Final: L2/3-Ch. 10 Flashcards
Which of the carotenoid pigments has the greatest vitamin A activity?
a. alpha-carotene
b. beta-carotene
c. gamma-carotene
d. delta-carotene
b. beta-carotene
Choose the food that is high in vitamin A palmitate.
a. spinach
b. liver
c. carrots
d. pumpkin
b. liver
Formation of retinol from beta-carotene requires the presence of what B vitamin?
a. ascorbic acid
b. folic acid
c. niacin
d. pyridoxal phosphate
c. niacin
What happens to retinal in the enterocyte?
a. it is esterified
b. it is reduced to retinol
c. it is transported into the portal blood
d. 15, 15’ dioxygenase acts to form beta-carotene
a. it is esterified
Choose the ONE correct statement.
a. Beta-carotene is hydrolyzed in the jejunum before it is absorbed.
b. Retinol does not need to form a micelle to cross the USW.
c. Beta-carotene dioxygenase activity occurs in the lumen of the ileum.
d. Retinol must be re-esterified to be carried in the chylomicron.
d. Retinol must be re-esterified to be carried in the chylomicron.
In order to be carried in the chylomicron, retinol (once in the enterocyte) is _____.
a. esterified by lecithin retinol acyl transferase
b. converted to retinaldehyde by retinaldehyde reductase
c. attached to a VLDL
d. attached to an RXR receptor on the nucleus
a. esterified by lecithin retinol acyl transferase
The majority of vitamin A is stored in the liver, while carotenoids are stored mainly in the _____ tissue.
a. muscle
b. eye
c. adipose
d. skin
c. adipose
In what cells will you find most of the retinol and vitamin A stored?
a. stellate
b. gallbladder
c. fundus
d. antrum
a. stellate
- How will retinol, once secreted from the liver, be found in the blood?
a. attached to RBP and transthyretin
b. attached to albumin
c. attached to a chylomicron
d. attached to RBP and stellate cells
a. attached to RBP and transthyretin
- Which of the following is needed for the visual cycle?
a. 11-cis retinal
b. 9-cis retinoic acid
c. lycopene
d. cryptoxanthin
a. 11-cis retinal
Vitamin A functions in the visual cycle. This mechanism involves a vitamin A molecule called A , combining with B to form C . When photon energy strikes this molecule, it splits and causes a conformational change in the molecule, causing an electrical signal to be sent to the brain.
Blank A, B, C
a. rhodopsin
b. 11-cis retinal
c. all-trans retinal
d. retinol
e. opsin
f. retinoic acid
b. 11-cis retinal
e. opsin
a. rhodopsin
Within the nucleus, all trans-retinoic acid and/or 9-cis retinoic acid binds to
_____.
a. nuclear retinoic acid receptors
b. mannosylated glycoproteins
c. cell aggregates
d. transcription factors
a. nuclear retinoic acid receptors
Why is retinoic acid considered a hormone?
a. It has receptors on the nucleus and causes a change in protein synthesis.
b. It has a biologic function similar to insulin.
c. It is synthesized in the same tissue that it affects.
d. It causes the catabolism (break down) of body proteins.
a. It has receptors on the nucleus and causes a change in protein synthesis.
- Which vitamin directs cellular differentiation of epithelial cells?
a. riboflavin
b. vitamin K
c. vitamin E
d. vitamin A
d. vitamin A
- Where would you find retinoid X receptors (RXR)?
a. cytosol
b. nucleus
c. mitochondria
d. none of the above
b. nucleus
- Which vitamin is said to be essential for growth and immune system function?
a. K
b. A
c. D
d. E
b. A
Which is NOT related to the functions of vitamin A?
a. neurological function
b. growth
c. immunity
d. cell differentiation
a. neurological function
Choose the correct statement about the quenching of singlet oxygen by carotenoids.
a. Carotenoids donate an electron to the singlet oxygen to make it stable.
b. Carotenoids covalently bond with the singlet oxygen to make it stable.
c. Carotenoids donate energy so that the excited electron returns to its orbital.
d. Carotenoids absorb the extra energy that is held by the singlet oxygen.
d. Carotenoids absorb the extra energy that is held by the singlet oxygen.
Which is the strongest antioxidant?
a. beta-carotene
b. alpha-tocopherol
c. beta-cryptoxanthin
d. lycopene
d. lycopene
Would you recommend β-carotene supplementation to a smoker to decrease risk to lung cancer?
a. Yes—β-carotene can quench singlet oxygen.
b. Yes—smoking increases free radical formation; β-carotene can decrease
free radicals.
c. No—β-carotene supplements may be harmful to smokers and are their use is not advised for the general public.
d. No—β-carotene supplements can cause a vitamin A toxicity and liver cirrhosis.
c. No—β-carotene supplements may be harmful to smokers and are their use is not advised for the general public.
