Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MFM > Metabolism of fructose, galactose, and pentose phosphate pathway > Flashcards

Metabolism of fructose, galactose, and pentose phosphate pathway Flashcards

1
Q

Is fructose and galactose entry into a cell insulin dependent?

A

no

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

which sugars do not promote secretion of insulin

A

fructose and galactose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

which is faster: fructose metabolism or glucose metabolism

A

fructose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

fructose is phosphorylated by fructokinase to form ____

A

fructose-1-p

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

dietary fructose is metabolized mainly in the ____ by _____

A

liver by glycolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what cleaves fructose-1-p to DHAP and glyceraldehyde?

A

aldolase B

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

enzyme that turns glyceraldehyde into glyceraldehyde 3P

A

triose kinase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

DHAP to glyceraldehyde 3-P performed by what enzyme

A

triose-P isomerase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

this can be cleaved by aldolase A, B, and C

A

F1,6BP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Fructose 1-P can only be cleaved by ____

A

aldolase B

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

hereditary fructose intolerance is a deficiency in what enzyme and what gene

A

aldolase B, ALDOB gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is the consequence of having high levels of fructose 1-P accumulate due to hereditary fructose intolerance?

A

inorganic P is not available for glycolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

without Pi what happens to glycolysis and ATP production?

A

inhibited

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Decreased hepatic ATP from hereditary fructose intolerance causes _____ to become inhibited

A

gluconeogenesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Symptoms of hereditary fructose intolerance include

A

hypoglycemia
lactic acidosis
hyperuricemia
liver failure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

To prevents liver failure and possible death due to hereditary fructose intolerance ____ is removed from the diet

A

fructose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Diagnosis of hereditary fructose intolerance include:

A

gene (DNA) sequencing

fructose test in urine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Essential fructosuria is deficiency of what gene

A

KHK gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Essential fructosuria is caused by what

A

inability of fructokinase to convery to fructose 1-P

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

In essential fructosuria, hexokinase converts fructose to _____ which is metabolized in glycolysis. The hexoinase has (low or high) affinity for fructose.

A

fructose 6-P. low affinity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

when there is no threshold for fructose and it accumulates in the urine, what disease process

A

essential fructosuria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

essential fructosuria: does it have toxic metabolites and is it malignant or benign?

A

no toxic metabolites. benign

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

hepatocytes, ovaries, and seminal vessicles use what pathway to generate fructose from glucose?

A

polyol pathway

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

describe steps of polyol pathway

A
  1. glucose to sorbitol through aldolase reducase

2. sorbitol to fructose through sorbitol dehydrogenase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

kidneys, lens, retina, and schwann cells lack what enzyme that causes sorbitol to accumulate

A

sorbitol dehydrogenase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

cells that lack sorbitol dehydrogenase are

A

kidney, lens, retina, and schwann cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

accumulated sorbitol triggers what to these cells?

A

influx of water causing them to swell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

damage by sorbitol accumulation can manifest as

A

retinopathy, cataracts, and peripheral neuropathy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

uncontrolled diabetes/hyperglycemia cause lots of glucose to accumulate in cell and when sorbitol accumulates what disease processes occur

A

peripheral neuropathy, cataracts, nephropathy, and retinopathy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

mechanisms that contribute to retinopathy include

A

polyol pathway, non-enzymatic glycation, and oxidative stress

31
Q

after hydrolyzation of lactose by lactase, beta galactose must be converted to alpha galactose by

A

galactose mutarotase

32
Q

alpha galactose is converted to ____ by galactokinase

A

galactose 1-P

33
Q

UDP glucose reacts with galactose 1-P through GALT to form

A

UDP galactose and glucose 1-P

34
Q

what is rate limiting step in ultimate conversion of galactose to glucose 1-P

A

galactose1-P uridyltransferase (GALT)

35
Q

serves as donor of galactose for lactose synthesis, glycoproteins, glycolipids, and glycosaminoglycans

A

UDP-galactose

36
Q

if galactose is not in diet, _____ converts UDP-glucose to UDP galactose

A

epimerase

37
Q

epimerase does what and what is this necessary for

A

UDP glucose to UDP galactose

necessary for “milking mother” along with lastose synthesi, glycoproteins, glycolipids, and glycosaminoglycans

