Midterm Flashcards
(232 cards)
1
Q
which of these foods contain niacin
A) meat
B) poultry
C) fish
D) cereals
E) all of the above
A
all of the above
2
Q
niacin in bran
A
NOT Absorbable
3
Q
food form of niacin
A
NAD and NADP
4
Q
humans can produce niacin from _______
A
tryptophan
5
Q
does the average U.S. diet contain enough niacin?
A
contains enough protein to source niacin from tryptophan
6
Q
absorbable form of niacin
A
NMN, nicotinamide, and nicotinic acid
7
Q
main form of niacin into portal circulation
A
nicotinamide
8
Q
how does niacin get converted from its food form to its absorbable form?
A
enzymatic degradation
9
Q
3 pathways for NAD synthesis
A
de novo pathway, salvage pathway, Preiss-Handler pathway
10
Q
de novo pathway requires which 3 vitamins for NAD synthesis
A
iron, riboflavin, vitamin B6
11
Q
Preiss-Handler pathway converts _________ to __________
A
nicotinic acid to NAD
12
Q
de novo pathway (niacin) converts _________ to __________ and __________
A
tryptophan to NAD and acetyl CoA
13
Q
salvage pathway converts _________ to _____________
A
nicotinamide to NAD (and back via sirtuins)
14
Q
a high fat diet, high leucine diet, and diabetic ketosis ______ niacin synthesis, by inducing _________, pushing the pathway toward ____________
A
a high fat diet, high leucine diet, and diabetic ketosis (REDUCE) niacin synthesis, by inducing (ACMS decarboxylase), pushing the pathway toward (Acetyl CoA production)
15
Q
main form of niacin in blood circulation
A
nicotinamide
16
Q
functions of NAD from niacin
A
coenzyme and substrate
17
Q
histone deacetylation -> chromatin ___________
A
histone deacetylation -> chromatin (CONDENSATION)
18
Q
histone acetylation -> chromatin ___________
A
histone acetylation -> chromatin (RELAXATION)
19
Q
SIRTS promote chromatin __________ through ___________
A
SIRTS promote chromatin condensation through ADP-ribosylation
20
Q
PARP promotes chromatin __________
A
PARP promote chromatin relaxation
21
Q
oscillating NAD levels control ______________
A
the circadian clock
22
Q
a deficiency in niacin is called ____________
A
pellagra
23
Q
clinical manifestations of niacin deficiency
A
the “4 Ds”: death, diarrhea, dementia, dermatitis
24
Q
groups at risk of niacin deficiency
A
alcoholics, elderly, medication, malabsorption syndromes, genetic disorders
25
what food (not alcohol) decreases thiamin in the body and why
raw fish, due to its content of thiaminases which cleave thiamin at the methylene bridge
26
transporters of thiamin in enterocyte
ThTr2 and ThTr1
27
(ThTr2/ThTr1/both) thiamin transporters are inhibited by ________
both transporters are inhibited by ALCOHOL
28
what part of the GI tract has the greatest activity of ThTr2 and ThTr1?
