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Vitamin c Flashcards

(80 cards)

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1
Q

What type of vitamin is Vitamin C?

A

Water soluble

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2
Q

What is Vitamin C’s role in health and disease?

A

Important

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3
Q

Why is Vitamin C controversial?

A

Claims of curing diseases in megadoses

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4
Q

What diseases has Vitamin C been claimed to cure?

A

Common cold to cancer

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5
Q

What is the first known disease associated with diet?

A

Scurvy

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6
Q

When was scurvy prevalent among mariners?

A

Sixteenth century

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7
Q

How many mariners died from scurvy in the 16th century?

A

About 10,000

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8
Q

What caused scurvy among mariners?

A

Lack of fresh vegetables

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9
Q

Who published ëTreatise on Scurvyí?

A

James Lind

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10
Q

What year was ëTreatise on Scurvyí published?

A

1753

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11
Q

What did the Royal Navy start doing in 1795?

A

Supplying lime or lemon juice to crews

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12
Q

What nickname did English sailors get from carrying lemons?

A

Limeys

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13
Q

What type of compound is ascorbic acid?

A

Hexose derivative

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14
Q

What structure does ascorbic acid resemble?

A

Monosaccharides

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15
Q

What causes the acidity of vitamin C?

A

Enolic hydroxyl groups

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16
Q

What is vitamin Cís chemical property?

A

Strong reducing agent

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17
Q

What is formed by oxidation of L-ascorbic acid?

A

Dehydroascorbic acid

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18
Q

Is the reaction between ascorbic acid and dehydroascorbic acid reversible?

A

Yes

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19
Q

Which forms of vitamin C are biologically active?

A

Ascorbic acid and dehydroascorbic acid

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20
Q

Which form of ascorbic acid is inactive?

A

D-ascorbic acid

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21
Q

What form predominates in plasma and tissues?

A

Reduced form (ascorbic acid)

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22
Q

What is the ratio of ascorbic acid to dehydroascorbic acid in tissues?

A

0.6256944444444446

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23
Q

What is formed when dehydroascorbic acid is hydrated?

A

2,3-diketogulonic acid

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24
Q

Is 2,3-diketogulonic acid active?

A

No

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25
What promotes spontaneous hydration of dehydroascorbic acid?
Alkaline or neutral solution
26
What does hydration of dehydroascorbic acid lead to?
Biological inactivation
27
What accelerates oxidation of ascorbic acid?
Copper
28
What makes vitamin C inactive during cooking?
Use of copper vessels
29
Can all animals synthesize vitamin C?
No
30
What pathway is used for ascorbic acid synthesis in animals?
Uronic acid pathway
31
Which species cannot synthesize ascorbic acid?
Primates, guinea pigs, bats
32
What enzyme deficiency prevents vitamin C synthesis?
L-gulonolactone oxidase
33
Where is vitamin C absorbed?
Intestine
34
Is vitamin C stored significantly in the body?
No
35
How is ascorbic acid excreted?
In urine
36
Name two metabolites of ascorbic acid
Diketogulonic acid
37
What property enables most functions of vitamin C?
Reversible oxidation-reduction
38
What is vitamin C's role in collagen formation?
Coenzyme in hydroxylation of proline and lysine
39
What enzymes require vitamin C for hydroxylation?
Lysyl hydroxylase
40
What are needed for collagen hydroxylation?
Vitamin C
41
What do hydroxyproline and hydroxylysine help with?
Collagen cross-linking
42
What is vitamin C essential for in tissue repair?
Connective tissue maintenance
43
What are the components of bone tissue?
Organic collagen
44
What is vitamin Cís role in bones?
Required for bone formation
45
How does vitamin C aid iron absorption?
Keeps iron in ferrous form
46
What does vitamin C help form from iron?
Ferritin
47
How does vitamin C affect hemoglobin?
Converts methemoglobin to hemoglobin
48
What process in hemoglobin breakdown needs vitamin C?
Formation of bile pigments
49
What amino acid metabolism needs vitamin C?
Tryptophan
50
What is vitamin Cís role in serotonin synthesis?
Hydroxylation of tryptophan
51
What other amino acid needs vitamin C in its metabolism?
Tyrosine
52
What reaction in tyrosine metabolism needs vitamin C?
Oxidation of p-hydroxy phenylpyruvate
53
What is the product of the reaction in tyrosine metabolism?
Homogentisic acid
54
What vitaminís active form needs vitamin C?
Folic acid (tetrahydrofolate)
55
What enzyme uses vitamin C in folate activation?
Folic acid reductase
56
What cells mature with help of ascorbic acid and folate?
Erythrocytes
57
What enzyme in peptide hormone synthesis needs vitamin C?
Peptidylglycine hydroxylase
58
What is hydroxylated in peptide hormone synthesis?
Terminal glycine
59
What gland has high vitamin C levels during stress?
Adrenal gland
60
What hormone synthesis requires vitamin C?
Corticosteroids
61
How does vitamin C spare other vitamins?
Acts as an antioxidant
62
Which vitamins are spared by ascorbic acid?
Vitamin A
63
How does vitamin C support immunity?
Enhances immunoglobulin synthesis
64
What eye condition does vitamin C help prevent?
Cataract
65
What chronic diseases may vitamin C help prevent?
Cancer
66
What is the adult RDA for vitamin C?
60-70 mg/day
67
How much more vitamin C is needed in pregnancy or lactation?
20-40% increase
68
Name four good dietary sources of vitamin C
Citrus fruits
69
Name three more vitamin C-rich foods
Tomatoes
70
Where is high vitamin C content found in the body?
Adrenal gland
71
Is milk a good source of vitamin C?
No
72
What disease results from vitamin C deficiency?
Scurvy
73
Name a gum symptom of scurvy
Spongy
74
What oral issue occurs in scurvy?
Loose teeth
75
What systemic symptoms are seen in scurvy?
Anemia
76
What functions are impaired in scurvy?
Immunity
77
What scientist promoted vitamin C megadoses?
Linus Pauling
78
What dose did Pauling suggest?
Up to 18 g/day
79
What is the effect of megadoses on common cold?
Reduce duration
80
What risk is associated with high vitamin C metabolism?
Kidney stones (from oxalate)

Biochemistry (11 decks)

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