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Flashcards in Biochem - Nutrition Deck (168)
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1
Q

Calcium homeostasis is associated with which fat-soluble vitamin?

A

Vitamin D

2
Q

Clotting factor synthesis depends on which fat-soluble vitamin?

A

Vitamin K

3
Q

Which fat-soluble vitamin acts as an antioxidant?

A

Vitamin E

4
Q

Which groups of vitamins are water soluble?

A

B vitamins and vitamin C

5
Q

Is vitamin C fat soluble or water soluble?

A

Water soluble

6
Q

Is thiamine fat soluble or water soluble?

A

Water soluble

7
Q

Is riboflavin fat soluble or water soluble?

A

Water soluble

8
Q

Is pantothenic acid fat soluble or water soluble?

A

Water soluble

9
Q

Is cobalamin fat soluble or water soluble?

A

Water soluble

10
Q

Are pyridoxine, pyridoxal, and pyridoxamine fat soluble or water soluble?

A

Water soluble

11
Q

Is ascorbic acid fat soluble or water soluble?

A

Water soluble

12
Q

Deficiency of which two water-soluble vitamins can cause macrocytic anemia?

A

Folate and B12

13
Q

Which water-soluble vitamin is associated with collagen synthesis?

A

Vitamin C (ascorbic acid)

14
Q

Name two vitamins that serve as antioxidants.

A

Vitamin E and vitamin C

15
Q

Name the four fat-soluble vitamins.

A

A, D, E, and K

16
Q

True or False? The absorption of fat-soluble vitamins depends on the pancreas as well as the gastrointestinal tract.

A

True; pancreatic lipases are necessary for absorption of fat-soluble vitamins

17
Q

Is accumulation of fat- or water-soluble vitamins more likely to cause toxicity?

A

Fat

18
Q

Name two malabsorption syndromes that can cause fat-soluble vitamin deficiencies.

A

Cystic fibrosis and sprue

19
Q

Are the B-complex vitamins fat soluble or water soluble?

A

Water soluble

20
Q

All of the water-soluble vitamins easily wash out from the body, except for which two?

A

Vitamin B12 and folate

21
Q

In which organ is folate stored?

A

The liver

22
Q

B-complex deficiencies often result in what three conditions?

A

Dermatitis, glossitis, and diarrhea

23
Q

What is another name for vitamin A?

A

Retinol (remember Retinol is Vitamin-A, so think Retin-A)

24
Q

What are the signs and symptoms of vitamin A deficiency?

A

Night blindness and dry skin

25
Q

Vitamin A is a constituent of what visual pigment?

A

Retinal

26
Q

What are the symptoms associated with vitamin A intoxication?

A

Arthralgias, fatigue, headaches, skin changes, sore throat, and alopecia

27
Q

A man has recently been eating large amounts of liver. He presents with fatigue, hair loss, headache, and joint pains. What is your diagnosis?

A

Vitamin A excess

28
Q

What foods contain high amounts of vitamin A?

A

Vitamin A is found in liver, and in leafy vegetables

29
Q

Name two topical uses of vitamin A.

A

It can be used topically for wrinkles and for acne

30
Q

What are the effects of taking large amounts of vitamin A during pregnancy?

A

It is a teratogen, and causes cleft palate and cardiac abnormalities

31
Q

What is another name for vitamin B1?

A

Thiamine

32
Q

Beriberi is caused by a deficiency of which vitamin?

A

Vitamin B1 (thiamine) (spell beriberi as Ber1Ber1)

33
Q

Wernicke-Korsakoff syndrome is caused by a deficiency of which vitamin?

A

Vitamin B1 (thiamine)

34
Q

Vitamin B1 is the precursor to what metabolic cofactor?

A

Thiamine pyrophosphate

35
Q

What is the role of thiamine in the tricarboxylic acid cycle?

A

It is a cofactor for -ketoglutarate dehydrogenase

36
Q

Which step in glycolysis requires thiamine?

A

Thiamine pyrophosphate is needed as a cofactor for pyruvate dehydrogenase

37
Q

What vitamin is needed as a cofactor for branched-chain amino acid dehydrogenase?

A

Vitamin B1 (thiamine)

38
Q

A known alcoholic presents with symptoms of muscle wasting and polyneuritis. What vitamin deficiency do you suspect?

A

Vitamin B1 (thiamine)

39
Q

Are polyneuritis and muscle wasting characteristic of wet or dry beriberi?