greatest activity of ThTr2 and ThTr1 in the upper jejunum (early part of small intestine)
29
(ThTr2/ThTr1) has high capacity and low specificity
ThTr1
30
(ThTr2/ThTr1) has low capacity, high specificity, and expression increases with low intake of its transported vitamin
ThTr2
31
ThTr1 and ThTr2 are considered (symporters/antiporters)
antiporters (thiamin in, H+ out)
32
(ThTr2/ThTr1) is found both on the apical surface and basolateral surface of the enterocyte
ThTr2
33
main form of thiamin in portal circulation
free thiamin
34
disease characterized by a genetic mutation of the gene that encodes ThTr1
Rogers syndrome
35
turnover of thiamin in the body is (fast/slow)
fast
36
~90% of thiamin in circulation is in red blood cells as _________
TDP
37
TDP-dependent biochemical reactions
decarboxylaton of α-ketoacids to acyl-coA derivatives and interconversion of sugar phosphates for the pentose phosphate pathway
38
three enzymes that are TDP-dependent in generating ATP (yes, these enzyme names we need to know)
pyruvate dehydrogenase, α-ketoglutarate dehydrogenase, branched chain amino acid dehydrogenase
39
foods commonly containing thiamin
meats, cereals and grains, legumes and fruits
40
a deficiency in this vitamin is most commonly the cause of the first symptoms of malnutrition in an individual or population
thiamin
41
a deficiency of thiamin is called _______
beri beri
42
test to determine thiamin status
red blood cell transketolase and transketolase activation coefficient
43
groups uniquely at risk for thiamin deficiency
alcoholics, and those receiving excess glucose infusion (thiamin follows glucose in its use as a cofactor for energetic reactions). additional groups include elderly, chemotherapy patients, and malabsorption syndromes
44
TDP has _______ activity
cofactor
45
food forms of riboflavin
FMN and FAD
46
food sources of riboflavin
milk and eggs (and meats, green vegetables and enriched grains)
47
absorbable form of riboflavin
riboflavin
48
transported form of riboflavin
riboflavin bound to albumin or Ig (immune)
49
the flavin group is responsible for the ___________ ability of a molecule
oxidation and reduction
50
which of the following factors interfere with the absorption of flavins?
A) alcohol
B) metals
C) caffeine
D) vitamin C
E) all of the above
E) all of the above
51
most prominent factor affecting synthesis of riboflavin
thyroid hormones
52
the body can store enough riboflavin for _______ weeks
2-6 weeks
53
in tissues, all riboflavin is _______ and _________
enzyme bound and phosphorylated
54
main excretion pathway and form of riboflavin
urine as riboflavin
55
biological functions of riboflavin
drug and lipid metabolism, oxidations and reductions
56
assessment of flavin status methods
mainly EGRAC (erythrocyte glutathione reductase activation coefficient) and red blood cell flavin levels, also urinary excretion (not reliable),
57
groups uniquely at risk of deficiency of riboflavin
schoolchildren due to low consumption of milk and eggs and athletes (potentially)
58
riboflavin transporters and most prominent riboflavin transporter
RFT1, RFT2, and RFT3. RFT2 is highly active, present in all tissues, and is inhibited by chlorpromazine, an anti-psychotic with a similar structure to riboflavin
59
chlorpromazine, a common anti-psychotic drug, has the ability to inhibit the ________ transporter, a prominent transporter of ________
chlorpromazine, a common anti-psychotic drug, has the ability to inhibit the (RFT2) transporter, a prominent transporter of (riboflavin)
60
food sources of vitamin C
fruits and vegetables (and liver)
61
adverse effects of excess vitamin C
osmotic diarrhea and higher risk of kidney stone formation
62
ascorbic acid acts as a ____________ in reactions with oxidants
electron donor (reducing agent)
63
absorption transporters of vitamin C
SVCT (sodium dependent vitamin C transporter) and GLUT (ascorbic acid as DHA)
64
SVCT transports ascorbic acid via:
A) passive diffusion
B) primary active transport
C) secondary active transport
D) none of the above
C) secondary active transport
65
SVCT is a (low specificity/high specificity) transporter
high specificity (think: scarcity of citrus fruits in nature evolved humans to uptake any vitamin C it can)
66
SVCT is a (antiport/symport) transporter
