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