Hn 400 Test 4

Front 1

How the inorganic forms of selenium are regularly found in nature

Back 1

sodium selenite (Na2SeO3)
and
sodium selenate (Na2SeO4)

Front 2

the most common organic form of selenium

Back 2

selenomethionine

(selenium replaces sulfur in the structure of amino acid methionine)

Front 3

accumulates at much higher levels in the body than other forms of selenium

most common in supplements and food

nonspecifically incorporated into body proteins in place of methionine

Back 3

selenomethionine

Front 4

selenium's antioxidant function is not due to the mineral itself, but a result of _______

Back 4

selenoproteins

Front 5

selenoenzymes contain ______ as an amino acid in the active site of the enzyme

Back 5

selenocysteine

Front 6

converts hydrogen peroxide into water
antioxidant enzyme

Back 6

glutathione peroxidase enzymes
thioredoxin reductases

Front 7

iodothyronine 5'-deiodinases

Back 7

involved in the metabolism of thyroid hormones

Front 8

selenium is highly absorbed, thus selenium levels in the body are not regulated by absorption, but rather by ______ ______

Back 8

urinary excretion

Front 9

can be a problem, especially for animals living in or around a body of waterr in an area with high soil selenium levels
b/c run off from soil causes selenium to collect in the water in high levels then starts working its way up the food chain

in humans, initial symptoms are nausea, fatigue, and diarrhea
person may eventually develop hair and nail brittleness, rash or skin lesions, and nervous system abnormalities

Back 9

selenium toxicity

Front 10

questionable selenium deficiency
occurred primarily in mountainous regions of China, causing heart lesions

Back 10

Keshan disease

showed some signs more consistant with infectious diseases

Front 11

research showed that oxidative stress in selenium-deficient individuals may have caused mutations leading to a virulent form of this virus that leads to heart pathology

Back 11

coxsackie virus

in Keshan disease patients

Front 12

only function is that it is required for thyroid hormone synthesis

Back 12

iodine

Front 13

for most americans the primary route of iodine consumption is through

Back 13

iodized salt

Front 14

type of iodized salt with these characteristics:
less expensive
higher iodine content
more soluble

Back 14

potassium iodide (KI)

Front 15

type of iodized salt with these characteristics:
more stable

Back 15

potassium iodate (KIO3)

Front 16

dietary compounds that interfere with thyroid hormone production or utilization

Back 16

goitrogens

Front 17

cassava
millet
cruciferous vegetables (broccoli, cabbage, brussels sprouts)
onions
garlic
soybeans
peanuts

Back 17

examples of foods that contain goitrogens

not believed to be of clinical importance unless a coexisting iodine deficiency exists

Front 18

two primary forms of thyroid hormone

Back 18

triodothyronine (T3)

thyroxine (T4)

Front 19

the primary circulating form of thyroid hormone, which is really a prohormone that is converted to the active ____ form

Back 19

T4 thyroxine

------>

T3 triodothyronine

Front 20

enzymes that metabolize thyroid hormone

Back 20

deiodinases

three types that are selenoproteins

liver, kidney, thyroid gland --> plasma T3 production
brain, pituitary, brown adipose --> local T3 production
brain, placenta --> T3 degradation

Front 21

regulates basal metabolic rate and is important for growth and development

particularly important for brain development, but hypothyroidism also leads to decreased muscle mass and skeletal development

Back 21

thyroid hormone

Front 22

painless deficiency condition that results from the enlargement of the thyroid to help increase its ability to take up iodine

Back 22

goiter

Front 23

more serious consequence of iodine deficiency that occurs during pregnancy to the fetus
iodine deficiency during this time can lead to the mental and physical retardation known as...

characterized by severe hypothyroidism, stunted growth, speech loss, and paralysis

Back 23

cretinism

Front 24

"world's most prevalent, yet easily preventable, cause of brain damage"
NY times... cheapest way to raise world's IQ

Back 24

iodine deficiency

easy fix comes from iodization of salt

Front 25

superoxide dismutase (oxygen radical --> hydrogen peroxide) uses _______ as a cofactor