symport
67
two transporters of vitamin C
SVCT and GLUT
68
transported form of vitamin C
free in plasma ascorbic acid
69
5 functions of vitamin C
1. antioxidant
2. collagen synthesis
3. carnitine synthesis
4. catecholamine synthesis
5. peptide amidation (hormone activation)
70
excretion of vitamin C
various metabolites into urine
71
role of vitamin C in collagen synthesis and carnitine synthesis
reduces Fe (iron), the enzymatic cofactor, to restore enzymatic activity in the reaction
72
role of vitamin C in catecholamine synthesis and hormone activation
reduces Cu (copper), the enzymatic cofactor, to restore enzymatic activity in the reaction
73
vitamin C (oxidizes/reduces) free radicals as (ascorbate/dehydroascorbate)
vitamin C reduces free radicals as ascorbate
74
deficiency of vitamin C is called ____________
scurvy
75
clinical manifestations of a deficiency of vitamin C
4 "H" disease
1. hyperkeratosis
2. hypochondriasis
3. hematologic abnormalities
4. hemorrhage
76
groups at risk of vitamin C deficiency
low socioeconomic status (cannot afford fruits and vegetables), cancer patients (abundance of free radicals), idiosyncratic diets (carnivore diet)
77
food sources of biotin
ALL foods (esp. beef and liver)
78
alternative sources of biotin
bacteria can produce a small amount of biotin
79
transporter of biotin in the enterocyte
SMVT (shared multivitamin transporter)
80
SMVT is a(n) (antiport/symport) transporter
symport with Na+
81
food form of biotin
biocytin
82
absorbable form of biotin
biotin and biocytin
83
food sources of pantothenic acid
ALL foods
84
food form of pantothenic acid
coenzyme A
85
main transporter of pantothenic acid
SMVT (shared multivitamin transporter)
86
absorbable form of pantothenic acid
pantothenic acid
87
excretion pathway of pantothenic acid
urine (as panthothenic acid)
88
biological functions of pantothenic acid
metabolized to two major enzyme cofactors, coenzyme A (coenzyme A) and acyl carrier protein (ACP)
89
the two major enzyme cofactors pantothenic acid is metabolized into are ______________ and _______________
1. coenzyme A
2. acyl carrier protein
90
function and source of acyl carrier protein
metabolized from pantothenic acid, ACP tethers growing fatty acid chain for further reaction
91
assessment of pantothenic acid status
urinary excretion of pantothenic acid (PA)
92
common clinical manifestation of pantothenic acid deficiency
burning feet syndrome
93
in the synthesis of coenzyme A, as cofactored by pantothenic acid, the end product coenzyme A (promotes/inhibits) pantothenate kinase
inhibits
94
portal circulation form of vitamin B5
pantothenic acid
95
food sources of biotin
ALL foods
96
food form of biotin
biocytin
97
absorption of biotin mainly occurs in the ________________
jejunum
98
transporter of biotin in the enterocyte
SMVT (shared multivitamin transporter)
99
SMVT is a (antiport/symport) transporter
symport
100
what cells are SMVT found in?
ALL cells
101
role of holocarboxylase synthetase (HCS)
covalently attaches biotin groups to target proteins (enzymes and histones)
102
two functions of biotin
1. coenzyme
2. regulation of gene expression (noncoenzyme)
103
HCS deficiency results in the ability to utilize ______________
biotin
104
what does the biotinylation of proteins do
affects transcription of genes by modifying chromatin structure
105
assessment of biotin status
plasma and urine levels
106
2 non-enzymatic roles of biotin
1. biotinylation of proteins (modifies transcriptional proteins)
2. progression of cell cycle past G1
107
SMVT is inhibited by _________________
excess biotin
108
absorbable forms of biotin include _______ and __________
biotin and biocytin
109
food form of vitamin A
retinyl esters
110
vitamin A form relevant for vision
11-cis-retinal
111
dietary sources of vitamin A
dairy, eggs, fish, liver
112
6 functions of vitamin A
1. vision
2. growth and development
3. immunity
4. gene transcription regulation
5. bone formation and resorption
6. reproduction
113
tolerable upper limit of vitamin A is _____ than the RDA
2-3x higher
114
carotenoids have relatively (high/low) bioavailability in comparison to vitamin A
low
115
how does vitamin A enter the enterocyte?
via micelle
116
how are dietary vitamin A and carotenoids distributed to cells?
