Metabolism of hexoses

Question 1

which substances are converted to glycolytic intermediates? Where do they reenter the glycolysis cycle?

Answer 1

fructose (from muscle enters by F6P, from liver enters by GAP), galactose (G6P), and mannose(F6P)

Question 2

list the structures of the pathway of fructose in the liver

Answer 2

fructose -fructo kinase- F1P - open chain F1P - F1P aldolase - glyceraldehyde and dihydroxyacetone phosphate - glyceraldehyde kinase and triose phosphate isomerase - GAP - GLYCOLYSIS

Question 3

how can glyceraldehyde turn into dihydroxyacetone phosphate?

Answer 3

gyceraldehyde - alcohol dehydrogenase - glycerol - glycerol kinase - glycerol 3 phosphate- glycerol phosphate dehydrogenase - dihydroxyacetone phosphate

Question 4

how is fructose reentering the glycolysis pathway in the muscles?

Answer 4

fructose - hexokinase - F6P

Question 5

deficiency of type B aldolases causes?

Answer 5

fructose intolerance, therefore there is an accumulation of F1P leading to decreased ATP therefore liver damage.

Question 6

FIP inhibits which 2 pathways?

Answer 6

gluconeogenesis (fructose-1,6-biphosphatase), glycogen breakdown (glycogen phosphorylase)

Question 7

galactose and glucose are?

Answer 7

C4 epimers

Question 8

list the pathway for the metabolism of galactose

Answer 8

galactose - galactokinase - galactose-1-phosphate - galactose-1-phosphate and UDP-glucose transfer their groups using galactose-1-phoshate uridylyl transferases.- G1P + UDP-galactose - G1P using phosphoglucomutase turns into G6P

Question 9

how does UDP -galactose turn bac into UDP-glucose?

Answer 9

UDP-galactose-4-epimerase

Question 10

what is galactosemia?

Answer 10

when the galactitol formation leads to cataracts. Galactose by action of aldose reductase become galatitol

Question 11

mannose and glucose are?

Answer 11

C2 epimers

Question 12

list the pathway of mannose into F6P

Answer 12

mannose - hexokinase - mannose-6-phosphate - phosphomannose isomerase - F6P

Question 13

how does DHAP turn into GAP

Answer 13

by triose phosphate isomerase

Question 14

F1P inhibits what enzymes

Answer 14

glycogen phosphorylase, and F1,6 bisphosphatase which leads to hypoglycemia

Question 15

in muscle, pyruvate is reduced to - to regenerate NAD+

Answer 15

lactate

Question 16

the lactate from muscle cells is used to

Answer 16

synthesize glucose by gluconeogenesis in the liver

Question 17

oxidative phosphorylation yields how many ATP per glucose

Answer 17

32

Question 18

ATP production is faster in : homolactic fermentation or oxidative phosphorylation

Answer 18

homolactic fermentation

Question 19

alcohol DH reduced - and regenerates -

Answer 19

acetaldehyde and NAD+

Question 20

what is the waarburg effect

Answer 20

cancer cells had rewired their mitochondria to metabolize glucose anaerobically even in the presence of O2