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Kaplan: Biochemistry Part I > Chapter 10: Vitamins > Flashcards

Chapter 10: Vitamins Flashcards

1
Q

What type of vitamins, (lipid or water soluble) are precursors for coenzymes?

A

water-soluble

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2
Q

What are enzymes that are dependent on biotin?

A
  • pyruvate carboxylase
  • Acetyl CoA carboxylase
  • propionyl CoA carboxylase
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3
Q

What are some metabolic pathways that utilize biotin?

A
  • gluconeogenesis
  • fatty acid synthesis
  • odd-carbon fatty acids, Val, Met, Ile, Thr
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4
Q

What is the most common cause although rare, of biotin deficiency?

A

excessive consumption of raw eggs (contain avidin, a biotin-binding protein) also, biotinidase deficiency

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5
Q

Some S/E of having biotin deficiency?

A

alopecia (hair loss), bowel inflammation, muscle pain

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6
Q

Another name for B1?

A

Thiamine

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7
Q

What are the enzymes that utilize thamine?

A
  • pyruvate dehydrogenase
  • α-ketoglutarate dehydrogenase
  • Transketolase
  • Branched chain ketoacid dehydrogenase
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8
Q

What are some metabolic pathways that utilize thiamine?

A
  • PDH
  • TCA cycle
  • HMP shunt
  • Metabolism of valine, isoleucine, and leucine
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9
Q

What are some causes of thiamine deficiency?

A

alcoholism (alcohol interferes with absorption)

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10
Q

What are some signs and symptoms of thiamine deficiency?

A

Wernicke (ataxia, nystagmus, ophtal-moplegia)

Korsakoff (confabulation, psychosis)

Wet beri-beri (high output cardiac failure, fluid retention, vascular leak and dry beri-beri (peripheral neuropathy)

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11
Q

What are important enzymes that utilize niacin?

A

dehydrogenases

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12
Q

Niacin is a major component of what two coenzymes?

A

NAD(H)
NADP(H)

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13
Q

What metabolic pathways utilize niacin?

A

many

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14
Q

What are the side effects of niacin deficiency?

A

Pellagra: diarrhea, dementia, dermatitis, and if not treated death

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15
Q

Pellagra may also be related to what important deficiency?

A

deficiency of tryptophan in areas where there are lots mostly corn diet, corn is low in tryptophan which supplies a portion of the niacin requirement

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16
Q

What are important enzymes that utilize folic acid?

A

thymidylate synthase

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17
Q

What is THF?

A

Tetrahydrofolic acid is a folic acid derivative that is produced from dihydrofolic acid after conversion by dihydrofolate reductase.

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18
Q

What are metabolic pathways that folic acid is utilized in?

A

thymidine (pyrimidine) synthesis
purine synthesis

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19
Q

What is the most common cause of folic acid deficiency?

A

alcoholism and pregnancy (body stores depleted in 3 months), hemodialysis

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20
Q

What are some symptoms of folic acid deficiency?

A

homocystinemia with risk of deep vein thrombosis and atherosclerosis

megaloblastic (macrocytic anemia)

Deficiency in early pregnancy causes NTD in fetus

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21
Q

What is another name for B12?

A

cyanocobalamin

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22
Q

What are enzymes that require B12?

A

homocysteine methyltransferase
methylmalonyl CoA mutase

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23
Q

What pathways utilize B12

A

methionine, SAM

Odd-carbon fatty acids, Val, Met, Ile, Thr

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24
Q

What are the most common causes of B12 deficiency?

A

pernicious anemia

aging especially with poor nutrition, bacterial overgrowth of terminal ileum, resection of the terminal ileum secondary to Crohn disease, chronic pancreatitis, and rarely vegans, or infection with D latum

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25
Q

What are some signs and symptoms of B12 deficiency?

A

megaloblastic (macrocytic) anemia
progressive peripheral neuropathy

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26
Q

What is another name for vitamin B6?

A

pyridoxine

27
Q

What is Pyridoxal P? What does it stand for?

A

One of the active forms of vitamin B6

Pyridoxal 5’ phosphate

28
Q

What are enzymes that utilize B2?

A

dehydrogenases

29
Q

What is another name for B2?

A

riboflavin

30
Q

What coenzyme does riboflavin create?

A

FAD(H2)

31
Q

What are some S/E of riboflavin deficiency?

A

corneal neovascularization

cheilosis or stomatitis (cracking or scaling of lip borders and corners of the mouth)

magenta colored tongue.

32
Q

What are some enzymes that utilize ascorbate (C)?

A

prolyl and lysyl hydroxylases
dopamine hydroxylase

33
Q

What are some metabolic pathways that require ascorbate?