Back 25

manganese

Front 26

both the enzymes involved in the gluconeogenesis ______ _________ use manganese as cofactors

Back 26

oxaloacetate workaround

Front 27

used as cofactor for superoxide dismutase
used in oxaloacetate workaround in gluconeogenesis
used as cofactor by one enzyme in the urea cycle
used by enzymes critical to the production of proteoglycans, which are essential components of cartilage and bones, use ______ as a cofactor

Back 27

manganese

Front 28

absorption of ______ is not well understood but is believed to be pretty low (<5%)

main route of excretion is via bile in feces

Back 28

manganese

Front 29

toxicity symptoms of manganese include neurological disorders similar to schizophrenia and Parkinson's disease

Chilean miners exposed to Mn-containing dust lead to a toxicity named...

Back 29

Manganese Madness

Front 30

sensitive to heat, prolonged heating causes cleavage between the 2 rings destroying its activity

like most B vitamins, primary function is as a cofactor for enzymes

Back 30

thiamin

Front 31

thiamin alone does not commonly serve as a cofactor, but instead thiamin diphosphate, which is more commonly referred to as _______ ______

Back 31

thiamin pyrophosphate (TPP)

Front 32

thiamin uptake and absorption is believed to be an efficient process that is passive when thiamin intake is high and active when thiamin intakes are low

two thiamin transporters are involved in uptake and absorption
_____ is found on the brush border and basolateral membrane, while _____ is found only on the brush border membrane

Back 32

THTR1

THTR2

Front 33

transition reaction and one reaction in the citric acid cycle are decarboxylation reactions that use ____ as a cofactor

Back 33

TPP (thiamin)

Front 34

TPP is a cofactor for the enzyme _______
this enzyme is key in the pentose phosphate shunt (AKA hexose monophosphate shunt) pathway
important for converting 6C sugas into 5C sugars that are needed for synthesis of DNA, RNA, and NADPH

Back 34

transketolase

Front 35

in addition to cofactor roles, _____ in the form of TTP is believed to contribute in some unresolved way to nervous system function

Back 35

thiamin

thiamin triphosphate

Front 36

during the polishing process of this food, thiamin and many other nutrients are removed

Back 36

white rice (AKA polished rice)

staple food in poorer countries that have problems with thiamin deficiencies

Front 37

thiamin deficiency is also known as _______ ,which translated means "I can't, I can't"

Back 37

beriberi

Front 38

this form of beriberi primarily affects the nervous system, w/ symptoms such as loss of muscle function, numbness, and/or tingling

Back 38

dry beriberi

Front 39

this form of beriberi affects the cardiovascular system resulting in pitting edema, along w/ enlargement of the heart

Back 39

wet beriberi

Front 40

3 reasons why alcoholics are prone to becoming thiamin deficient

Back 40

1. alcohol displaces foods that are better sources of thiamin

2. liver damage decreases TPP formation

3. increased thiamin excretion

Front 41

thiamin deficiency found in alcoholics is known as...

symptoms include paralysis or involuntary eye movement, impaired muscle coordination, memory loss and confusion

Back 41

Wernicke-Korsakoff syndrome

Front 42

water-soluble B vitamin

excreting large amounts can lead to bright yellow urine

Back 42

riboflavin

Front 43

riboflavin is important for the production of these two cofactors

Back 43

flavin adenine dinucleotide (FAD)

flavin mononucleotide (FMN)

Front 44

is photosensitive, can be destroyed by light

used to be a problem with milk stored in glass containers

Back 44

riboflavin

Front 45

citric acid cycle
electron transport chain
fatty acid oxidation
niacin synthesis
neurotransmitter catabolism
antioxidant enzymes