A) LDL
B) VLDL
C) chylomicrons
chylomicrons in lymph and then blood circulation. *key = DIETARY vitamin A means from a meal and not recirculated from storage, which would be VLDL and LDL
117
form and location of vitamin A storage
retinyl esters in the stellite cells of the liver
118
stellite cells
hepatic vitamin A storage cells
119
what is the main form of vitamin A in circulation during fasting, or any phase after postprandial?
retinol-RBP (retinol bound to retinol binding protein)
120
complex formed by vitamin A in circulation during fasting
retinol-RBP-TTR complex
121
STRA6
retinol-RBP specific receptor for vitamin A
122
how is vitamin A excreted?
urine and feces
123
form of vitamin A in urine
4-oxo-retinoic acid
124
form of vitamin A in feces
4-oxo-retinoic acid glucuronide
125
form of vitamin A for transcriptional regulation
retinoic acid
126
retinoic acid (increases/decreases) transcription and how
increased, by assisting in the removal of a repressor and recruitment of activator
127
(cones/rods) are associated with dim light vision
rods
128
which molecule is responsible for night vision?
A) 11-cis-retinal
B) 9-cis-retinoic acid
C) all-trans-retinol
D) β-carotenoid
A) 11-cis retinal
129
which form of vitamin A binds to retinoic acid receptor (RAR)?
all-trans-retinoic acid
130
which form of vitamin A binds to retinoid X receptor (RXR)?
9-cis-retinoic acid
131
what are the two components of rhodopsin?
opsin + 11-cis-retinal
132
what occurs when light (hv) hits rhodopsin?
the molecule splits into opsin and all-trans-retinol, and all-trans-retinol is retransformed into 11-cis-retinal in the retinal epithelium
133
in phototransduction, (hyperpolarization/depolarization) triggers the cell to transduce a visual signal to the brain
hyperpolarization
134
phototransduction pathway
rhodopsin→transducin→increase in PDE→decrease in cGMP levels→cGMP ion channels close→hyperpolarization
135
(increased/decreased) levels of cGMP facilitate a transduced visual light signal
decreased
136
vitamin A deficiency causes immune (overexpression/impairment)
impairment
137
role of vitamin A in growth and development
as seen in rat models, lack of vitamin A promotes fetal resorption and irreversible teratogenic abnormalities
138
two assessment methods of vitamin A status
plasma vitamin A levels and relative dose response assay (plasma levels measured 0 and 5 hrs post vitamin A administration)
139
groups at risk of vitamin A deficiency
premature infants, pregnant and lactating mothers in developing countries, those with liver diseases
140
cleavage of β-carotene results in what form of vitamin A?
retinal
141
how many retinal molecules does asymmetrical cleavage of a carotenoid produce?
1 retinal
141
how many retinal molecules does symmetrical cleavage of a carotenoid produce?
2 retinals
142
BCO
cleavage enzyme for carotenoids
143
what protein binds retinol to keep it in a cell
CRBP
144
dietary sources of carotenoids
orange fruits and vegetables (carrots, squah, canteloupe) and broccoli and general fruits and vegetables
145
two forms of carotenoids
carotenes and xenophylls
146
conversion of retinol to retinoic acid
retinol→retinal→retinoic acid
147
human milk is a (rich/poor) source of choline
rich
148
food chemical forms of choline
free choline, betaine, sphingomyelin, phosphatidylcholine (ester of choline)
149
dietary sources of choline
eggs, beef, plant foods
150
phosphatidylcholine is circulated as _____________________
chylomicrons in lymph
151
free choline is circulated to ______________________
the portal vein in blood
152
3 choline biological functions
phospholipid synthesis, neurotransmitter synthesis, one carbon metabolism (betaine→methionine)
153
PEMT is induced by ______________
estrogen
154
PEMT
the only enzyme capable of de novo choline synthesis in the body
155
choline deficiency may affect brain development
A) True
B) False
A) True
156
where is TMA converted to TMAO?
the liver
157
carnitine most resembles a(n):
A) amino acid
B) lipid
C) water-soluble vitamin
amino acid
158
transporter of carnitine
OCTN2
159
carnitine is synthesized from __________ and _____________
lysine and methionine
160
carnitine is highly regulated by
renal reabsorption by OCTN
161
2 functions of carnitine (yes, two)
fatty acid oxidation and transient reservoir for excess coA
162
at risk groups for carnitine deficiency
vegetarians, newborns, valproic acid (psychiatric medication) users, burn or trauma victims
163
how is coenzyme Q circulated for absorption?
in chylomicrons into lymph
164
dietary sources of coenzyme Q
lipid rich foods (meat, nuts, etc.)
