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CMBL > Micronutrients-Vitamins > Flashcards

Micronutrients-Vitamins Flashcards

1
Q

name the fat soluble vitamins

A

vitamin A, D, E, and K

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2
Q

name the water soluble vitamins

A

Ascorbic Acid, Energy releasing B vitamins, Hematopoietic B vitamins, other B vitamins

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3
Q

Folic acid (Folate) is vitamin B__. Plays an important role in _____

A

Folate is vitamin B9.

-one-carbon atom transfers

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4
Q

what is the reduced form of folate?

A

tetrahydrofolate

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5
Q

Methotrexate inhibits ___ which prevents the formation of _____. This drug is used to treat psoriasis, rheumatoid arthritis, and neoplastic diseases

A
  • dihydrofolate reductase

- tetrahydrofolic acid (THF)

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6
Q

N10-formyl THF produces

A

purines

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7
Q

N5, N10 -methylene THF produces

A

thymidine monophosphate, serine synthesis from glycine

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8
Q

N5-methyl THF produces

A

methionine synthesis from homocysteine

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9
Q

deficiencies in which vitamins can cause macrocytic anemia?

A

deficiency in vitamin B12 or folate

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10
Q

microcytic anemia can be caused by deficiencies in which vitamins?

A

deficiency in iron, pyridoxine, and ascorbate

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11
Q

which vitamin is important to prevent neural tube defects in the fetus?

A

folate

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12
Q

a patient comes to you complaining of fatigue. The patient has a history of rheumatoid arthritis. Blood tests reveal the patient has macrocytic anemia. What medication could have caused the anemia?

A

methotrexate

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13
Q

What folate related rxn is vitamin B12 (methyl-cobalamin) present in?

A

Homocysteine and N5-methyl-tetrahydrofolate —(methionine synthase)—> methionine and tetrahydrofolate
cofactors: Vitamin B12 (methyl-cobalamin)

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14
Q

a patient presents with elevated homocysteine levels. What do vitamins do you suspect are at fault?

A

vitamin B12(methyl-cobalamin) or Folate (N5-methyltetrahydrofolate)

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15
Q

how many bonds does cobalt make in B12?

A

six

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16
Q

Which form of B12 is commercially bought?

A

cyanocobalamin

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17
Q

Is cobalamin present in plants?

A

NO! This is why strict vegans must take B12 supplements. or eat fortified cereals

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18
Q

R-protein trasnfers B12 through the ___ while Intrinsic factor transports B12 through the ___

A

stomach

intestines

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19
Q

Describe the onset of B12 deficiency

A

B12 is not like other water soluble vitamins because it is stored in the body. It may take several years for clinical symptoms of B12 deficiency to show

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20
Q

The active form of vitamin C is ___

A

ascorbic acid

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21
Q

Main function of ascorbate is as a ___ agent. Vitamin C is required for maintenance of ___ and ____

A

reducing

-normal connective tissue and wound healing

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22
Q

deficiency of vitamin C results in ___ which is best explained by ___

A

scurvy

-deficiency in the hydroxylation of collage which results in defective connective tissue

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23
Q

Vitamin B6 derivatives include

A

-pyridine pyridoxine, pryidoxal, and pyridoxamine

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24
Q

pyridine pyridoxine, pryidoxal, and pyridoxamine are all precursors to the biologically active coenzyme ____

A

pyridoxal phosphate (PLP)

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25
Q

PLP, a derivative of vitamin ___, is a coenzyme for what reactions

A

B6,

reactions involving amino acids!! **transamination

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26
Q

Which vitamin is the only water soluble vitamin with significant toxicity??

A

pyridoxine

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27
Q

Thiamine is vitamin B__

A

1

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28
Q

Thiamine Pyrophosphate is the biologically active form of vitamin __

A

B1

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29
Q

what two famous reactions require TPP?

A

pyruvate dehydrogenase and a-ketoglutarate dehydrogenase

30
Q

Beriberi is caused by what?

A

severe thiamine deficiency especially where polished rice is a staple of the diet

31
Q

Wernicke-Korsakoff syndrome

A

-a thiamine deficiency associated with chronic alcoholism

32
Q

Niacin is vitamin B__

A

niacin is vitamin B3

33
Q

What is the biologically active coenzyme forms of niacin?

A

-nicotinamide adenine dinucleotide (NAD+) and NADP+

34
Q

a deficiency of pellagra is caused by

A

niacin deficiency

35
Q

symptoms of pellagra pass through the 3 Ds, what are they?

A

dermatitis, diarrhea, dementia

36
Q

a patient comes to you and presents with scaly sores, mucosal changes, and mental symptoms. The live on a farm and eat corn every meal, you suspect____

A

pellagra due to niacin deficiency

37
Q

Niacin can decrease ___

A

circulating FFA levels by inhibiting lipolysis. reduction of FFAs leads to decreased in liver triglyceride synthesis

38
Q

Riboflavin is vitamin B___

A

riboflavin is vitamin B2

39
Q

what are the two biologically active forms of riboflavin?

