Vitamins, coenzymes and minerals - vitamin A and vision, physiological roles of vitamins, coenzyme forms of vitamins, trace & macrominerals.

1. 7. SOME IMPORTANT QUESTION - ANSWER FOR IGNOU BIOCHEMISTRY [CHE 9]
VITAMINS, COENZYMES AND MINERALS
Q1. Name the diseases associated with deficiency of the following vitamins.[इन विटामिन्स
की कमी से होने वाली बीमारिओं क
े नाम लिखें ]:
Vitamin B1, Riboflavin, Niacin, Vitamin B6, Folic acid, Vitamin B12, Vitamin C, Vitamin D
and Vitamin A.
Ans.
Vitamin B1: Beri-beri in humans and polyneuritis in animals
Riboflavin (B2) - ariboflavinosis
Niacin: Pellagra in humans
Vitamin B6: Dermatitis in rats and convulsions, chronic anemia and peripheral neuropathy in
humans
Folic acid: anemia
Vitamin B12: pernicious anemia
Vitamin C: scurvy
Vitamin A: Xerophthalmia and night blindness
Vitamin D: rickets
Q.2. Write the relationship between vitamin A and vision. Explain visual cycle in the rod
cells.[विटामिन A और vision क
े बीच क्या रिश्ता है I Rod cells में होने वाली visual cycle की व्याख्या करें
I]
Ans. Vitamin A is required for the maintenance of normal vision. A deficiency in vitamin A can
lead to visual disturbances. In the eyes, a form of vitamin A called retinal is combined with a
protein called opsin to give rhodopsin, an essential light absorbing molecule needed for color
vision and seeing in dim light. Vitamin A deficiency leads to Xerophthalmia, a disease that
causes dry eyes and if it is not treated, it can cause night blindness.
Visual cycle of rod cells -
The retina of eyes has two types of photoreceptor cells namely rod cells and cone cells which
are responsible for vision in low light intensity and bright light intensity respectively.The rod cells
contain light absorbing conjugated protein called rhodopsin, made up of protein opsin firmly
bound to an aldehyde of vitamin A, 11-cis-retinal. The visual cycle begins in response to light
which isomerises the bound 11-cis-retinal into all-trans-retinal. This all-trans-retinal dissociates
from rhodopsin and nerve impulse is triggered in retina for vision as light is perceived by the
brain. For reconstitution of rhodopsin, all-trans-retinal is enzymatically reduced to all trans-
vitamin A in presence of NADH. The all-trans-vitamin A isomerises to 11-cis-vitamin A which in
turn oxidised to 11-cis-retinal in presence of NAD+. Finally, 11-cis-retinal combines with opsin to
regenerate rhodopsin to complete the visual cycle. The regenerated rhodopsin participates in
next visual cycle.
1

2. [Vitamin A सामान्य दृष्टि (vision) को बनाए रखने हेतु आवश्यक होता है I शरीर में इसकी कमी होने से
दृश्यात्मक बाधायें आ सकती हैं I आँखों में vitamin A का एक रूप, जिसे retinal कहते हैं, opsin नामक एक
protein से जुड़कर rhodopsin नामक दृष्टि क
े लिए अनिवार्य एक प्रकाश अवशोषक molecule बनाता है I
Vitamin A की कमी से Xerophthalmia नामक बीमारी हो जाती है जिसमें आँखों में सूखापन हो जाता है और यदि
इसका इलाज नहीं किया जाए तो रतौंधी (night blindness) बीमारी हो सकती है I
Visual cycle of rod cells -
आँख की retina में दो प्रकार क
े photoreceptor cells होती हैं - rod cells और cone cells जो क्रमशः धीमी और
तेज light में दृष्टि क
े लिए ज़िम्मेदार होती हैं I Rod cells में प्रकाश अवशोषक conjugated protein होती है
जिसे rhodopsin कहते हैं और यह protein opsin और vitamin A क
े aldehyde (11-cis-retinal) से मिलकर
बनी होती है I Visual cycle शुरू होती है light की प्रतिक्रिया स्वरुप जिससे rhodopsin का 11-cis-retinal
isomerise होता है all-trans-retinal में और यह all-trans-retinal rhodopsin से अलग हो जाता है तथा retina
में nerve impulse दृष्टि क
े लिए उत्प्रेरित हो जाती है, brain क
े प्रकाश का अनुभव करते ही I Rhodopsin क
े
पुनर्निर्माण हेतु all-trans-retinal NADH की उपस्थिति में एक enzyme की मदद से all trans- vitamin A में
परिवर्तित हो जाता है I यह all-trans-vitamin A isomerise होकर 11-cis-vitamin A में बदल जाता है जो
NAD+ की उपस्थिति में आगे oxidise होकर 11-cis-retinal में बदल जाता है I अंत में 11-cis-retinal, opsin से
मिलकर visual cycle को पूरा करने हेतु rhodopsin को पुनः बना देता है I इस प्रकार यह पुनर्जनित rhodopsin
अगली visual cycle में भाग लेता है I
2