Back 45

some of the functions of FAD and FMN

Front 46

rare condition that often occurs with other nutrient deficiencies

riboflavin deficiency

Back 46

ariboflavinosis

Front 47

inflammation of the tongue, which can be accompanied by redness or inflammation of the oral cavity

dermatitis is also frequently a symptom

Back 47

glossitis

symptom of riboflavin deficiency

Front 48

a lesion that forms at the corners of the mouth

Back 48

angular stomatitis

symptom of riboflavin deficiency

Front 49

nicotinic acid and nicotinamide

Back 49

two forms of niacin

Front 50

niacin is importnat for the production of these two cofactors

Back 50

NAD and NADP+

Front 51

unique in that it can be synthesized from the amino acid tryptophan

intermediate in this synthesis is kynurenine, many reactions occur with this and the compound of interest

riboflavin and vitamin B6 are required for two of these reactions

Back 51

niacin

Front 52

it takes approximately _____ mg of tryptophan to make ____ mg of niacin

Back 52

60
1

Front 53

required for glycolysis
required for transition reaction and at 3 different points in the citric acid cycle
required for fatty acid oxidation
required in alcohol oxidation
used in fatty acid synthesis

Back 53

NAD and NADP

Front 54

niacin deficiency

Back 54

pellagra

Front 55

the bioavailability of niacin from corn is poor unless treated with ______ to release the bound niacin

Back 55

base

Front 56

symptoms of pellagra (niacin deficiency)

Back 56

3 D's

dementia
dermatitis
diarrhea

Front 57

nicotinic acid (not nicotinamide) can improve this

Back 57

lipid profiles when given at many times the RDA

importance has been questioned by new studies that challenge our understanding of the importance of HDL and triglyceride levels to heart attack risk

Front 58

most well known of niacin toxicity symptoms

Back 58

"niacin flush"

dilation of capillaries accompanied by tingling that can become painful

other symptoms include:
gastrointestinal distress
liver damage

Front 59

HM74A or GPR109A

Back 59

nicotinic acid receptor

beneficial effects of nicotinic acid on lipid profiles and the toxic side effects are mediated through binding to this receptor

Front 60

one important function in the body, as a part of coenzyme A

Back 60

pantothenic acid

Front 61

most pantothenic acid is found in food as CoA, which is cleaved prior to absorption.

it is then taken up into the enterocyte through the _____ _______ ______ _______

approximately 50% of pantothenic acid is absorbed; it is excreted primarily in urine

Back 61

sodium-dependent multivitamin transporter (SMVT)

Front 62

a central point in metabolism

Back 62

acetyl-CoA

Front 63

believed to be the cause of "burning feet syndrome"

Back 63

pantothenic acid deficiency

Front 64

three compounds comprising vitamin B6

Back 64

pyridoxine (methylhydroxyl group)
pyridoxal (aldehyde)
pyridoxamine (aminomethyl group)

Front 65

all three forms of vitamin B6 can be activated by...

Back 65

phosphorylation

Front 66

active or cofactor form of vitamin B6

Back 66

pyridoxal phosphate

Front 67

interconversion between pyridoxine and pyridoxal phosphate has an enzyme that requires...

Back 67

FMN (riboflavin cofactor)

Front 68

in animal products, vit B6 is primarily found in these cofactor forms

Back 68

PLP (pyridoxal phosphate) and pyridoxamine phosphate

Front 69

in plants, vit B6 is primarily found as...

Back 69

pyridoxine

up to 75% in form of pyridoxine glucoside, believed to be a plant storage form

Front 70

primary circulating forms of vit B6

Back 70

pyridoxal and PLP

Front 71

a cofactor for over 100 different enzymes, most are involved w/ amino acid metabolism

without this, all amino acids would be essential

Back 71

PLP

Front 72

PLP is also required for a number of decarboxylase enzymes that are involved in the synthesis of a number of _________

Back 72

neurotransmitters

Front 73

PLP is also required by gamma-aminolevulinic acid synthetase (ALA) that is involved in _____ synthesis

Back 73

heme

Front 74

skin or scalp ailments (seborrheic dermatitis)
microcytic hypochromic anemia (small cells, low color)
convulsions
depression
confusion

Back 74

symptoms of vit B6 deficiency
(rare)

Front 75

unlike many of the B vitamins, this can produce toxicity

Back 75

vit B6

high doses taken over an extended period of time can lead to neurological damage

Front 76

some conditions which lead people to supplement vit b6

Back 76

carpal tunnel syndrome
morning sickness
premenstrual syndrom (PMS)

Front 77

two primary forms of biotin found in diet

Back 77

free biotin and biocytin (biotin bound to lysine)

Front 78

this form of biotin is believed to be highly absorbed

Back 78

free biotin

biocytin is acted upon by biotinidase, forming free biotin and lysine

Front 79

free biotin is taken up into the enterocyte via the _____ _______ ____ _______

Back 79

sodium-dependent multivitamin transporter (SMVT)

Front 80

most biotin is excreted in....

Back 80

urine

Front 81

important cofactor for carboxylase enzymes

required by enzyme that forms malonyl CoA rom acetyl-CoA in fatty acid synthesis

another carboxylase converts pyruvate to oxaloacetate in gluconeogenesis

Back 81

biotin

Front 82

also important for:

breakdown of isoleucine, leucine, methionine, and threonine
histone biotinylation (an epigenetic modification)

Back 82

biotin

Front 83

"above the genome"

Back 83

epigenetics

Front 84

two main epigenetic modifications

Back 84

DNA methylation

histone modification

Front 85

most common modification is acetylation or deactylation

Back 85

histone modification

Front 86

through ________, biotin is believed to alter cell growth, gene expression, and DNA repair

Back 86

biotinylation

Front 87

two ways of developing biotin deficiency

Back 87

mutation in biotinidase (born w/)

consumption of raw eggs
--> raw egg whites contain a protein called avidin that binds biotin and prevents its absorption
-----> cooking eggs denatures avidin

Front 88

forms of folate B vitamin

Back 88

reduced (folate) - natural form - can be destroyed by heat, oxidation, and light
oxidized (folic acid) - synthetic form - more stable form

Front 89

folic acid always exists as a ____glutamate

Back 89

monoglutamate

Front 90

90% of folate found in foods are ____glutamates

Back 90

polyglutamates

Front 91

DRI committee created this unit to account for the differences in the bioavailability of folate which is much lower than folic acid

Back 91

dietary folate equivalents (DFEs)

1 DFE = 1 ug food folate = .6 ug food folic acid = .5 ug folic acid on an empty stomach

DFE = ug food folate + (ug folic acid x 1.7)

Front 92

before folate can be taken up into the enterocyte, the extra _____ are cleaved, because monoglutamates are the preferred form for uptake into the enterocyte

Back 92

glutamates

Front 93

monoglutamates are taken up by the enterocyte by the ____ ______ _______

Back 93

reduced folate transporter (RFT, aka reduced folate carrier)

Front 94

once inside the enterocyte, the monoglutamate forms are _______ and transported into circulation through an unresolved carrier

Back 94

methylated

Front 95

thus, the methylated _______ form is the circulating form. this is transported to the liver where it is converted back to the _______ form for storage

Back 95

monoglutamate

polyglutamate

Front 96

major function of folate

Back 96

that it participates in 1-carbon metabolism

Front 97

the cofactor form of folate

Back 97

tetrahydrofolate (THF)

Front 98

in orde for THF to be formed, a methyl group is transferred to _______ (_____ ) from 5-methyl THF, forming methyl-_______

Back 98

cobalamin (vit B12)
methyl-cobalamin

Front 99

2 major cofactor functions of THF (cofactor form of folate)

Back 99

DNA synthesis - required for the synthesis of DNA bases

amino acid metabolism

Front 100

the hallmark symptom of folate deficiency is _____ ______

Back 100

megaloblastic anemia
(macrocytic anemia)

Front 101

characterized by large, nucleated, immature red blood cells

occurs b/ c folate is needed for DNA synthesis, w/o which RBCs are not able to properly divide

results in fewer, poorer functioning RBCs

Back 101

megaloblastic anemia

Front 102

a maternal _____ deficiency can lead to neural tube defects in infants

most common of these defects is spina bifida

Back 102

folate

Front 103

unique among vitamins in that it contains an element ((cobalt) and is found almost exclusively in animal products

Back 103

vitamin B12

Front 104

neither plants nor animals produce vit B12, instead it is produced by...

