Vitamins Flashcards

1
Q

put simply, why are vitamins important ?

A

vitamins are important because they act as co-enzymes and co-factors in biological reactions

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2
Q

state what it is meant by the key term - co-factors

A

a non-protein chemical compound or metallic ion that its required for an enzymes activity as a catalyst, but are not used in the reaction

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3
Q

state what it is meant by the key term - co-enzymes

A

a substance that enhances the action of an enzyme as it binds to protein molecules, but are not used in the reaction

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4
Q

state what it is meant by the key term - prosthetic group

A

a prosthetic group is a non-protein chemical group bound to a protein, usually forming part of an active site, and is essential for biological activity

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5
Q

state the names of the 4 fat soluble vitamins

A
  1. retinol (vitamin A)
  2. ergocalciferol (vitamin D)
  3. alpha tocopherol (vitamin E)
  4. phytonadione (vitamin K)
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6
Q

state the names of the 6 B vitamins you need to know

A
  1. Thiamine (B1)
  2. Riboflavin (B2)
  3. Nicotinic acid (B3)
  4. Pantothenic acid (B5)
  5. Pyridoxine (B6)
  6. Cobalamin (B12)
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7
Q

state the names of the 3 other water soluble vitamins you need to know (not including any B group vitamins)

A
  1. Ascorbic acid (C)
  2. Choline
  3. Folates
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8
Q

state 3 sources of Thiamine (B1)

A
  1. liver
  2. fresh vegetables
  3. husk of cereal grains
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9
Q

state the function of Thiamine (B1)

A

Thiamine is required as a co-factor in oxidative decarboxylation reactions (eg - important for ATP resynthesis)

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10
Q

state an example of Thiamine in an oxidative decarboxylation reaction, and state the name of the enzyme which catalyses the reaction

A
  1. Pyruvate + CoASH + NAD+ –> Acetyl CoA + CO2 + NADH

2. pyruvate dehydrogenase (enzyme)

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11
Q

state 3 general facts about the ‘pyruvate dehydrogenase’ enzyme

A
  1. located in the mitochondria
  2. links glycolysis and the CTA/Kreb’s cycle
  3. a multi-enzyme complex comprised of 3 sub-units
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12
Q

pyruvate dehydrogenase is a multi-enzyme complex compromised of what 3 sub-units ?

A
  1. pyruvate dehydrogenase (E1)
  2. dihydrolipoyl transacetylase (E2)
  3. dihydrolipoyl dehydrogenase (E3)
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13
Q

what is the co-factor for the part of the ‘pyruvate dehydrogenase’ sub-unit - pyruvate dehydrogenase (E1)

A

Thiamine pyrophosphate

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14
Q

what is the co-factor for the part of the ‘pyruvate dehydrogenase’ sub-unit - dihydrolipoyl transacetylase (E2)

A

Lipoate, CoA

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15
Q

what is the co-factor for the part of the ‘pyruvate dehydrogenase’ sub-unit - dihydrolipoyl dehydrogenase (E3)

A

FAD, NAD+

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16
Q

state the term for Thiamine (B1) deficiency

A

Beriberi

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17
Q

what type of tissue does Beriberi effect ?

A

Beriberi effects tissue with high ATP turnover (eg - muscle, brain)

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18
Q

state 3/5 symptoms of Beriberi

A
  1. parasthesia (pins + needles)
  2. enlarged heart
  3. wrist and foot drop (inability to turn wrist of foot upward)
  4. muscle weakness + atrophy
  5. digestive disturbances
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19
Q

Beriberi can occur in what two situations ?

A
  1. alcoholics (with a poor diet)

2. communities subsisting on polished rice (removal of the husk = removal of Thiamine/B1)

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20
Q

state, and explain, the two types of Beriberi

A
  1. wet (characterised by oedema and eventual heart failure)

2. dry (neuropathies - any disease of peripheral nerves causing weakness and numbness)

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21
Q

what is a disease which is caused by ‘Neuropathies’ ?