A

FMN and FAD: these both reversibly accept two hydrogen atoms

40
Q

Biotin is vitamin B___

A

vitamin B 7

41
Q

deficiencies of biotin are extremely rare because biotin is widely distributed in food and intestinal bacteria make it. What product could potentially cause biotin deficiency?

A

raw eggs because avidin tightly binds biotin but for a problem it would require around 20 raw eggs a day

42
Q

Pantothenic acid is vitamin B__

A

B5

43
Q

pantothenic acid is a component of ___

A

coenzyme A

44
Q

dietary retinol is better known as Vitamin __

A

Vitamin A

45
Q

T or F: retinoic acid can be reduced to derive retinal or retinol

A

False. There is no mechanism in humans for
the reduction of retinoic acid and therefore
retinoic acid cannot be used to derive either
retinal or retinol

46
Q

B-carotene can be cleaved i the intestine to yield two molecules of retinal. Is this conversion effecient?

A

NO, vitamin A activity of B-carotene is a fraction of retinol

47
Q

what other compound that we know of does Vitmain A act like?

A

Steroid hormones.

48
Q

describe how retinol travels in blood

A

retinol travels in plasma by retinol-binding protein

49
Q

how does retinol act in target tissues

A

retinol is oxidized to retinoic acid which binds to nuclear receptors

50
Q

why does vitamin A deficiency result in night blindness?

A

11 cis retinal is a component of rhodopsin (the visual pigment)

51
Q

retinol is oxidized to ____. ____ binds with high affinity to specific receptor proteins present in the nucleus of target tissues like epithelial

A

retinoic acid, retinoic acid

52
Q

T or F: retinoic acid has a vital role in reproduction and the visual cycle

A

F: Animals given retinoic acid only
as their source of vitamin A from birth are blind
and sterile

53
Q

acne and psoriasis can be treated with

A

retinoic acids or derivatives

54
Q

xeropthalmia

A
  • a pathological dryness of the conjunctiva and cornea
  • due to vitamin A deficiency
  • most commonly seen in children in developing tropical countries
55
Q

Isotretinoin

A

-isomer of retinoic acid
a teratogen
contraindicated in women of childbearing potential unless severe, disfiguring acne and adequate birth control must be used while on it

56
Q

The active molecule of Vitamin D is

A

1,25-diOH-D3) calcitrol

57
Q

the most prominent actions of 1,25-diOH-D3 are

A

regulate plasma levels of calcium and phosphorus

58
Q

7-dehydrocholesterol is converted to ___ in the dermis and epidermis of humans exposed to sunlight and transported to the liver bound to vitamin-D binding protein

A

cholecalciferol (D3)

59
Q

are vitamins D2 or D3 biologically active?

A

NO

60
Q

calcidiol

A
  • the 25-hydroxycholecalciferol form

- predominant form of vitamin D in plasma and the major storage form of the vitamin

61
Q

1,25-diOH-D3 stimulates the ___ of ___ from _____

A
  • mobilization of calcium from bone

- result is increase in plasma calcium and phosphate

62
Q

1,25-diOH-D3 stimulates the intestinal absorption of

A

Ca

63
Q

How does 1,25-diOH-D3 stimulates the intestinal absorption of calcium?

A

-calcium uptake is enhanced by increased synthesis of specific calcium-binding protein, calbindin

64
Q

vitamin D deficiency results in

A

-net demineralization of bone resulting in rickets

65
Q

renal osteodystrophy

A

chronic kidney disease decreases formation of active vitamin D as well as increased retention of phosphorus

66
Q

low blood calcium triggers

A

-increase PTH which causes bone demineralization with release of calcium and phosphate

67
Q

vitamin K is required in the hepatic synthesis of blood clotting proteins ____, and ___, ___, ___

A

prothrombin, factors VII, IX, and X

68
Q

formation of functional clotting factors requires the vitamin K dependent carboxylation of several _____ to ___ residues

A

-glutamate residues to γ-carboxyglutamate

(Gla) residues

69
Q

in generating mature clotting factors, vitamin K starts in what form and gets oxidized to what form

A

-hydroquinone form (Kh)

to epoxide form KE

70
Q

warfarin

A

inhibits vitamin K epoxide reductase (VKOR) so vitamin K cant get back to hydroquinone form

71
Q

a true vitamin K deficiency is rare because it is produced by

A

-intestinal flora or obtained in diet

72
Q

why is it recommended that newborns receive a single IM dose of vitamin K?

A

-newborns have sterile guts and human milk only provides 20% of RDA for vitamin K

CMBL (22 decks)

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