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Biochem Exam 4 > Vitamins > Flashcards

Vitamins Flashcards

(54 cards)

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1
Q

What are vitamins?

A

Chemically unrelated organic compounds that we cannot synthesize in adequate quantities

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2
Q

What are the vitamins that toxicity is rare, deficiencies can occur quickly and many are coenzyme precursors?

A

9 water-soluble

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3
Q

What are the vitamins that can lead to accumulation of toxic quantities?

A

4 fat-soluble

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4
Q

What are the water soluble vitamins?

A

Ascorbic acid (C) and B complex

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5
Q

What are the fat soluble vitamins?

A 
A (retinol, beta-carotenes)
D (cholecalciferol)
K (phylloquinones, menaquinones)
E (tocopherols)
-must know all names
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6
Q

What are the energy releasing B complex vitamins?

A 
Thiamine (B1)
Riboflavin (B2)
Niacin (B3)
Pantothenic acid (B5)
Biotin (B7)
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7
Q

What are the hematopoietic B complex vitamins?

A 
Folic acid (B9)
Cobalamin (B12)
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8
Q

What are the B6 vitamins?

A

Pyridoxine
Pyridoxal
Pyridoxamine

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9
Q

What is the most common deficiency in US, especially pregnant women/alcoholics?

A

Folic acid (B9)

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10
Q

What is folic acid used to make?

A

Tetrahydrofolate (transfers 1-C groups)

-Synthesis of methionine, purine and thymidine monophosphate

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11
Q

What are nutritional anemias?

A

Lower than normal [Hb] -> reduced ability to transport oxygen

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12
Q

What is microcytic anemia?

A

Size of RBC < normal

  • Caused by lack of iron
  • Most common
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13
Q

What is macrocytic anemia?

A

Size of RBC > normal

-Deficiency in folic acid/B12

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14
Q

Where is cobalamin (B12) found?

A

Liver, red meat, fish, eggs, dairy, fortified cereals

-Not in plants

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15
Q

What does a deficiency in B12 cause?

A

Megaloblastic anemia

  • Can’t make sugar from fat
  • Can’t make methionine
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16
Q

What is special about B12?

A

Corrin ring w/ cobalt at the center

-Looks like heme

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17
Q

What does malabsorption of B12 lead to?

A

Pernicious anemia

-R-protein + intrinsic factor needed for proper absorption

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18
Q

What does vitamin C fx as?

A

Reducing agent

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19
Q

What is vitamin C a coenzyme in?

A

Hydroxylation rxn of prolyl and lysyl residues of collagen

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20
Q

What are key dietary antioxidants?

A

Vitamin C + E + beta-carotene

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21
Q

What does vitamin C deficiency cause?

A

Scurvy

-Deficiency in hydroxylation of collagen -> defective CT

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22
Q

All vitamin B6s are derivatives of what?

23
Q

What is an important role of B6?

Study These Flashcards
A

Pyridoxal phosphate (PLP): active coenzyme in rxns involving AAs

24
Q

What does >500 mg/day intake of B6 cause?

Study These Flashcards
A

Neurologic sx

25
What is the biologically active form of B1?
Thiamine pyrophosphate (TPP) -> energy - Role in PPP - Role in pyruvate -> acetyl CoA (by pyruvate dehydrogenase) - Role in alpha-ketoglutarate -> succinyl CoA (by alpha-ketoglutarate dehydrogenase)
26
What does a B1 deficiency cause?
Decreased production of ATP
27
What is beriberi?
B1 deficiency; in areas where polished rice is major component of diet
28
What is wernicke-korsakoff syndrome?
B1 impaired absorption; chronic alcoholism
29
What are the biologically active coenzyme forms of Niacin (B3)?
Nicotinamide adenine dinucleotide (NAD+) and NADP+ - necessary for ETC, accepts a hydride ion - found in unrefined/enriched grains/cereal, milk, lean meats/liver
30
What does B3 deficiency cause?
Pellagra -> 3Ds: dermatitis, diarrhea, dementia
31
What is B3 useful in treatment of?
Hyperlipoproteinemia
32
What are the biologically active forms of riboflavin (B2)?
FMN and FAD - Reversibly accepts 2 H atoms - Bound tightly to flavoenzymes
33
What is Biotin (B7) a coenzyme in?
Carboxylation rxns (carrier of activated CO2)
34
What is biotin covalently bound to?
Amino group of lysine residues in biotin-dependent enzymes | -Weird because coenzymes are not usually covalently linked
35
Where is biotin?
Widely distributed in food - Very rare you see a deficiency - Large % supplied by intestinal bacteria
36
What is pantothenic acid (B5) component of?
CoA | -Sulfhydryl group (always makes a thiol ester)
37
Where is B5 found in?
Eggs, liver, yeast
38
What is vitamin A (retinoids) related to?
Dietary retinol
39
What is vit A essential for?
Vision, reproduction, growth and maintenance of epithelial tissues
40
What are vit A sources?
Pre-formed: liver, kidney, cream, butter, egg yolk | Precursors: carotenes (yellow, orange, dark green veggies)
41
What does vitamin A dietary deficiency cause?
- Night blindness (early sign) | - Prolonged defic -> irreversible loss in # visual cells
42
How many children worldwide are blinded due to vit A defic?
>500,000
43
What are vit A actions as therapeutic agents?
Tx of skin aging/mild-severe acne/psoriasis, tx of acute promyelocytic leukemia
44
What are vit A actions as dietary components?
Maintenance of reproduction/vision, promotion of growth, differentiation/maintenance of epithelial tissue; gene expression
45
What is vitamin D?
Group of sterols that have hormone-like fx
46
What is the active molecule of vitamin d?
1,25-dihydroxycholecalciferol (calcitriol) | -Binds intracellular receptors
47
What does vit D regulate the plasma levels of?
Calcium + phosphorous
48
What does deficiency of vitamin D cause?
Demineralization of bone -> rickets (children) ; osteomalacia (adults)
49
What do high doses of vit D cause?
Loss of appetite, nausea, thirst, stuppor | -> deposition of Ca2+ in arteries/kidneys
50
What is vitamin K a coenzyme in?
Gamma-carboxylation of certain glutamic acid residues | -Necessary for blood clotting
51
Where is vitamin K found?
Cabbage, kale, spinach, egg yolk, liver, synthesis by bacteria in gut
52
What does vitamin E do?
Main role in antioxidant
53
What is the most active form of E?
alpha-tocopherol
54
Why is vitamin E important to get in your diet?
Least toxic of fat-soluble vitamins

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