A

Wernicke’s Encephalopathy

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22
Q

state what it is meant by the key term - ‘Neuropathies’

A

Peripheral neuropathy is a type of nerve damage that can cause pain, numbness or weakness

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23
Q

state what 3 things Neuropathies (Wernicke’s Encephalopathy) is characterised by

A
  1. Nystagmus - rapid involuntary eye movements
  2. ophthalmoplegia - paralysis of eye muscles
  3. ataxia - unsteady gait / shaky movements
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24
Q

state what it is meant by the key term - Korsakoff’s syndrome

A

Korsakoff syndrome is a chronic memory disorder caused by severe deficiency of Thiamine (B1)

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25
state what 2 things 'Korsakoff's syndrome' is characterised by
1. amnesia | 2. additional psychiatric manifestations
26
state 4 sources of Nicotinic acid / Niacin (B3)
1. liver 2. legumes 3. lean meats 4. cereals
27
state the reaction that Nicotinic acid (Niacin/B3) takes place in, and the enzyme that catalyses the reaction
1. pyruvate + NADH --> lactate + NAD+ | 2. lactate dehydrogenase
28
what is the term for a deficiency in Nicotinic acid (Niacin/B3)
Pellagra (Italian for 'rough skin')
29
where is pellagra an endemic ?
pellagra is an epidemic in remote areas (ie - where green veg, fruit and animal protein is difficult to obtain)
30
how can Pellagra be avoided in Mexico ?
1. nixtamalization | 2. washing maize with limewater (alkaline) turns bound niacin into unbound niacin
31
state the 4 characteristics of Pellagra (4 D's)
1. dermatitis 2. diarrhoea 3. dementia 4. death (rare)
32
what was Pellagra thought to be caused by, and how was it proven ?
Pellagra was thought to be due to an infection. However, Goldberger showed that it was not. he injected blood from Pellagra patients into 'volunteers' and made them was faeces
33
state what it is meant by the key term - dermatitis
dermatitis is an inflammatory condition of the skin caused by an outside agent
34
what is dermatitis proposed to be caused by ?
proposed to be caused by a decrease in the production of UROCANIC ACID (produced in the body and acts as sunblock)
35
state 4 symptoms of dermatitis
1. boot 2. perineal lesions 3. butterfly rash 4. photosensitive eruptions
36
what is the source of Cobalamin (3 points)
1. not found in plants 2. sole source in nature by micro-organisms 3. dietary source: meat, shellfish, fish and poultry
37
what does absorption of Cobalamin (B12) require ?
gastric intrinsic factor (GIF)
38
what is GIF produced by ?
GIF is produced by the parietal cells of the stomach
39
what is GIF ?
GIF is a glycoprotein with a molecular weight of approx. 50,000
40
what is needed for GIF and Cobalamin (B12) to bind, and where does this binding occur ?
1. 2 molecules of GIF to bind to 2 molecules of Cobalamin (B12) 2. binding occurs in the stomach
41
state, in 3 steps, the absorption process of Cobalamin (B12)
1. binds to brush border of absorption cells (enterocytes) 2. goes into portal venous blood (portal vein transporting absorbed nutrients to the liver) 3. binds to transcobalamin 1, 2, or 3 (transporter protein for cobalamin)
42
state 2 facts about deficiency of Cobalamin (B12)
1. rare as only low concentrations are required | 2. normal healthy adults can survive > 10 years without dietary Cobalamin (B12) without obvious symptoms
43
state the 3 causes of defective absorption of Cobalamin (B12)
1. achlorhydria (absence of HCl in stomach, so no hydrolysis of Cobalamin from food) 2. deficiency in GIF 3. intestinal disease (eg - sprue)
44
state what it is meant by the key term - sprue
deficient absorption of food due to disease of the small intestine
45
sprue is characterised by what 5 things ?
