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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
Which of these metabolic processes does not use CoA? cholesterol biosynthesis, Krebs Cycle, pyruvate oxidation, glycolysis, FA synthesis, FA degradation?
glycolysis
26
What vitamin is B6?
pyridoxal phosphate
27
Where is B6 absorbed?
upper GI
28
What is a major breakdown product of Vitamin B6
pyridoxic acid, formed in the liver
29
Pyridoxal phosphate is a coenzyme for what four types of reactions?
transaminations, decarboxylations, deaminations, racemizations
30
What vitamin is a coenzyme for glycogen phosphorylase?
Vitamin B6 (pyridoxal phosphate)
31
What is the connection of B6 to sideroblastic anemia?
B6 required for d-ALA synthase, in the first step of heme synthesis. Thus, iron is present but no hemoglobin is made.
32
What is a connection of B6 deficiency to neurological problems?
B6 is required to convert dopa to dopamine
33
What is vitamin B7?
Biotin
34
Is biotin made by intestinal bacteria?
yes
35
What is a function of biotin?
a coenzyme in carboxylation enzymes?
36
Why can large amount of egg-white intake lead to a biotin deficiency?
Avidin, a protein in egg-white can bind up B7
37
Why is propionic anemia seen in biotin deficiency?
no oxidation of odd-chain FAs
38
What by-pass reaction in gluconeogenesis would be affected in a vitamine B7 (biotin) deficiency?
the first bypass reaction- pyruvate carboxylation to oxaloacetate- pyruvate carboxylase
39
What is vitamin B9?
Folic Acid
40
What are the three components of folic acid?
pteridine ring, glutamate, p-aminobenzoate
41
What vitamin is easily destroyed by cooking?
Vitamin B9- Folic acid
42
how long do body stores of folic acid generally last?
4-6 months
43
in what form does folic acid exist in the cells? in food?
polyglutamate form
44
How is a megaloblastic anemia precipitated by pregnancy on marginally folate-deficient diets?
aka macrocytic anemia. RBCs cant divide- there's not enough THF to make new DNA, so RBCs just continue to grow
45
What is vitamin B12?
cobalamin
46
cobalamin is a type of
coronoid
47
What are five types of cobalamin?
methyl, cyano, aqua, hydroxo, deoxyadenosyl
48
What are some types of cobalamin derivatives?
change saturation, metal, metal oxidation state
49
What is the problem with cobalamin derivatives?
we cant use them
50
How is B12 absorbed? Why can overdosing work in deficiencies?
with intrinic factor in the ileum. 1% can also pass via diffusion
51
How is B12 transported in the serum?
via transcobalamin or albumin
52
In what three tissues are B12 activated?
liver, bone marrow, reticulocytes
53
What two reactions require B12?
use of propionyl CoA and methylation of homocyteine
54
What causes pernicious anemia?
B12 deficienc due to absence of intrinsic factor
55
Do bacteria produce B12?
yes, thats why fermented foods are high in B12
56
Where is B12 stored and how long do those stores last?
liver, goes to bile and is reabsorbed. Thus, stores can last for years
57
How does damage to the ileum lead to anemia?
cant absorb B12, so can't methylate homocysteine, thus THF cant function and nucleotides cant be made, so no RBC division
58
What is Vitamin C used for?
hydroxylation of proline and lysine; synthesis of norepi/epi; an antioxidant; aids Fe absorption, in conversion of cholesterol to bile acids
59
Which of the functions of Vitamin C contributes to the lethargy and fatigue associated with scurvy?
low Fe (?)
60
What are the 3 active forms of Vitamin A?
retinal, retinol, retinoic acid
61
where is 90% of vitamin A stored?
liver (stellate ITO cells)
62
What is a precursor for retinol?
b-carotenoids
63
What enzyme breaks down carotenoid to retinal?
dioxygenase, a brush-border enzyme
64
What is the storage form of vitamin A?
retinol esters
65
What is a primary use of vitamin A?
absorption of light
66
Why is it OK to have a high dose of Vitamin A?
dioxygenase is inefficient and often cleaves carotenoids in odd places, leaving smaller chains unusable
67
What protein complexes with Vitamin A during transport?
Retinol binding protein (RBP)
68
What is significant about thyroid hormone and Vitamin 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
about how many genes does vitamin A affect?
up to 500
70
What is the first step in vitamin D activation?
7-dehydrocholesterol -->cholecalciferol in the skin due to UV light (t1/2=36-72 hours)
71
What is the second step in Vitamin D activation?
cholecalciferol -->25-hydroxycholecalciferol in the liver (t1/2= 15 days) (CYP27A)
72
What is the third step in Vitamin D activation?
25-hydroxycholecalciferol --> 1,25 dihydroxycholecalciferol in the kidney (t1/2=4-15 hours) (in response to PTH) (CYP27B)
73
How many OH groups does 1,25-dihydroxycholecalciferol have?
3
74
About how many genes are targeted by vitamin D?
200-3,000
75
what is required for Vitamin D absorption from the GI tract?
bile
76
What type of compound is Vit E?
tocopherol
77
What does Vit E do?
prevent free radical formation in PUFAs
78
What type of compound is Vit K?
menaquinones
79
Which comes from bacteria, which from plants? Vit K1 or K2? Are they saturated or unsaturated?
K1 comes from bacteria and is unsaturated. K2 comes from plants and is saturated
80
What is the main known function of Vit K?
carboxylation of blood clotting factors.
81
What two enzymes if manganese found in?
pyruvate carboxylase, mitochondrial SOD
82
What is molybdenum found in?
xanthine oxidase
83
What enzyme is selenium found in?
glutathione peroxidase
84
What enzymes are Zn found in?
Carbonic anhydrase, cytosolic SOD, carboxypeptidase
85
What enzymes is Cu found in?
Cytochrome oxidase, ceruloplasmin, Dopamine b-hydroylase, tyrosinase, cytosolic SOD
86
What enzymes is Fe found in?
hemoglobin, cytochromes, ETC, catalase, transferrin, ferritin,
87
What is cobalt found in?
Vitamin B12- cobalamin
88
What is chromium found in?
glucose tolerance factor
89
What is sulfur found in?
amino acids, glutathione, CoA, Lipoic acid,
90
What is iodine in?
thyroid hormones

Biochemistry 2 Final Exam (5 decks)

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