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Biochemistry 2 Final Exam > Vitamins and Minerals > Flashcards

Vitamins and Minerals Flashcards

1
Q

What is the difference between vitamins and minerals?

A

vitamins are organic compounds, minerals are inorganic

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2
Q

What are some macrominerals?

A

Mg, Ca, Na, K, P, Cl

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3
Q

What are some microminerals?

A

Mn, Fe, Cu, Zn, Ni

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4
Q

What are the majority of vitamin/mineral functions?

A

vitamins as coenzymes, minerals as cofactors

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5
Q

What are some water-soluble vitamins? (9)

A

thiamin, riboflavin, niacin, pantothenic acid, biotin, pyridoxine, folate, Vitamin C

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6
Q

What are some fat-soluble vitamins? (4)

A

Vitamins A,D,E,K

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7
Q

Name seven causes of a vitamin deficiency

A
  1. inadequate intake; 2. inadequate absorption; 3. inadequate use; 4. inadequate requirements (pregnancy, eg); 5. increased excretion; 6. loss of microbial synthesis; 7. drug-induced
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8
Q

What is the active form of thiamine?

A

Thiamine pyrophosphate

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9
Q

Can thiamine be supplied from intestinal bacteria?

A

not significantly

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10
Q

How long do liver stores of thiamine generally last?

A

2 weeks

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11
Q

What are four enzymes that use thiamine pyrophosphate and what pathways are they in?

A

pyruvate dehydrogenase (pyruvate oxidation); a-keto glutarate dehydrogenase (Krebs-cycle); BCAA dehydrogenase, transketolase (pentose pathway)

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12
Q

How does a thiamine (B1) deficiency lead to Wiernicke-Korsakoff syndrome?

A

thiamine pyrophosphate is required for transketolase, and enzyme in the pentose pathway.

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13
Q

What is vitamin B2?

A

riboflavin

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14
Q

Can riboflavin be supplied from intestinal bacteria?

A

in limited amounts

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15
Q

Where is riboflavin made?

A

FMN is made in intestinal mucosa, FAD is made in the liver

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16
Q

What is a function of riboflavin?

A

a coenzyme in redox reactions

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17
Q

Why might a riboflavin deficiency be seen in infants who undergo phototherapy for jaundice?

A

riboflavin breaks down on exposure to visible light

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18
Q

What are two metabolic processes that require riboflavin?

A

succinate –> fumarate in Krebs cycle. ETC complex 1, pyruvate dehydrogenase, a-keto glutarate dehydrogenase

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19
Q

What amino acid can be converted into niacin?

A

tryptophan

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20
Q

How many steps in the conversion of glucose-6-phosphate to CO2 require NAD?

A

about 3

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21
Q

Corn based diets are assoicated with niacin deficiency (pellagra). Native people prepared maize with ashes and did not have niacin deficiency- Explain

A

lyme alkalizes the corn, releasing the niacin

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22
Q

What is vitamin B3?

A

niacin

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23
Q

What is vitamin B5?

A

Pantothenic acid, a constituent of CoA

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24
Q

Is B5 synthesized by intestinal bacteria?

A

yes, some

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25
Q

Which of these metabolic processes does not use CoA? cholesterol biosynthesis, Krebs Cycle, pyruvate oxidation, glycolysis, FA synthesis, FA degradation?

A

glycolysis

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26
Q

What vitamin is B6?

A

pyridoxal phosphate

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27
Q

Where is B6 absorbed?

A

upper GI

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28
Q

What is a major breakdown product of Vitamin B6

A

pyridoxic acid, formed in the liver

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29
Q

Pyridoxal phosphate is a coenzyme for what four types of reactions?

A

transaminations, decarboxylations, deaminations, racemizations

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30
Q

What vitamin is a coenzyme for glycogen phosphorylase?

A

Vitamin B6 (pyridoxal phosphate)

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31
Q

What is the connection of B6 to sideroblastic anemia?

A

B6 required for d-ALA synthase, in the first step of heme synthesis. Thus, iron is present but no hemoglobin is made.

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32
Q

What is a connection of B6 deficiency to neurological problems?

A

B6 is required to convert dopa to dopamine

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33
Q

What is vitamin B7?

A

Biotin

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34
Q

Is biotin made by intestinal bacteria?

A

yes

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35
Q

What is a function of biotin?

A

a coenzyme in carboxylation enzymes?

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36
Q

Why can large amount of egg-white intake lead to a biotin deficiency?

A

Avidin, a protein in egg-white can bind up B7

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37
Q

Why is propionic anemia seen in biotin deficiency?

A

no oxidation of odd-chain FAs

38
Q

What by-pass reaction in gluconeogenesis would be affected in a vitamine B7 (biotin) deficiency?

A

the first bypass reaction- pyruvate carboxylation to oxaloacetate- pyruvate carboxylase

39
Q

What is vitamin B9?

A

Folic Acid

40
Q

What are the three components of folic acid?

A

pteridine ring, glutamate, p-aminobenzoate

41
Q

What vitamin is easily destroyed by cooking?

A

Vitamin B9- Folic acid

42
Q

how long do body stores of folic acid generally last?

A

4-6 months

43
Q

in what form does folic acid exist in the cells? in food?