1. diarrhoea 2. weight loss 3. inflamed tongue (glossitis) 4. . anaemia 5. infections
46
state, and briefly explain, another example of an intestinal disease
1. coeliac disease | 2. gluten intolerance, auto immune disease, involves the production of antibodies
47
state the names of the two Cobalamin (B12) deficiency symptoms
1. megaloblastic anaemia | 2. neurological disorders (eg - parasthesia - pins + needles)
48
state 4 symptoms of anaemia
1. excessive fatigue 2. breathlessness 3. fatigue 4. pallor (pale skin)
49
explain what it is meant by the term 'pernicious anaemia'
anaemias resulting from B12 deficiency are referred to as 'pernicious anaemia' as they do not respond to treatment with iron
50
why is anaemia in Cobalamin (B12) deficiency referred to as 'megaloblastic anaemia' ?
due to the fact that there is abnormally large amounts of megaloblasts found in the blood of patients
51
briefly explain what megaloblasts are (2 points)
1. megaloblasts are large, nucleated, immature progenitor cells 2. megaloblast --> erythroblasts --> erythrocytes (for example)
52
both anaemia and neurological symptoms in Cobalamin (B12) deficiency are due to what ?
a last of the amino acid - 'Methionine'
53
what is Cobalamin used for ?
Cobalamin is a co-factor for the enzyme 'methionine Synthase'
54
what is the major issue with a lack of the amino acid 'Methionine' in Cobalamin (B12) deficiency ? (2 points)
1. the first amino acid produced during translation of a protein 2. required in tissue with a high turnover rate
55
what is the major issue with a lack of the amino acid 'Methionine' in neurological symptoms of Cobalamin (B12) deficiency ?
1. Methionine acts as a methyl donor for phosphatidylcholine, and therefore, choline production 2. choline it required for acetyl choline production and sphingomyelin, and therefore, myelin
56
state, and briefly explain, the two forms of Vitamin A
1. Retinol - found mainly in liver and eggs. can be converted into retinoic acid 2. Retinal - provitamin of vitamin A. can be converted into Retinol. found mainly in carrots and spinach
57
what are the main functions of Vitamin A ? (3 points)
1. Vitamin A is required for the production of the visual pigment 'Rhodopsin' (used in low light levels) 2. required for normal brain development 3. both high and low levels may result in brain malfunction
58
state what it is meant by the key term - Teratogen
Teratogen - any substance that induces formation or developmental abnormalities
59
state the names of 2 examples of Teratogens
1. Alcohol (mechanism unknown) | 2. Thalidomide
60
what is 'Alcohol Teratogen' characterised by ?
characterised by growth retardation, behavioural and learning difficulties, and minor facial abnormalities
61
state 5 examples of facial abnormalities
1. flat bridge across nose 2. flat philtrum 3. upturned nose 4. thin upper lip
62
explain how 'Thalidomide Teratogen' works (2 points)
1. prescribed either as a antiemetic (for morning sickness) or as a sleeping tablet 2. results in PHOCOMELIA (shortening, or absence, of upper bone in a limb)
63
where does the term 'Beriberi' (Thiamine/B1 deficiency) come from ?
Sinhalese for 'extreme weakness'
64
what is the actual name for Vitamin A ?
retinol
65
what is the actual name for Vitamin B ?
ergocalciferol
66
what is the actual name for Vitamin C ?
alpha tocopherol
67
what is the actual name for Vitamin D ?
phytonadione
68
what is the actual name for Vitamin B1 ?
Thiamine (B1)
69
what is the actual name for Vitamin B2 ?
Riboflavin (B2)
70
what is the actual name for Vitamin B3 ?
Nicotinic acid (B3)
71
what is the actual name for Vitamin B5 ?
Pantothenic acid (B5)
72
what is the actual name for Vitamin B6 ?
Pyridoxine (B6)
73
what is the actual name for Vitamin B12 ?
Cobalamin (B12)
74
what is the actual name for Vitamin C ?
ascorbic acid