3. Q.3. Draw the structure of vitamin B6 and vitamin C. What are the symptoms of the
disease caused by their deficiency? [विटामिन B6 और विटामिन C की संरचना बनाएं I इनकी कमी से
होने वाले लक्षणों को लिखें I]
Ans.
Vitamin C deficiency causes scurvy which is characterized by anemia, loss of weight, feeling of
tiredness, swollen and bleeding gums and hemorrhage in the mucous membranes.
[Vitamin C की कमी से scurvy रोग हो जाता है जिसमें anemia, शरीर क
े वजन में कमी, थकान, मसूड़ों से खून
बहना एवं सूजन और mucous membranes से रक्तस्राव आदि होता है I]
Vitamin B6 deficiency results in dermatitis in rats which is characterized by swelling and edema
of ears, paws and nose. In humans it produces convulsions, chronic anemia and peripheral
neuropathy.
[Vitamin B6 की कमी से चूहों में dermatitis होती है जिसमें कान, नाक और पंजों में सूजन और edema हो जाता
है I मनुष्यों में इसकी कमी से convulsions, chronic anemia और peripheral न्यूरोपैथी हो सकते हैं I]
Q.4. Write the physiological roles of riboflavin (B2). [Riboflavin (विटामिन B2) की शारीरिक
भूमिका लिखें I]
Ans. The coenzymic forms of riboflavin FMN and FAD participate in oxidation reduction
reactions e.g. succinate dehydrogenase catalysing the conversion of succinate to fumarate in
presence of FAD.
FMN is the prosthetic group of enzyme NADH dehydrogenase and serves as hydrogen carrier
for oxidation reduction reaction.
The deficiency of riboflavin results in abnormal vision and corneal inflammation in humans and
inadequate growth, loss of hair and cataract in animals.
[Riboflavin क
े coenzyme रूप FMN और FAD oxidation reduction reactions में भाग लेते हैं, जैसे -
succinate dehydrogenase enzyme FAD की उपस्थिति में succinate को fumarate में परिवर्तित करता है I
FMN NADH dehydrogenase enxyme का prosthetic group है और यह oxidation reduction reaction
में hydrogen carrier का काम करता है I
Riboflavin की हमारे शरीर में कमी से abnormal vision और corneal inflammation हो जाता है तथा
animals में अपर्याप्त वृद्धि, बालों का झड़ना और cataract होता है I]
Q. 5. Name the provitamins of vitamin D and the two main compounds having vitamin D
activity and how these are formed. Name the biologically active form of vitamin D3. Write
the functions of vitamin D and name the disease caused by its deficiency.[विटामिन D क
े
provitamins क
े नाम और विटामिन D activity रखने वाले दो मुख्य compounds क
े नाम लिखें I विटामिन
D3 क
े biologically active form का नाम लिखें I विटामिन D क
े कार्य और इसकी कमी से होने वाली बीमारी
लिखें I]
3