165
2 functions of coenzyme Q
electron transport chain and lipoperoxidation (quenching free radicals)
166
coenzyme Q is (highly/poorly) absorbed
POORLY
167
excretion of coenzyme Q
urine and feces
168
in circulation, coenzyme Q is in the form of ____________
ubiquinol
169
coenzyme Q is synthesized endogenously from __________
acetyl coA
170
wet beri beri
chronic (often caused by calorie restriction)
171
dry beri beri
cardiovascular
172
acute beri beri
infants
173
SR-B1
saturable and competitive carotenoid micelle transporter
174
where in the cell do carotenoids have free radical quenching activity?
interior of the membrane
175
function of vitamin E
antioxidant
176
what feature structurally differentiates tocopherols versus tocotrienols
tocotrienols have double bonds
177
dietary sources of vitamin E
oils and nuts
178
adverse effects of vitamin E toxicity
increased bleeding (interferes with vitamin K)
179
what is the rate of absorption of vitamin E?
10-80% (HIGHLY variable)
180
why is α-tocopherol the predominant form of tocopherol in the body?
α-TTP (α-tocopherol transport protein) located in liver cells selectively secretes α-tocopherol to VLDL for peripheral tissue circulation
181
where is the majority (90%) of α-tocopherol stored in the body?
lipid droplets of adipose tissue
182
regeneration interactions of vitamin E (α-tocopherol)
vitamin E, vitamin C, glutathione, NAD+/NADPH
183
α-tocopherol provides _____ for the reduction of lipid carbon-centered radicals
hydrogen
184
mutated/deleted α-TTP in the liver causes ________
AVED (ataxia and vitamin E deficiency)
185
5 interfering factors that prevent vitamin E absorption
1. retinoids
2. plant sterols
3. alcohol
4. dietary fiber
5. eicosapentaenoic acid (EPA in omega 3s)
186
dietary sources of vitamin K
green leafy vegetables, turnips (plant foods)
187
absorption of vitamin K is (minimally/highly) variable
highly
188
absorption of vitamin K
passive diffusion by micelles (lipids needed), circulated via chylomicrons
189
turnover of the body's stores of vitamin K is __________ and lasts approximately ____________
turnover of the body's stores of vitamin K is rapid and lasts approximately 1.5 days
190
where in the cell is vitamin K mostly present?
cell membranes
191
how is vitamin K excreted?
conjugated with glucuronic acid and excreted via feces
192
what is the dietary form of vitamin K?
quinone
193
what is the main form of vitamin K in circulation?
quinone
194
is the dietary form of vitamin K considered biologically active?
no, it is not reduced
195
what enzyme is sensitive to warfarin?
VKOR
196
what will you recommend to a patient taking warfarin?
A) increase dietary vitamin K intake
B) decrease dietary vitamin K intake
C) maintain dietary vitamin K intake
C) maintain dietary vitamin K intake
197
2 biological functions of vitamin K
1. blood clotting
2. regulation of bone metabolism
198
vitamin K is a co-factor for the post-translational carboxylation of specific _________ residues in proteins into _____________
vitamin K is a co-factor for the post-translational carboxylation of specific (glutamic acid) residues in proteins into (γ-carboxyglutamic acid (Gla))
199
vitamin K recognizes specific _________ residues in the amino acid sequence termini of ____________ and ___________
vitamin K recognizes specific (glutamic acid) residues in the amino acid sequence termini of (prothrombin) and (osteocalcin) - γ-carboxylates them into Gla!