A

Dry beriberi; wet beriberi is associated with high-output cardiac failure and edema

40
Q

Why are alcoholics prone to beriberi and Wernicke-Korsakoff syndrome?

A

Malnutrition and malabsorption

41
Q

An alcoholic patient in the emergency room has recent-onset ophthalmoplegia, confusion, and ataxia; you suspect what disease process?

A

Wernicke-Korsakoff syndrome

42
Q

Why are the brain and heart susceptible to injury in thiamine deficiency?

A

Cells cannot generate adenosine triphosphate without thiamine and highly metabolically active cells are damaged first

43
Q

What is another name for vitamin B2?

A

Riboflavin

44
Q

Cheilosis and corneal vascularization occur as a result of a deficiency of which vitamin?

A

Vitamin B2 (riboflavin) (remember: the 2 Cs)

45
Q

What is cheilosis?

A

Inflammation of the lips, with scaling and fissures at the corners of the mouth; this is seen in vitamin B2 deficiency

46
Q

Flavin adenine dinucleotide is derived from which vitamin?

A

Vitamin B2 (riboflavin) (remember: FAD and FMN are derived from riboFlavin, B2 = 2 ATP)

47
Q

What is another name for vitamin B3?

A

Niacin

48
Q

A deficiency of vitamin B3 (niacin) leads to what disease?

A

Pellagra

49
Q

How can Hartnup disease lead to pellagra?

A

Through impaired absorption of tryptophan, which is used to synthesize niacin

50
Q

How can malignant carcinoid syndrome lead to pellagra?

A

Through increased metabolism of tryptophan, which is used to synthesize niacin

51
Q

How does isoniazid cause a niacin deficiency?

A

By depleting vitamin B6, the synthesis of niacin from tryptophan cannot occur

52
Q

A patient being treated for hyperlipidemia complains of becoming red in the face after taking his medication; what drug is he taking?

A

He is likely on niacin, which at pharmacologic doses can cause facial flushing

53
Q

What vitamin is the precursor of oxidized nicotinamide adenine dinucleotide and oxidized nicotinamide adenine dinucleotide phosphate?

A

Vitamin B3 (niacin) (remember: NAD derived from Niacin, B3 = 3 ATP)

54
Q

What are the 3 Ds of pellagra?

A

Diarrhea, Dermatitis, and Dementia

55
Q

True or False? In addition to diarrhea, dermatitis, and dementia, pellagra is also characterized by beefy glossitis.

A

TRUE

56
Q

True or False? Eating excess untreated corn can lead to pellagra.

A

True; vitamin B3 in corn is not absorbable unless treated

57
Q

What is another name for vitamin B5?

A

Pantothenate

58
Q

What are the symptoms of vitamin B5 deficiency?

A

Dermatitis, enteritis, alopecia, and adrenal insufficiency

59
Q

What vitamin is a precursor of coenzyme A, a cofactor for acyl transfer?

A

Vitamin B5 (pantothenate) (remember: pantothen-A is in Co-A)

60
Q

What vitamin is a component of fatty acid synthase?

A

Vitamin B5 (pantothenate)

61
Q

Adrenal insufficiency may be caused by a deficiency of which vitamin?

A

Vitamin B5 (pantothenate)

62
Q

What is another name for vitamin B6?

A

Pyridoxine

63
Q

What are the clinical features of vitamin B6 deficiency?

A

Convulsions, hyperirritability, peripheral neuropathy, and sideroblastic anemias

64
Q

A deficiency of vitamin B6 is inducible by what two drugs?

A

Isoniazid and oral contraceptive pills

65
Q

A 32-year-old man begins taking isoniazid after a positive purified protein derivative. He presents with numbness and tingling in the extremities. What is the most likely cause of his peripheral neuropathy?

A

Vitamin B6 (pyridoxine) deficiency induced by INH

66
Q

Which vitamin is the precursor to pyridoxal phosphate?

A

Vitamin B6 (pyridoxine)

67
Q

Which vitamin is needed for transamination (alanine aminotransferase and aspartate aminotransferase) reactions?

A

Vitamin B6 (pyridoxine)

68
Q

Which vitamin is needed for decarboxylation reactions?

A

Vitamin B6 (pyridoxine)

69
Q

Which vitamin is needed as a cofactor for glycogen phosphorylase?

A

Vitamin B6 (pyridoxine)

70
Q

What vitamin is required for conversion of tryptophan to niacin?

A

Vitamin B6 (pyridoxine)

71
Q

Which vitamin is needed for heme synthesis?

A

Vitamin B6 (pyridoxine)

72
Q

Which vitamin is required for the synthesis of niacin from tryptophan?

A

Vitamin B6 (pyridoxine)

73
Q

What is another name for vitamin B12?

A

Cobalamin

74
Q

What are the hematologic manifestations of vitamin B12 deficiency?

A

Megaloblastic anemia

75
Q

What are the neurologic manifestations of vitamin B12 deficiency?

A

Subacute combined degeneration, paresthesia, and optic neuropathy

76
Q

Which vitamin transfers a methyl group to form methionine from homocysteine?

A

Vitamin B12 (cobalamin)

77
Q

Which vitamin is needed for the conversion of methylmalonyl-CoA to succinyl-CoA?

A

Vitamin B12 (cobalamin)

78
Q

In which organ is vitamin B12 stored?

A

The liver

79
Q

If a person stopped all vitamin B12 intake, how long would it take to develop symptoms of deficiency?

A

Several years

80
Q

What are dietary sources of vitamin B12?

A

Animal products

81
Q

Pernicious anemia can cause vitamin ____ deficiency as a result of a lack of _____ _____.

A

B12; intrinsic factor

82
Q

What medical conditions can lead to vitamin B12 deficiency?

A

Sprue enteritis, Diphyllobothrium latum infection, pernicious anemia, Crohn's disease

83
Q

What test is used to detect the cause of a deficiency of vitamin B12?

A

The Schilling test

84
Q

What is the pathophysiology of the neurologic signs and symptoms of B12 deficiency?

A

Synthesis of abnormal myelin

85
Q

A 42-year-old woman with a history of gastric bypass surgery 5 years ago presents with visual disturbance and numbness in her fingers. She is found to have macrocytic anemia. What is the most likely cause of her symptoms?

A

Vitamin B12 deficiency

86
Q

True or False? The neurologic sequelae of vitamin B12 deficiency are easily reversible with vitamin supplementation.

A

False; a prolonged deficiency of cobalamin leads to irreversible nervous system damage

87
Q

What is the most common vitamin deficiency in the United States?

A

Folic acid deficiency

88
Q

What are the results of folate deficiency?

A

Macrocytic and megaloblastic anemias

89
Q

What is the function of tetrahydrofolate?

A

It is a coenzyme for 1-carbon transfer/methylation reactions

90
Q

What form of folate acts as a metabolic cofactor?

A

Tetrahydrofolate

91
Q

Tetrahydrofolate is necessary for synthesis of what biological molecules?

A

Nitrogenous bases in DNA and RNA

92
Q

True or False? Folic acid stores last for 5 years, so symptoms of depletion take a long time to develop after dietary insufficiency.

A

False; folate is not stored for very long

93
Q

Supplemental folic acid is given during early pregnancy to reduce the incidence of _____ _____ _____.

A

Neural tube defects

94
Q

What are dietary sources of folate?

A

Leafy greens (remember: FOLate from FOLiage)

95
Q

Name 3 drugs that can cause a folic acid deficiency.

A

Methotrexate, phenytoin, sulfonamides

96
Q

Compare and contrast symptoms of B12 and folate deficiency.

A

There are no neurologic symptoms in folate deficiency

97
Q

S-adenosylmethionine is formed from what two precursors?

A

Adenosine triphosphate and methionine

98
Q

The regeneration of methionine and S-adenosylmethionine from homocysteine is dependent on which two vitamins?

A

Vitamin B12 and folate

99
Q

What is the functional group involved in S-adenosylmethionine reactions?

A

S-adenosylmethionine tranfers methyl units (remember: S-adenosylmethionine the methyl donor man)

100
Q

What enzyme uses S-adenosylmethionine to create homocysteine from methionine?

A

Homocysteine methyltransferase

101
Q

S-adenosylmethionine is required to synthesize which neurotransmitter?

A

Epinephrine

102
Q

A deficiency of _____ may be caused by the use of antibiotics or the ingestion of raw eggs.

A

Biotin

103
Q

What are the symptoms of biotin deficiency?

A

Dermatitis, enteritis, and alopecia

104
Q

Biotin is required as a cofactor for _____ reactions.

A

Carboxylation (which add a 1-carbon group)

105
Q

Biotin and pyruvate carboxylase catalyze what reaction?

