Vitamins and Minerals Review Flashcards
Group 1 contents
iodine, vitamin A, vitamin D, calcium, vitamin K, phosphorus, fluoride
Iodine is used to make…
T3 hormones
Iodide accumulates in the
thyroid gland
Iodide uptake is mediated by what symporter
Na+/I- symporter (NIS)
Made as T4 in thyroid, made into T3 in __________
liver
Production of T3 and T4 is regulated by what hormone
thyroid-stimulating hormone (TSH)
What protein rich in Tyr residues do the free iodine radicals attack
thyroglobulin (THG)
What does the attack of free radicals on TGH initiate
cross-linking (conformational change)
T3 binds to what hormone in tissues to regulate gene expression
THR
Deficiency of iodine leads to
goitre (adults) or cretinism (fetal)
Vitamin A is a group of compounds known as
retinoids
Retinyl esters broken down into what
retinol + fatty acid
Retinol and beta-carotene are incorporated into ______________ for transport
mixed micelles (treated as fats)
Retinols are predominantly taken up where
the liver
Beta-carotenes are packaged into…
VLDL
Vitamin A deficiency leads to
poor cell differentiation
- night blindness, impaired cell differentiation, impaired growth, impaired fertility, fetal defects
Retinol-RBP complex brings retinol to be converted to RA, which goes to the nucleus and binds ______ & ______ transcription factors
RAR & RXR
Vitamin A toxicity leads to
liver cell death
- accumulation with no conversion, cell reaches capacity and is damaged
Vitamin D is bound to _____ in the body
DBP
Goes to the ________ for conversion or to ________________ for storage
liver for conversion
adipose tissue for storage
In the liver, the 25th carbon of vitamin D is hydroxylated to form
25-OH D
release of PTH stimulates conversion of 25-OH D to its active form _________________________ in the kidney
1,25 (OH)2 D
1,25 (OH)2 D is called…
calcitrol
Deficiency of vitamin D leads to
rickets in kids
osteomalacia in adolescents
osteoporosis in adults/elderly
Vitamin D toxicity (rare) leads to
hypercalcemia
Vitamin K form found in plants
phylloquinone
Vitamin K form found in animals
menaquinone
Vitamin K is incorporated into micelles and absorbed in the…
SI
The conversion of vitamin K from inactive to active, and back to inactive forms what residues
Gla residues
What are the forms in which calcium is carried
40% bound to albumin
10% in complexes
50% in free form
What is the channel that allows calcium from lumen to travel into the cell
TRPV5/6
What is the function of phosphorus in the body
protein phosphorylation
What is the function of fluoride in the body
mineralization of bones and teeth
Mutations of ______ lead to Lou Gehrigs disease
SOD
Vitamin E compounds….
4 tocopherols (saturated)
4 tocotrienols (unsaturated)
Tocopherols function where
a-tocopherol is RRR, so it fits in the TTP binding pocket for transfer
Tocotrienols function where
in the liver only (can’t fit into binding pocket of enzyme therefore cannot be transported)
Vitamin E deficiency leads to
hemolytic anemia
What makes TTP
the liver
What is the function of TTP
gets a-tocopherol into VLDL for transport around the body
Glutathione is glutamate and cysteine linked through a __________________
gamma-carbon
GSH is oxidized to form
GSSG
To oxidize GSH, what 2 selenoproteins are used
glutathione peroxidase
fatty acid peroxidase
Selenium deficiency leads to
Keshans disease
Selenium toxicity (rare) leads to
selenosis
Vitamin C is also known as
ascorbic acid
What transporter is used in vitamin C absorption
SVCT1 and SCVT2 (sodium dependant vitamin C transporter)
How does vitamin C play a role in the conversion of proline to proline-OH
vitamin C is the electron donor in the redox reaction
Vitamin C deficiency leads to
scurvy
Niacin is what B vitamin
vitamin B3
Nicotinic acid and nicotinamide are precursors for
NAD and NADP
NADH functions to
transfer electrons to ETC
NADPH functions as
a reducing agent in biochemical pathways
NADH plays a role in anabolism or catabolism
catabolism
NADPH plays a role in anabolism or catabolism
anabolism
Deficiency of niacin leads to
pellagra
- 4 D’s
What are the 4 D’s of pellagra
dermatitis, dementia, diarrhea and death
Riboflavin is what B vitamin
B2
Riboflavin is absorbed via what transporter
RFT2 (riboflavin transporter 2)
FAD is reduced to FADH2 via
FAD synthetase
FMN is reduced to FMNH2 via
flavokinase
Deficiency of riboflavin leads to
ariboflavinosis
Thiamine is what B vitamin
B1