200
__, __, __, and __ are vitamin K-dependent coagulation proteins
(C, S, Z, and M) are vitamin K-dependent coagulation proteins
201
the presence of ____ in clotting factors allows the Ca2+ dependent associated clotting factors with phospholipids in membranes at site of injury
the presence of (Gla) in clotting factors allows the Ca2+ dependent associated clotting factors with phospholipids in membranes at site of injury
202
3 hormones that regulate calcium and phosphate
1. parathyroid hormone (PTH)
2. 1, 25-dihydroxyvitamin D3
3. calcitonin
203
low calcium levels are sensed by which glands?
parathyroid glands
204
when the _________ glands detect low levels of Ca2+, they increase levels of _________, which targets ________, ________, and _______
when the parathyroid glands detect low levels of Ca2+, they increase levels of parathyroid hormone (PTH), which targets bone, kidney, and intestine
205
mononuclear cells
occupy space after resorption has formed a depression in the bone, and recruit osteoblasts during bone remodeling
206
which is a longer process, bone resorption or bone formation
bone formation
207
two proteins released by osteoblasts in the RANKL-RANK-OPG regulatory pathway and osteoclastic bone resorption
RANK and M-CSF
208
2 physiological roles of calcium
1. structural
2. protein activation
209
transporter in reabsorption of calcium in the kidney
TRPV5
210
calbindin
protein that attaches calcium within the cell and transports it
211
NCX1
sodium calcium exchange transporter (antiport, basolateral side in enterocyte and blood side in kidney)
212
only _______% of filtered calcium is excreted
1-2.5%
213
fractional absorption of calcium during the first trimester of pregnancy increases:
A) 25%
B) 50%
C) 75%
D) >95%
D) >95% (due to hormonal regulation)
214
____% of calcium filtrated in the kidney is reabsorbed
98%
215
90% of calcium is reabsorbed by __________, (early/late) in the nephron filtering process
90% of calcium is reabsorbed by passive diffusion, early in the nephron filtering process
216
although only 10%, ______________ occurring is a major contributor to calcium balance in the body
active transport
217
intestinal absorption of calcium is carried out by
A) a transcellular, carrier-mediated transporter
B) a paracellular, passive diffusion transport
C) both
C) both
218
both absorption mechanisms (passive paracellular and active transcellular) of calcium are regulated by vitamin D
A) true
B) false
A) true
219
TRPV6
Ca2+ transporter in intestine on apical side of enterocyte
220
TRPV6 is (high affinity/low affinity) and (not saturable/saturable)
TRPV6 is HIGH AFFINITY and SATURABLE
221
on the basolateral side of the enterocyte, these two transporters push Ca2+ out into portal circulation
NCX1 and ATPase
222
what transporter allows NCX1 to maintain a gradient needed to continue its function?
Na+/K+ pump restores NA+ gradient so that sodium can flow into the enterocyte, and antiport push Ca2+ out
223
circulating form of Ca+ in blood?
free Ca2+ or protein-bound calcium (albumin, etc.)
224
fractional absorption of calcium (increases/decreases) with age
fractional absorption of calcium DECREASES with age
225
what is the average percentage of calcium absorbed by young adults?
25% (compared to 60% in infancy)
226
dietary sources of calcium
milk, yogurt, cheese, salmon and canned fish, fortified orange juice, tofu
227
green leafy vegetables are a (rich/poor) source of calcium
green leafy vegetables are a POOR source of calcium
228
5 dietary factors that decreas the absorption of calcium
1. phytic acids
2. oxalates
3. divalent cations
4. dietary fiber
5. unaborbed fatty acids
229
groups at risk of vitamin K deficiency
premature infants, patients on anticoagulant therapy, bariatric surgery patients, antibiotic users
230
biological functions of vitamin K
coagulation and bone metabolism regulation
231
assessment of vitamin K status
no single index or biomarker that clearly indicates status, plasma phylloquinone levels, prothrombin time