38
Q

galactokinase deficiency causes

A

cataracts in early life

39
Q

deficiency of galactokinase causes what enzyme to be more and to produce what byproduct that causes what disease process

A

aldolase reductase more active causing overproduction of galactitol causing cataracts

40
Q

Symptoms of GALT deficiency

A 
cataracts in early life
N,V,D (post lactose ingestion)
failure to thrive, lethargy, hypotonia
liver damage
mental retardation
41
Q

pentose phosphate pathway generates

A

NADPH and ribulose 5-P

42
Q

NADPH produced by pentose phosphate pathway provides reducing power for

A

Biosynthesis of FA/cholesterol

detox reactions

43
Q

oxidative phase of pentose phosphate pathway is

A

irreversible

44
Q

oxidative phase of pentose phosphate pathway generates

A

NADPH, 5-C ribulose 5-P, and CO2

45
Q

intermediates of pentose phosphate to get to ribulose 5-P are

A

6-phosphoglucono-alpha-lactone and 6-phosphogluconate

46
Q

what enzyme catalyzes irreversible oxidation of G6P to 6-phosphogluconolactone and what is coenzyme and what does coenzyme produce

A

glucose 6-P dehydrogenase (G6PD) which uses NADP+ as coenzyme to produce NADPH

47
Q

types of pathways that require NADPH

A

detoxification and reductive synthesis

48
Q

what tissues have pentose phosphate active?

A

liver
endocrine glands (ovaries, testes, and adrenal cortex)
early embryo and rapidly dividing cells
lactating mammary

49
Q

liver uses pentose pathway to make

A

FA/cholesterol synthesis

50
Q

endocrine glands use pentose pathway to make

A

cholesterol and steroid hormone synthesis

51
Q

early embryo and rapidly dividing cells use pentose pathway for

A

ribose-5-P for nucleic acid synthesis

52
Q

lactating mammary uses pentose pathway for what

A

FA biosynthesis

53
Q

role of NADPH in RBCs

A

get rid of ROS

54
Q

role of NADPH in phagocytic cells

A

create ROS

55
Q

highest level of G6PD is found in ____ to generate NADPH

A

phagocytes

56
Q

superoxide radicals are produced by

A

phagocytic cells

57
Q

ROS can attack

A

proteins, membrane lipids, and DNA

58
Q

major antioxidant in cells is

A

glutathione

59
Q

reduced states of glutathione contains

A

sulfhydryl group (GSH)

60
Q

glutathione does what

A

prevents oxidative damage by reducing H2O2 to water

61
Q

H2O2 requires what enzyme to turn into 2H2O

A

glutathione peroxidase

62
Q

NADPH is used by glutathione reductase to

A

restore oxidized glutathione to its original reduced state

63
Q

individual with G6PD deficiency have:

A

decreased ability to produce NADPH, thus decreased ability to keep glutathione functional

64
Q

occurs within hours of exposure to oxidative stress

A

episode hemolytic anemia

65
Q

most common triggers for hemolytic anemia

A

viral and bacterial infections

66
Q

patients with low levels of G6PD activity is likely to have

A

chronic hemolytic anemia

67
Q

drugs that may induce ROS production which produces hemolytic anemia are

A

antimalarials, sulfonamide antibiotics, or foods such as fava bean

68
Q

most common inborn error of metabolism

A

G6PD deficiency

69
Q

G6PD genetics are

A

X-linked, recessive disorde. so males are more likely to get

70
Q

additional oxidative stressors cause

A

someone with G6PD deficiency who is asymptomatic to become symptomatic

71
Q

insoluble masses caused by oxidation of SH groups related to glutathione

A

Heinz bodies

72
Q

prototype of the disease. the oldest cells have the lower enzyme activity level therefore removed in hemolytic episode

A

G6PD A (moderate)

73
Q

Class II (Mediterranean)

A

G6PD deficiency is more severe and enzyme has decreased stability

74
Q

Class I (rare)

A

is most severe. Anemia often occurs even in absence of oxidative stress

MFM (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions