Micronutrients-Vitamins Flashcards
name the fat soluble vitamins
vitamin A, D, E, and K
name the water soluble vitamins
Ascorbic Acid, Energy releasing B vitamins, Hematopoietic B vitamins, other B vitamins
Folic acid (Folate) is vitamin B__. Plays an important role in _____
Folate is vitamin B9.
-one-carbon atom transfers
what is the reduced form of folate?
tetrahydrofolate
Methotrexate inhibits ___ which prevents the formation of _____. This drug is used to treat psoriasis, rheumatoid arthritis, and neoplastic diseases
- dihydrofolate reductase
- tetrahydrofolic acid (THF)
N10-formyl THF produces
purines
N5, N10 -methylene THF produces
thymidine monophosphate, serine synthesis from glycine
N5-methyl THF produces
methionine synthesis from homocysteine
deficiencies in which vitamins can cause macrocytic anemia?
deficiency in vitamin B12 or folate
microcytic anemia can be caused by deficiencies in which vitamins?
deficiency in iron, pyridoxine, and ascorbate
which vitamin is important to prevent neural tube defects in the fetus?
folate
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?
methotrexate
What folate related rxn is vitamin B12 (methyl-cobalamin) present in?
Homocysteine and N5-methyl-tetrahydrofolate —(methionine synthase)—> methionine and tetrahydrofolate
cofactors: Vitamin B12 (methyl-cobalamin)
a patient presents with elevated homocysteine levels. What do vitamins do you suspect are at fault?
vitamin B12(methyl-cobalamin) or Folate (N5-methyltetrahydrofolate)
how many bonds does cobalt make in B12?
six
Which form of B12 is commercially bought?
cyanocobalamin
Is cobalamin present in plants?
NO! This is why strict vegans must take B12 supplements. or eat fortified cereals
R-protein trasnfers B12 through the ___ while Intrinsic factor transports B12 through the ___
stomach
intestines
Describe the onset of B12 deficiency
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
The active form of vitamin C is ___
ascorbic acid
Main function of ascorbate is as a ___ agent. Vitamin C is required for maintenance of ___ and ____
reducing
-normal connective tissue and wound healing
deficiency of vitamin C results in ___ which is best explained by ___
scurvy
-deficiency in the hydroxylation of collage which results in defective connective tissue
Vitamin B6 derivatives include
-pyridine pyridoxine, pryidoxal, and pyridoxamine
pyridine pyridoxine, pryidoxal, and pyridoxamine are all precursors to the biologically active coenzyme ____
pyridoxal phosphate (PLP)
PLP, a derivative of vitamin ___, is a coenzyme for what reactions
B6,
reactions involving amino acids!! **transamination
Which vitamin is the only water soluble vitamin with significant toxicity??
pyridoxine
Thiamine is vitamin B__
1
Thiamine Pyrophosphate is the biologically active form of vitamin __
B1
what two famous reactions require TPP?
pyruvate dehydrogenase and a-ketoglutarate dehydrogenase
Beriberi is caused by what?
severe thiamine deficiency especially where polished rice is a staple of the diet
Wernicke-Korsakoff syndrome
-a thiamine deficiency associated with chronic alcoholism
Niacin is vitamin B__
niacin is vitamin B3
What is the biologically active coenzyme forms of niacin?
-nicotinamide adenine dinucleotide (NAD+) and NADP+
a deficiency of pellagra is caused by
niacin deficiency
symptoms of pellagra pass through the 3 Ds, what are they?
dermatitis, diarrhea, dementia
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____
pellagra due to niacin deficiency
Niacin can decrease ___
circulating FFA levels by inhibiting lipolysis. reduction of FFAs leads to decreased in liver triglyceride synthesis
Riboflavin is vitamin B___
riboflavin is vitamin B2
what are the two biologically active forms of riboflavin?
FMN and FAD: these both reversibly accept two hydrogen atoms
Biotin is vitamin B___
vitamin B 7
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?
raw eggs because avidin tightly binds biotin but for a problem it would require around 20 raw eggs a day
Pantothenic acid is vitamin B__
B5
pantothenic acid is a component of ___
coenzyme A
dietary retinol is better known as Vitamin __
Vitamin A
T or F: retinoic acid can be reduced to derive retinal or retinol
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
B-carotene can be cleaved i the intestine to yield two molecules of retinal. Is this conversion effecient?
NO, vitamin A activity of B-carotene is a fraction of retinol
what other compound that we know of does Vitmain A act like?
Steroid hormones.
describe how retinol travels in blood
retinol travels in plasma by retinol-binding protein
how does retinol act in target tissues
retinol is oxidized to retinoic acid which binds to nuclear receptors
why does vitamin A deficiency result in night blindness?
11 cis retinal is a component of rhodopsin (the visual pigment)
retinol is oxidized to ____. ____ binds with high affinity to specific receptor proteins present in the nucleus of target tissues like epithelial
retinoic acid, retinoic acid
T or F: retinoic acid has a vital role in reproduction and the visual cycle
F: Animals given retinoic acid only
as their source of vitamin A from birth are blind
and sterile
acne and psoriasis can be treated with
retinoic acids or derivatives
xeropthalmia
- a pathological dryness of the conjunctiva and cornea
- due to vitamin A deficiency
- most commonly seen in children in developing tropical countries
Isotretinoin
-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
The active molecule of Vitamin D is
1,25-diOH-D3) calcitrol
the most prominent actions of 1,25-diOH-D3 are
regulate plasma levels of calcium and phosphorus
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
cholecalciferol (D3)
are vitamins D2 or D3 biologically active?
NO
calcidiol
- the 25-hydroxycholecalciferol form
- predominant form of vitamin D in plasma and the major storage form of the vitamin
1,25-diOH-D3 stimulates the ___ of ___ from _____
- mobilization of calcium from bone
- result is increase in plasma calcium and phosphate
1,25-diOH-D3 stimulates the intestinal absorption of
Ca
How does 1,25-diOH-D3 stimulates the intestinal absorption of calcium?
-calcium uptake is enhanced by increased synthesis of specific calcium-binding protein, calbindin
vitamin D deficiency results in
-net demineralization of bone resulting in rickets
renal osteodystrophy
chronic kidney disease decreases formation of active vitamin D as well as increased retention of phosphorus
low blood calcium triggers
-increase PTH which causes bone demineralization with release of calcium and phosphate
vitamin K is required in the hepatic synthesis of blood clotting proteins ____, and ___, ___, ___
prothrombin, factors VII, IX, and X
formation of functional clotting factors requires the vitamin K dependent carboxylation of several _____ to ___ residues
-glutamate residues to γ-carboxyglutamate
(Gla) residues
in generating mature clotting factors, vitamin K starts in what form and gets oxidized to what form
-hydroquinone form (Kh)
to epoxide form KE
warfarin
inhibits vitamin K epoxide reductase (VKOR) so vitamin K cant get back to hydroquinone form
a true vitamin K deficiency is rare because it is produced by
-intestinal flora or obtained in diet
why is it recommended that newborns receive a single IM dose of vitamin K?
-newborns have sterile guts and human milk only provides 20% of RDA for vitamin K