Choose the phrase which best explains the following statement: “β-carotene is no magic bullet.”
a. β-carotene does not decrease the reactivity of singlet oxygen molecules.
b. β-carotene is not the only health-promoting molecule in fruits and vegetables.
c. β-carotene supplements cannot be manufactured cheaply enough.
d. β-carotene can replace vitamin E in terminating the auto-oxidation of fatty acids.
b. β-carotene is not the only health-promoting molecule in fruits and
Which micromineral deficiency interferes with vitamin A metabolism by reducing retinol-binding protein?
a. manganese
b. zinc
c. selenium
d. iron
b. zinc
Which symptom of a vitamin A deficiency is most likely responsible for deficiency-related deaths?
a. its function as a teratogen
b. poor cellular differentiation and growth
c. keratinization of the cornea
d. severe infections
d. severe infections
An individual with poor vitamin A status would have a _____ RDR than someone with a good vitamin A status.
a. greater
b. lesser
a. greater
Which vitamin D molecule would you expect to see in fortified foods?
a. ergocalciferol – vitamin D 2
b. calcidiol – 25-OH D 3
c. calcitriol – 1,25-OH 2 D 3
d. cholecalciferol – vitamin D 3
d. cholecalciferol – vitamin D 3
It’s a good thing that milk is fortified with vitamin D so that we can consume the RDA if we drink the recommended number of glasses of milk each day. The DRI for 9-69 year olds is 600 IU (15 micro g). This equals _____ cups of milk.
a. two
b. three
c. four
d. six
d. six
What % of vitamin D from the diet is absorbed?
a. 20
b. 30
c. 40
d. 50
d. 50
Dietary cholecalciferol must be further hydroxylated in order to be active vitamin D. The first hydroxylation occurs in the _____ to produce _____.
a. liver, 25-hydroxycholecalciferol
b. kidney, 25-hydroxycholecalciferol
c. skin, 7-dehydrocholesterol
d. kidney, 1-hydrocholesterol
a. liver, 25-hydroxycholecalciferol
What form of vitamin D is the major circulating form with a half-life of approximately 3 weeks?
a. calcidiol
b. calcitriol
c. cholecalciferol
d. vitamin D 2
a. calcidiol
Which vitamin is believed to function like a steroid hormone?
a. choline
b. vitamin A
c. vitamin D
d. vitamin E
c. vitamin D
Choose the non-genomic effect of vitamin D.
a. increased synthesis of calbindin
b. bone accretion
c. rapid calcium absorption
d. intracellular cytosolic signal transduction
d. intracellular cytosolic signal transduction
The vitamin D response element (VDRE) is found
a. on the enterocyte membrane.
b. on the renal tubule.
c. in the nucleus.
d. in the pancreatic duct cell.
c. in the nucleus.
Which vitamin has as its primary function the maintenance of calcium homeostasis?
a. A
b. D
c. E
d. K
b. D
Choose the correct order of the phrases below to explain the response of the
body to a decline in serum calcium levels. Choose the BEST answer.
- Increased release of PTH
- Decreased release of PTH
- Increased synthesis of calbindin
- Increased synthesis of 1,25-(OH) 2 D 3
- Increased bone absorption
- Increased calcium absorption
- Decreased bone resorption
- Increased calcium excretion
- Increased bone resorption
a. 1, 5, 4, 8
b. 1, 3, 5, 9
c. 2, 3, 9, 6
d. 1, 4, 3, 6
d. 1, 4, 3, 6
What vitamin is associated with diminished proliferation and enhanced differentiation of cells, which serves as a basis for its use as treatment of skin diseases such as psoriasis?
a. A
b. E
c. K
d. D
d. D
The RDA for vitamin D for people over the age of 70 is _____ the RDA for teenagers.
a. greater than
b. less than
c. equal to
a. greater than
A deficiency of which vitamin is commonly associated with rickets?
a. A
b. D
c. E
d. K
b. D
Sun exposure does not cause hypervitaminosis D because _____.
a. cutaneous production of the vitamin reaches a maximum
b. sunburned skin is not sensitive to the UV wavelength that causes previtamin D 3 synthesis
c. inactive products are synthesized from pre-vitamin D 3 and D 3
d. vitamin D-binding protein is not saturated with D 3
a. cutaneous production of the vitamin reaches a maximum
Which tocopherol form provides the most vitamin E activity in the U.S. food supply?
a. alpha
b. beta
c. gamma
d. delta
a. alpha
How does alpha-tocopherol differ from beta-tocopherol?
a. saturation of side chain
b. location of methyl groups
c. source in the diet
b. location of methyl groups
Who discovered vitamin E?
a. Evans and Bishop
b. McCollum and Davis
c. Mellanby and Hopkins
d. Simon and Garfunkel
a. Evans and Bishop
A genetic deficiency in _____ leads to a vitamin E deficiency syndrome.
a. RRR alpha-tocopherol
b. gamma-tocotrienol
c. tocopherol carrier protein in the jejunum
d. alpha-tocopherol transfer protein in the liver
d. alpha-tocopherol transfer protein in the liver
Immediately following a balanced meal that contained vitamin E (such as fortified milk), where would you most likely find most of the vitamin E in the body?