4. Ans. The provitamins of vitamin D are ergosterol (a plant sterol) and 7-dehydrocholesterol (an
animal sterol). The two main compounds having vitamin D activity are Calciferol (D2;formed by
UV irradiation of Ergosterol in yeast and moulds) and Cholecalciferol ( D3; formed by UV
irradiation of 7-dehydrocholesterol present in skin). The biologically active form of vitamin D 3 is
calcitriol (1,25-dihydroxy Cholecalciferol).
Vitamin D is involved in utilization of calcium and phosphorus for the normal formation of bones
and teeth. It stimulates the absorption of calcium and phosphorus from the intestine. Its
deficiency results in disease called rickets. In addition, its deficiency may cause brittle bones
and muscle weakness.
[Vitamin D क
े provitamin हैं - ergosterol (एक plant sterol) और 7-dehydrocholesterol (एक animal
sterol) और vitamin activity वाले दो मुख्य main compounds हैं - Calciferol (D2; जो ergosterol क
े UV
irradiation से yeast और moulds में बनता है) और Cholecalciferol (D3; जो skin में उपस्थित
7-dehydrocholesterol क
े UV irradiation से बनता है) I Vitamin D3 का biologically active form
calcitriol (1,25-dihydroxy Cholecalciferol) है I
Vitamin D bones और teeth क
े सामान्य रूप से बनने क
े आवश्यक calcium और phosphorous क
े ठीक से
उपयोग में शामिल होता है I यह calcium और phosphorus क
े intestine द्वारा absorption को stimulate
करता है I इसकी कमी से rickets नामक बीमारी होती है I इसक
े अलावा भंगुर हड्डियों और मांसपेशियों की
कमजोरी जैसी स्वास्थ्य समस्यायें भी हो सकती हैं I]
Q. 6. Mention the physiological role of vitamin B1, niacin and folic acid.[विटामिन B1,
niacin और folic acid क
े शारीरिक कार्यों क
े बारे में लिखें I]
Ans.
Vitamin B1 -
● The active coenzyme form of vitamin B1 (Thiamine) is thiamine pyrophosphate or
cocarboxylase which participates in the decarboxylation of α-keto acids such as pyruvic
acid.
[Vitamin B1 (Thiamine) का coenzyme रूप thiamine pyrophosphate या cocarboxylase
कहलाता है जो α-keto acids, जैसे - pyruvic acid, क
े decarboxylation में भाग लेता है I]
● Vitamin B1 deficiency may cause beriberi disease in humans and polyneuritis in animals.
This leads to nerve and muscle pain, numbness of the extremities and circulatory
disorders.
[Vitamin B1 की कमी से मनुष्यों में बेरीबेरी बीमारी होती है और जानवरों में polyneuritis बीमारी होती
है I इसमें nerve और muscle में pain, हाथ - पैर में सुन्नपन और संचार संबंधी विकार होते हैं I]
● Its deficiency also causes loss of appetite.
[इसकी कमी से भूख में कमी भी हो जाती है I]
Niacin -
● Nicotinic acid and nicotinamide are collectively called niacin. The amide form of niacin
forms part of two important coenzymes, nicotinamide adenine dinucleotide (NAD) and
nicotinamide adenine dinucleotide phosphate (NADP), of several oxidoreductases.
[Nicotinic acid और nicotinamide सम्मिलित रूप से niacin कहलाते हैं I Niacin का amide रूप कई
Oxidoreductases क
े दो महत्वपूर्ण coenzymes, nicotinamide adenine dinucleotide (NAD)
और nicotinamide adenine dinucleotide phosphate (NADP), का हिस्सा होता है I]
● Deficiency of niacin causes pellagra disease in humans which results in loss of appetite,
sore tongue, diarrhea and mental disturbances.
4

5. [Niacin की कमी से मनुष्यों में pellagra बीमारी हो जाती है जिसमें भूख में कमी, जीभ क
े घाव, दस्त
और मानसिक अशांति होती हैं I]
Folic acid -
● The coenzyme form of folic acid is 5,6,7,8-tetrahydrofolic acid which is involved in
biosynthesis of purines, pyrimidines, serine and glycine.
[Folic acid का coenzyme form 5,6,7,8-tetrahydrofolic acid होता है जो purines, pyrimidines,
serine और glycine की biosynthesis में शामिल होता है I]
● Its deficiency leads to anemia and failure of growth.
[Folic acid की कमी से anemia और वृद्धि में विफलता होती है I]
● Its deficiency also leads to impairment of cell division, accumulation of toxic metabolites,
and impairment of methylation reactions required for regulation of gene expression.
[इसकी कमी से cell division में क्षति, toxic metabolites का जमाव तथा gene expression क
े लिए
आवश्यक methylation reaction में कमी आदि भी होता है I]
Q. 7. Identify macrominerals and trace elements[इन macrominerals और trace elements को
पहचानें]- calcium, sodium, potassium, magnesium, iron, zinc, copper, iodine, phosphorus,
fluoride.
Ans.
Calcium - macromineral
Sodium - macromineral
Potassium - macromineral
Magnesium - macromineral
Iron - trace element
Zinc - trace element
Copper - trace element
Iodine - trace element
Phosphorus - macromineral
Fluoride - trace element
Q. 8. Describe briefly the physiological role played by iron and calcium.[Iron और क
ै ल्शियम
क
े शारीरिक कार्यों का वर्णन करें I]
Ans.
Iron -
● Iron is found in bulk amounts in the haem portion of hemoglobin and haem plays a
crucial role in the transport of oxygen to the entire body.
[हीमोग्लोबिन क
े heme portion में iron बड़ी मात्रा में पाया जाता है और heme पूरे शरीर में ऑक्सीजन
क
े ट्रांसपोर्ट में महत्वपूर्ण भूमिका निभाता है I]
● Iron is also a part of haem portion of cytochromes, hence involved in the electron
transport system.
[Iron cytochromes क
े heme portion का भी हिस्सा होता है जो electron transport system में
शामिल होता है I]
● Deficiency of iron causes anemia and also results in increased heart and respiratory
rates.
[Iron की कमी होने पर anemia होता है तथा heart rate एवं respiratory rate भी बढ़ जाता है I]
5