A

Conversion of pyruvate to oxaloacetate

106
Q

Biotin and acetyl-CoA carboxylase catalyze what reaction?

A

Conversion of acetyl-CoA into malonyl-CoA

107
Q

Biotin and propionyl-CoA carboxylase catalyze what reaction?

A

Conversion of propionyl-CoA to methylmalonyl-CoA

108
Q

What enzyme requires a biotin cofactor to create oxaloacetate?

A

Pyruvate carboxylase

109
Q

What enzyme requires a biotin cofactor to create malonyl-CoA?

A

Acetyl-CoA carboxylase

110
Q

What enzyme requires a biotin cofactor to create methylmalonyl-CoA?

A

Propionyl-CoA carboxylase

111
Q

Biotin is bound by _____, which is found in egg whites.

A

Avidin (remember: AVID in egg whites AVIDly binds biotin)

112
Q

What is another name for vitamin C?

A

Ascorbic acid

113
Q

What disease is caused by a deficiency of vitamin C?

A

Scurvy

114
Q

A patient has swollen gums, bruising, anemia, and poor wound healing. What vitamin deficiency is probably responsible for these symptoms?

A

Vitamin C deficiency

115
Q

List four symptoms that are associated with scurvy.

A

Swollen gums, bruising, anemia, and poor wound healing

116
Q

Vitamin C is needed for the addition of _____ groups to the amino acids lysine and proline during collagen synthesis.

A

Hydroxyl

117
Q

Vitamin C _____ (promotes/inhibits) iron absorption by keeping it in the _____ (reduced/oxidized) state, which is more absorbable.

A

Promotes; reduced

118
Q

True or False? Vitamin C is required for the conversion of dopamine to norepinephrine.

A

TRUE

119
Q

What are dietary sources of vitamin C?

A

Fruits and vegetables; British sailors carried limes to prevent scurvy (origin of the word limey)

120
Q

What function does vitamin C share with vitamin E?

A

Both are antioxidants

121
Q

What enzyme uses ascorbic acid to convert dopamine to norepinephrine?

A

Dopamine -hydroxylase

122
Q

Is vitamin D2 found in plants or produced in sun-exposed skin?

A

Vitamin D2 is found in plants

123
Q

What is another name for vitamin D2?

A

Ergocalciferol

124
Q

What form of vitamin D is found in vitamins and other pharmaceuticals?

A

Vitamin D2

125
Q

Is vitamin D3 found in plants or produced in sun-exposed skin?

A

Vitamin D3 is produced in sun-exposed skin

126
Q

When drinking a glass of milk, what type of vitamin D are you absorbing?

A

Vitamin D3 (remember: drinking milk (fortified with vitamin D) is good for bones)

127
Q

What is another name for vitamin D3?

A

Cholecalciferol

128
Q

What is the storage form of vitamin D?

A

25-OH D3

129
Q

What is the active form of vitamin D3?

A

1,25(OH)2D3 (calcitriol)

130
Q

A deficiency of vitamin D causes what disease in children?

A

Rickets

131
Q

A deficiency of vitamin D causes what disease in adults?

A

Osteomalacia

132
Q

A deficiency of vitamin D may lead to ______ (hypocalcemia/hypercalcemia) and ______ (flaccid paralysis/tetany).

A

Hypocalcemia; tetany

133
Q

Vitamin D increases the absorption of what two ions in the intestine?

A

Calcium and phosphorus

134
Q

What is the effect of vitamin D on your bones?

A

Vitamin D increases bone resorption

135
Q

A patient has hypercalcemia, loss of appetite, and stupor. What vitamin excess is probably responsible for these symptoms?

A

Vitamin D

136
Q

In what disease do epithelioid macrophages convert vitamin D into its active form in excess, leading to hypercalcemia?

A

Sarcoidosis

137
Q

A deficiency of vitamin E leads to the increased fragility of what cell type?

A

Red blood cells

138
Q

What type of anemia is seen in vitamin E deficiency?

A

Hemolytic anemia

139
Q

A patient presents with hemolytic anemia, muscle weakness, and neuropathy; what vitamin deficiency do you suspect?

A

Vitamin E

140
Q

Vitamin K deficiency leads to _____ (increased/decreased/normal) prothrombin time, _____ (increased/decreased/normal) activated partial thromboplastin time, and _____ (increased/decreased/normal) bleeding time.

A

Increased, increased, normal (remember: K for Koagulation)

141
Q

What is the cause of hemorrhagic disease of the newborn? How is it prevented?