a. in the portal blood as α-tocopherol
b. in the general circulation bound to RBC
c. inside cells as free α-tocopherol
d. stored in adipose tissue
e. in chylomicrons in the lymphatic vessels and general circulation
e. in chylomicrons in the lymphatic vessels and general circulation
In what type of tissue is the largest amount of vitamin E stored?
a. adipose
b. heart
c. lung
d. brain
a. adipose
Which fat-soluble vitamin has as its principal function the maintenance of
membrane integrity?
a. vitamin D
b. vitamin E
c. vitamin A
d. vitamin K
b. vitamin E
Which vitamin is associated with improved plasma membrane structure and
glucose transport/metabolic control in people with type 2 diabetes?
a. A
b. D
c. E
d. K
c. E
For which vitamin is the Tolerable Upper Intake Level set because of increased tendency for bleeding?
a. A
b. D
c. E
d. K
c. E
Which of the fat-soluble vitamins is consumed in the form of phylloquinone
from plant foods?
a. A
b. D
c. E
d. K
d. K
Which fat-soluble vitamin appears to operate as a coenzyme that modifies
proteins to bind with calcium?
a. A
b. β-carotene
c. E
d. K
d. K
The action of vitamin K is the post-translational synthesis of blood clotting
factors occurs:
a. in the blood.
b. in the liver.
c. in the small intestine.
d. in the bone marrow.
b. in the liver.
Anticoagulant drugs that act by inhibiting vitamin K activity do so by which mechanism?
a. inhibiting the formation of the active form of vitamin K
b. interfering with micelle formation so vitamin K is not absorbed
c. not allowing calcium to interact with Gla residues
d. stimulating osteocalcin synthesis
a. inhibiting the formation of the active form of vitamin K
Mr. S. takes warfarin due to his valve replacement surgery. He is an avid gardener and enjoys eating the many green leafy vegetables he grows. You caution Mr. S. to tell his physician about this because the amount of warfarin he takes may need to be _____
a. decreased
b. increased
b. increased
Risk of vitamin K deficiency is greatest in:
a. newborns.
b. children.
c. adolescents.
d. older people.
a. newborns.
Vitamin K deficiency in adults is most likely due to:
a. oxalic acid in food.
b. achlorhydria.
c. antibiotic therapy.
d. a high-fiber diet.
c. antibiotic therapy.
For which vitamin is a severe deficiency associated with an increased tendency for bleeding?
a. A
b. D
c. E
d. K
d. K
Induction of a protein (i.e., increasing the amount of a protein) via increasing gene expression can be accomplished by:
a. vitamin A.
b. folate.
c. vitamin C.
d. more than one of these vitamins
a. vitamin A.
T/F
Gut bacteria can produce some vitamins, but this rarely contributes to our requirements because they are not absorbed.
False
Explanation: Vitamin K, folate, biotin—all contribute to the requirement.
T/F
Because β-carotene can be converted into retinol, plant sources are referred to as preformed vitamin A.
Explanation: Plant sources are provitamin A.
False
Explanation: Plant sources are provitamin A.
T/F
Production of active vitamin D requires skin, sunlight, cholesterol, the liver, and the kidneys.
True
T/F
Calcium homeostasis in the blood depends on intestinal absorption, bone resorption, and kidney reabsorption.
True
T/F
Many anticoagulants inhibit the vitamin K cycle, thereby preventing activation of clotting proteins.
True
T/F
All three forms of vitamin A (retinol, retinal, retinoic acid) are stored in the liver as retinyl esters.
False
Explanation: Only retinol is stored in the liver, as retinyl esters.
T/F
Vitamin D increases the abundance of calbindin (Ca ++ transporter) in enterocytes by increasing the transcription of the calbindin gene.
True
T/F
Rhodopsin is simply the opsin protein after it has been activated by 11-cis- retinal.
True
T/F
Many anticoagulants work by inhibiting the regeneration of active vitamin K (i.e., dihydrovitamin KH 2 ) during the vitamin K cycle.
True
T/F
All of the functions of vitamin A are carried out by retinoic acid via transcriptional mechanisms.
False
Explanation: E.g., retinal for the visual cycle.
T/F
A good source of vitamin D is milk, because it is fortified with 1,25-(OH) 2 -vitamin D 3 .
False
Explanation: Fortified with vitamin D 3 (cholecalciferol)—not hydroxylated at either carbon 25 or carbon 1.
T/F
7-dehydrocholesterol is the form of vitamin D that is added to fortify milk.
False
Explanation: Cholecalciferol is the form added to fortify milk.
Function:
Needed for binding with opsin in the photoreceptor rod cells
What is the Vitamin?
11-cis retinal
Function:
transported into nucleus to affect gene transcription of keratin proteins
What is the Vitamin?
retinoic acid
Function:
donates hydrogens to terminate propagation of membrane lipid peroxidation chain reactions
What is the Vitamin?
alpha-tocopherol
Function:
interacts with nuclear VDR to increase calbindin
What is the Vitamin?
calcitriol
Function:
required for carboxylation of glutamic acid
What is the Vitamin?
hydroquinone (KH 2)