A

polyglutamate form

44
Q

How is a megaloblastic anemia precipitated by pregnancy on marginally folate-deficient diets?

A

aka macrocytic anemia. RBCs cant divide- there’s not enough THF to make new DNA, so RBCs just continue to grow

45
Q

What is vitamin B12?

A

cobalamin

46
Q

cobalamin is a type of

A

coronoid

47
Q

What are five types of cobalamin?

A

methyl, cyano, aqua, hydroxo, deoxyadenosyl

48
Q

What are some types of cobalamin derivatives?

A

change saturation, metal, metal oxidation state

49
Q

What is the problem with cobalamin derivatives?

A

we cant use them

50
Q

How is B12 absorbed? Why can overdosing work in deficiencies?

A

with intrinic factor in the ileum. 1% can also pass via diffusion

51
Q

How is B12 transported in the serum?

A

via transcobalamin or albumin

52
Q

In what three tissues are B12 activated?

A

liver, bone marrow, reticulocytes

53
Q

What two reactions require B12?

A

use of propionyl CoA and methylation of homocyteine

54
Q

What causes pernicious anemia?

A

B12 deficienc due to absence of intrinsic factor

55
Q

Do bacteria produce B12?

A

yes, thats why fermented foods are high in B12

56
Q

Where is B12 stored and how long do those stores last?

A

liver, goes to bile and is reabsorbed. Thus, stores can last for years

57
Q

How does damage to the ileum lead to anemia?

A

cant absorb B12, so can’t methylate homocysteine, thus THF cant function and nucleotides cant be made, so no RBC division

58
Q

What is Vitamin C used for?

A

hydroxylation of proline and lysine; synthesis of norepi/epi; an antioxidant; aids Fe absorption, in conversion of cholesterol to bile acids

59
Q

Which of the functions of Vitamin C contributes to the lethargy and fatigue associated with scurvy?

A

low Fe (?)

60
Q

What are the 3 active forms of Vitamin A?

A

retinal, retinol, retinoic acid

61
Q

where is 90% of vitamin A stored?

A

liver (stellate ITO cells)

62
Q

What is a precursor for retinol?

A

b-carotenoids

63
Q

What enzyme breaks down carotenoid to retinal?

A

dioxygenase, a brush-border enzyme

64
Q

What is the storage form of vitamin A?

A

retinol esters

65
Q

What is a primary use of vitamin A?

A

absorption of light

66
Q

Why is it OK to have a high dose of Vitamin A?

A

dioxygenase is inefficient and often cleaves carotenoids in odd places, leaving smaller chains unusable

67
Q

What protein complexes with Vitamin A during transport?

A

Retinol binding protein (RBP)

68
Q

What is significant about thyroid hormone and Vitamin A?

A

binding to thyroid hormone in circulation helps vitamin A and RBP avoid loss in GFR. thyroid hormone also often binds receptors with vitamin A, thus Vitamin A helps with thyroid hormone signalling

69
Q

about how many genes does vitamin A affect?

A

up to 500

70
Q

What is the first step in vitamin D activation?

A

7-dehydrocholesterol –>cholecalciferol in the skin due to UV light (t1/2=36-72 hours)

71
Q

What is the second step in Vitamin D activation?

A

cholecalciferol –>25-hydroxycholecalciferol in the liver (t1/2= 15 days) (CYP27A)

72
Q

What is the third step in Vitamin D activation?

A

25-hydroxycholecalciferol –> 1,25 dihydroxycholecalciferol in the kidney (t1/2=4-15 hours) (in response to PTH) (CYP27B)

73
Q

How many OH groups does 1,25-dihydroxycholecalciferol have?

A

3

74
Q

About how many genes are targeted by vitamin D?

A

200-3,000

75
Q

what is required for Vitamin D absorption from the GI tract?

A

bile

76
Q

What type of compound is Vit E?

A

tocopherol

77
Q

What does Vit E do?

A

prevent free radical formation in PUFAs

78
Q

What type of compound is Vit K?

A

menaquinones

79
Q

Which comes from bacteria, which from plants? Vit K1 or K2? Are they saturated or unsaturated?

A

K1 comes from bacteria and is unsaturated. K2 comes from plants and is saturated

80
Q

What is the main known function of Vit K?

A

carboxylation of blood clotting factors.

81
Q

What two enzymes if manganese found in?

A

pyruvate carboxylase, mitochondrial SOD

82
Q

What is molybdenum found in?

A

xanthine oxidase

83
Q

What enzyme is selenium found in?

A

glutathione peroxidase

84
Q

What enzymes are Zn found in?

A

Carbonic anhydrase, cytosolic SOD, carboxypeptidase

85
Q

What enzymes is Cu found in?

A

Cytochrome oxidase, ceruloplasmin, Dopamine b-hydroylase, tyrosinase, cytosolic SOD

86
Q

What enzymes is Fe found in?

A

hemoglobin, cytochromes, ETC, catalase, transferrin, ferritin,

87
Q

What is cobalt found in?

A

Vitamin B12- cobalamin

88
Q

What is chromium found in?

A

glucose tolerance factor

89
Q

What is sulfur found in?

A

amino acids, glutathione, CoA, Lipoic acid,

90
Q

What is iodine in?

A

thyroid hormones

Biochemistry 2 Final Exam (5 decks)

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