Plant form of thiamine must be converted into active form ________ before digestion
TTP
Thiamine is needed for what 2 processes
pyruvate dehydrogenase complex & a-ketoglutarate dehydrogenase complex
Deficiency in thiamine leads to
dry beriberi: adults
wet beriberi: children & young adults
acute beriberi: infants
What is the function of pantothenic acid
converted from pantothenic acid (add cysteine and phosphate) to 4-phosphopantetheine, then converted from there to coenzyme A
Biotin is what B vitamin
B7
Biotin is not only found in foods, but also made by…
intestinal bacteria
What is the 2 step reaction related to biotin
- carboxylate the N in the biotin ring
- transfer the carboxyl group to another molecule
What 3 key reactions involve biotin
pyruvate carboxylation
malonyl CoA formation
conversion of propionate into glucose
What is the difference between folate and folic acid
folic acid: oxidized (fortified)
folate: reduced (natural)
What are the 3 components of folate
pterin ring, PABA, and glutamic acid
Folate is needed in what overall processes
bone marrow formation and fetal development
Folates have multiple _________ residues that need to be removed before digestion
glutamate
(but folic acid only has 1 so its fine)
Folates are converted into what bioactive compound in the intestine
5-methyltetrahydrofolate (5-methyl THF)
Deficiency in biotin leads to what
impaired DNA synthesis and repair, & megaloblastic anemia
What B vitamin is cobalamin
B12
Cobalamin (B12) is a generic term for a group of compounds called
corrinoids
B12 deficiency leads to functional deficiency in what
folate (B9)
What factor is needed to assist the absorption of B12
IF (intrinsic factor)
B12 is stored in the…
liver
Since methionine synthase (the enzyme responsible for making N5-methyl THF) is vitamin B12 dependent, what happens when one is deficient
the folate trap
- 5-methyl THF is trapped and can’t become THF to transport anything
Folate deficiency leads to
birth defects (tube or NTD)
What are the isomer types of vitamin B6
pyridoxine, pyridoxal, and pyridoxamine
Why does one with high protein intake need more B6
high protein = high transamination demand (which uses B6 molecules)
B6 is ___________________ before absorption
dephosphorylated
Conversion occurs in the…
liver
Deficiency of B6 causes
microcytic anemia
In what forms is iron found in food
heme and non-heme
Fe3+ is
ferric
Fe2+ is
ferrous
RDA is higher for women due to
menstruation
How is non-heme iron digested
HCl/proteases cleave non-heme iron from food in the stomach to release ferric iron, which is then converted to ferrous iron and taken up in the intestinal cells
What transporter takes up non-heme iron
divalent metal transporter 1 (DMT1)
How is heme iron digested
released from hemoglobin/myoglobin by proteases and taken up in the small intestine
What transporter takes up heme iron
heme carrier protein 1 (HCP1)
What are chelators
form complexes with metal ions
soluble = increases absorption
insoluble = decreased absorption
What’s an example of an enhancer of absorption for iron
vitamin C
What’s an example of an inhibitor of absorption for iron
polyphenols
What are some examples of heme dependant enzymes
catalase & thyroid peroxidase
Iron deficiency is seen in what 4 groups
children, adolescents, females, and pregnant women
Iron toxicity can lead to
hemochromatosis and hemosiderosis
What is the main function of copper
act as a coenzyme for many redox reactions
Amino acids are removed from Cu2+ before digestion via what
HCl and pepsin in stomach
Before copper can be absorbed, it must be
reduced (Cu2+ to Cu1+)
Absorbed copper is sent to _______ and incorporated into __________
liver; ceruloplasmin
Copper deficiency leads to
anemia, bone abnormalities, hypopigmentation, thrombosis
What is Menke’s disease
a genetic defect where the body cannot absorb copper sufficiently
Copper toxicity can be caused by
Wilsons disease (mutation of ATP7B gene)
Amino acids must be released from zinc before digestion, via…
HCl in stomach, enzymes in intestine
2 ways zinc can be absorbed
carrier-mediated (ZIP4) and simple diffusion
Example of enhancer chelator for zinc
organic acids
Example of inhibitor chelator for zinc
antacids
Deficiency of zinc can be caused by
phytic acid in grains (poor absorption ability)
Zinc toxicity leads to
neurological problems
Zinc toxicity leads to what deficiency
copper (due to overactivation of metallothionein)
