33

form of glucose released from glycogenolysis

Answer 33

G1P

Question 34

epinephrine action

Answer 34

increases glucose available to body increases glycogenolysis

Question 35

insulin action

Answer 35

lowers BG increases glycogenesis increases glycolysis decreases gluconeogenesis

Question 36

glucagon action

Answer 36

increases BG increases glycogenolysis decreases glycolysis increases gluconeogenesis

Question 37

2 PPP pathways

Answer 37

oxidative non-oxidative

Question 38

PPP oxidative pathway generates...

Answer 38

NADPH 5-C sugars (ribose, deoxyribose)

Question 39

PPP non-oxidative pathway generates...

Answer 39

F6P G3P used in glycolysis