A

collagen synthesis

catecholamine synthesis

absorption of iron in GI tract

34
Q

What is the most common cause of vit. C deficiency?

A

diet deficient in citrus fruits and green veggies

35
Q

What are the signs and symptoms of ascorbate deficiency?

A

scurvy: poor wound healing, easy bruising, bleeding gums, increased bleeding time, painful glossitis, anemia

36
Q

What are the enzymes that require pantothenic acid CoA?

A

fatty acid synthase
fatty acyl CoA synthetase
pyruvate dehydrogenase
α-ketoglutarate dehydrogenase

37
Q

What are the important metabolic pathways that utilize pantothenic acid?

A

fatty acid metabolism

PDH
TCA cycle

38
Q

Is a deficiency of pantothenic acid common?

A

rare

39
Q

What is infantile scurvy?

A

when infants are 2-10 months of age who are bottle-fed with formula that is overheated for pasteurization and not supplemented with Vit. C pithed frog position

bleeding occurs same as adults but gum bleeding is not a common feature

40
Q

What is renal osteodystrophy?

A

a bone disease that occurs in adults and children with chronic kidney disease

41
Q

What are some symptoms of Vitamin D deficiency?

A

bone demineralization
rickets (children)
osteomalacia (adults)

42
Q

What are symptoms of Vitamin A deficiency?

A
  • night blindness
  • keratinized squamous epithelia
  • xeropthalmia, bitot spots
  • keratomalacia, blindness
  • follicular hyperkaratosis
  • alopecia
43
Q

Most common cause of vitamin D deficiency?

A

insufficient sunlight, inadequate fortified foods (milk), or end-stage renal disease (renal osteodystrophy)

44
Q

What are some causes of Vit. A deficiency?

A

fat malabsorption or fat-free diet

45
Q

What is vitamin E deficiency caused by?

A

caused by fat malabsorption or premature birth

46
Q

What are other names for Vit A? (as a whole not active forms)

A

carotene

47
Q

Which type of vitamin A is important in rod and cone cells for vision?

A

retinal

48
Q

Which type of vitamin A is important as a growth regulator especially in epithelium?

A

retinoic acid and retinol

49
Q

Other names for Vitamin K?

A

Menaquinone, bacteria; phytoquinone, plants

50
Q

What are the important functions of vitamin K?

A

carboxylation of glutamic acid residues in many Ca2+ binding proteins, importantly coagulation factors II, VII, IX, and X as well as protein C and protein S

51
Q

What are the important functions of Vitamin E

A

antioxidant in the lipid phase protect membrane lipids from peroxidation

52
Q

What are other names for vitamin E?

A

α-tocopherol

53
Q

1-α hydroxylase important final rate limiting step in conversion of what substrate to what product?

A

vitamin D to 1,25-DHCC (dihydroxycholecalciferol or calcitriol)

54
Q

What are other sources with which to get vit. D if there is insufficient exposure to UV light?

A

Vit. D3 is found in saltwater fish (salmon) and egg yolks

55
Q

Describe or draw out the Steps in the synthesis and activation of vitamin D

A

Draw and explain diagram

56
Q

Genetic deficiencies or patients with end stage renal disease have impaired 1α hydroxylation defects patient must be given 1,25-DHCC. List some of these types of patients.

A

End-stage renal disease secondary to DM

Fanconi renal syndrome (renal proximal tubule defect)

Genetic deficiency of the 1α hydroxylase (vit D resistant rickets)

57
Q

What can excess vit D cause?

A

can promote intestinal absorption of Ca2+ and phosphate also bone resorption leading to hypercalcemia

58
Q

What are some early signs of Vit D toxicity besides bone related conditions?

A

polyuria, polydipsia, and nocturia

59
Q

What does deficiency of vit. D after epiphyseal fusion lead to?

A

osteomalacia

60
Q

Vitamin A is associated with what two important functions?

A

maintenance of healthy epithelium and vision

61
Q

Describe the structures of retinol, retinoic acid, and retinal?

A

retinol has a hydroxyl group at C-1
retinoic acid: a carboxyl group at C-1
retinal: an aldehyde group at C-1 retinal:

62
Q

What are the main functions of retinol and retinoic acid?

A

required for the growth, differentiation, and maintenance of epithelial cells

63
Q

What is a major use for isotretinoin? Which form of vit A is it?

A

a form of retinoic acid that is used in the treatment of acne

64
Q

What are some major teratogenic effects of using isotretinoin?

A

malformations of the craniofacial, cardiac, thymic, and CNS structures)

Kaplan: Biochemistry Part I (27 decks)

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