A

The neonatal intestine is sterile and therefore cannot synthesize vitamin K; to prevent hemorrhage, all newborns are given a vitamin K injection at birth

142
Q

Vitamin K is required for which anticoagulation factors?

A

Proteins C and S

143
Q

Which clotting factors are dependent on vitamin K?

A

Factors II, VII, IX, and X and proteins C and S

144
Q

What is the source of vitamin K for humans?

A

Vitamin K is synthesized by intestinal bacteria

145
Q

What is the mechanism by which antibiotic use can cause vitamin K deficiency?

A

Destruction of intestinal bacteria, which synthesize vitamin K

146
Q

What drug is a vitamin K antagonist?

A

Warfarin (coumadin)

147
Q

A patient has delayed wound healing, hypogonadism, and decreased axillary, facial, and pubic hair. What nutritional deficiency is likely to be responsible for these symptoms?

A

Zinc deficiency

148
Q

What dietary deficiency can exacerbate alcoholic cirrhosis?

A

Zinc

149
Q

What are the symptoms of zinc deficiency?

A

Delayed wound healing; hypogonadism; decreased adult hair in the axilla, face, and pubic regions; dysgeusia; anosmia

150
Q

What is the importance of zinc fingers?

A

Zinc fingers allow transcription factors and other molecules to interact with DNA

151
Q

What is the limiting reagent in alcohol metabolism?

A

NAD+

152
Q

What enzyme does disulfiram inhibit?

A

Acetaldehyde dehydrogenase

153
Q

A patient taking fomepizole would have a decreased accumulation of _____ because it inhibits _____.

A

Acetaldehyde; alcohol dehydrogenase; fomepizole is used in cases of methanol poisoning

154
Q

Where in the cell is the reaction that is inhibited by fomepizole?

A

Fomepizole blocks the action of alcohol dehydrogenase, which is in the cytosol

155
Q

Where in the cell is the reaction that is inhibited by disulfiram?

A

Disulfiram inhibits acetaldehyde dehydrogenase, which is in the mitochondria

156
Q

What happens to the rate of ethanol metabolism by alcohol dehydrogenase as more ethanol is consumed?

A

There is no change in the rate since this reaction proceeds by zero-order kinetics

157
Q

Ethanol metabolism _____ (increases/decreases) the NADH/NAD+ ratio in the liver, which _____ (promotes/inhibits) gluconeogenesis.

A

Increases; inhibits

158
Q

Ethanol ingestion leads to the increased conversion of pyruvate to _____ and oxaloacetate to _____, because these reactions regenerate NAD+ from NADH.

A

Lactate; malate

159
Q

The high NADH/NAD+ ratio seen after ethanol ingestion is responsible for the shunting of metabolites away from _____ and toward _____ _____ synthesis.

A

Gluconeogenesis; fatty acid

160
Q

Ethanol metabolism ultimately results in _____ as a result of the inhibition of gluconeogenesis, and hepatocellular _____ from increased fatty acid synthesis.

A

Hypoglycemia, steatosis

161
Q

What by-product of ethanol metabolism is responsible for hepatic steatosis?

A

The accumulation of NADH drives pyruvate to lactate and oxaloacetate to malate, resulting in decreased gluconeogenesis and increased fatty acid synthesis

162
Q

Kwashiorkor is the result of a deficiency of _____ in the diet.

A

Protein

163
Q

A malnourished child is also anemic, edematous, and has elevated liver function tests; what is the diagnosis?

A

Kwashiorkor (remember: Kwashiorkor results from a protein-deficient MEAL: Malnutrition, Edema, Anemia, Liver (fatty))

164
Q

What is the clinical picture of a patient with kwashiorkor?

A

Small child with swollen belly

165
Q

Marasmus is the result of a deficiency of _____ in the diet.

A

Calories

166
Q

A child presents with tissue and muscle wasting with loss of subcutaneous fat. Is she more likely to have kwashiorkor or marasmus?

A

Marasmus

167
Q

A malnourished child has significant tissue wasting. Is she more likely to have kwashiorkor or marasmus?

A

Marasmus (remember: Marasmus results in Muscle wasting)

168
Q

Kwashiorkor is a deficiency of _____ that results in skin lesions, anemia, edema, and liver malfunction (fatty change). By contrast, marasmus is a deficiency of _____ that results in tissue wasting.

A

Protein; calories