Back 104

microorganisms

Front 105

vitamin b12's scientific name

Back 105

cobalamin

Front 106

the 2 cofactor forms of cobalamin

Back 106

adenosylcobalamin
methylcobalamin

Front 107

_____ frees vit B12 from the proteins that it is normally bound to in food

Back 107

pepsin

Front 108

as pepsin frees vit B12 from the proteins, ___ _____ binds the free vit B12

Back 108

R protein

Front 109

in the duodenum, ____ _______ break down R protein again freeing vit B12

Back 109

pancreatic proteases

Front 110

after vit B12 has been freed from R protein by pancreatic proteases, _____ ______, then binds vit B12 and continues into the ileum to prepare for absorption

Back 110

intrinsic factor

Front 111

in the ileum, vit B12 + intrinsic factor are believed to be endocytosed by ______ (aka intrinsic factor receptor), forming an endosome inside the enterocyte

Back 111

cubulin

Front 112

inside the endosome inside of the enterocyte, vit B12 is separated from intrinsic factor, which is broken down

the free vit B12 then binds w/ ________ __ (____ ), and ________ ___ + vit B12 moves into circulation

Back 112

transcobalamin II (TC II)

transcobalamin II + vit B12

Front 113

the ___ is the primary storage site for vit B12

Back 113

liver

Front 114

uptake into the liver occurs via the binding of vit B12 + TC II to the TC II receptor, which is then endocytosed

the TC II is degraded to free the vit B12. the primary storage form in the liver is ________

Back 114

adensylcobalamin

Front 115

excretion of vit B12 occurs mainly through

Back 115

bile, little loss in urine

Front 116

vit B12 is a cofactor for these 2 enzymes

Back 116

methionine synthase

methylmalonyl mutase

Front 117

an important enzyme in 1-carbon metabolism that uses methylcobalamin as its cofactor and converts homocysteine to methionine by adding a methyl group

methionine then is converted to other compounds that serve as methyl donors

these methyl donors can donate methyl groups for methylating DNA, an epigenetic modification

Back 117

methionine synthase

Front 118

this enzyme uses adenosylcobalamin as its cofactor, and is important in the breakdown of odd chain fatty acids

less common than even chain fatty acids

Back 118

methylmalonyl mutase

Front 119

in addition to its role as a cofactor for enzymes, vit B12 is also important for preventing degradation of ____ _____ that surrounds neurons

Back 119

myelin sheaths

Front 120

2 primary symptoms of vit B12 deficiency

Back 120

megaloblastic (macrocytic) anemia

neurological abnormalities

Front 121

the same type of anemia that occurs in folate deficiency w/ fewer enlarged, immmature RBCs

occurs b/c there is not enough cobalamin to convert 5-methyl THF to THF

thus, THF is not available for normal DNA synthesis

Back 121

megaloblastic (macrocytic) anemia

Front 122

results in the nerve degeneration and abnormalities that can often proceed the development of anemia

include a decline in mental function and burning, tingling, and numbness of legs

can worsen an deficiency can be fatal

Back 122

vit B12 deficiency symptoms

Front 123

a condition of inadequate intrinsic factor production

most common cause of vit B12 deficiency

Back 123

pernicious anemia

Front 124

penicious anemia is common in ppl over the age of 50 b/c they have the condition ____ ______

this is a chronic inflammatory condition that leads to the loss of glands in the stomach ---> decreased intrinsic factor production

Back 124

atrophic gastritis

Front 125

if folate or folic acid is given during vit B12 deficiency, it can correct anemia

doesn't correct deficiency, but cures the most common symptom

not a great thing b/c ppl who are B12 deficient can still develop the more serious neurological problems w/ a condition that is harder to diagnose

Back 125

vit B12 deficiency "masking"

Front 126

a sulfur containing, nonproteinogenic amino acid

elevated levels of this have been found in ppl w/ cardiovascular disease

Back 126

homocyteine

Front 127

hypothesized that folate, vit B6, vit B12 intake could decrease the risk of cardiovascular disease

Back 127

due to conversion of homocysteine to other amino acids

studies thus far have not proven the hypothesis to be true
why???
-- haven't focused on individuals w/ elevated homocysteine levels
-- maybe homocysteine is a biomarker or indicator of cardiovascular disease but not necessarily a causative factor