6. Calcium -
● Calcium is one of the most essential macrominerals required for several life processes.
[Calcium अतिआवश्यक macrominerals में से एक है जो कई जैव प्रक्रियाओं क
े लिए आवश्यक होता है
I]
● It is required for growth and maintenance of the skeletal system, tooth formation, muscle
contraction, mental activity, nerve impulse transmission and blood clotting.
[यह skeleton system की वृद्धि एवं रखरखाव, दांतों क
े बनने, muscle contraction, mental
activity, nerve impulse transmission और blood clotting क
े लिए आवश्यक होता है I]
● Chronic calcium deficiency can result in numbness in fingers and toes, muscle cramps,
brittle nails, dry skin, osteoporosis and tooth decay.
[क
ै ल्शियम की दीर्घकालिक कमी उँगलियों एवं अंगूठे में सुन्नपन, मांसपेशियों में ऐंठन, भंगुर नाख़ून,
सूखी त्वचा, osteoporosis और दांतों की संड़न का कारण हो सकती है I]
Q. 9. Describe briefly the physiological role played by sodium, potassium and
chloride.[सोडियम, पोटेशियम और chloride क
े शारीरिक कार्यों का संक्षिप्त विवरण दें I]
Ans.
Sodium, potassium and chloride are located in the extracellular and intracellular fluid. Within the
extracellular fluid, the major cation is sodium and the major anion is chloride. The major cation
in the intracellular fluid is potassium. These body electrolytes play an important role in
maintaining homeostasis.
[Sodium, potassium और chloride extracellular और intracellular fluid में होते हैं I Extracellular fluid में
मुख्य cation sodium और मुख्य anion chloride होता है जबकि intracellular fluid में मुख्य cation
potassium होता है I ये शरीर क
े electrolytes की समस्थिति (homeostasis) बनाए रखने में महत्वपूर्ण भूमिका
निभाते हैं I]
● Sodium is the principal cation of extracellular fluid (ECF) and primary regulator of blood
volume. It also helps maintain acid-base balance and is essential for nerve impulse
transmission and muscle contraction.
[Sodium extracellular fluid (ECF) का मुख्य cation होता है और blood क
े volume का प्राथमिक
नियंत्रक होता है I यह शरीर क
े acid-base balance को भी बनाए रखने में मदद करता है और nerve
impulse transmission एवं muscle contraction क
े लिए अनिवार्य होता है I]
● Low blood sodium (hyponatremia) may cause cerebral oedema and increased
intracranial pressure with symptoms like agitation, disorientation, headache, nausea and
vomiting.
[Low blood sodium (hyponatremia) क
े कारण cerebral oedema और intracranial pressure
बढ़ सकता है जिससे agitation, disorientation, headache, nausea और vomiting जैसे
symptoms हो सकते हैं I]
● High blood sodium (hypernatremia) causes excessive thirst, muscle twitching or spasms,
and seizures and coma in severe elevation of sodium.
[High blood sodium (hypernatremia) क
े कारण अत्यधिक प्यास लगती है और मांसपेशियों में
फड़कन (muscle twitching) या ऐंठन (spasms), तथा sodium स्तर क
े अत्यधिक बढ़ने पर दिमागी
दौरा (seizures) और निश्चेतावस्था (coma) की स्थिति हो सकती है I]
6

7. ● Potassium is essential for maintenance of membrane potential and excitability for nerve
impulse transmission.
[Potassium nerve impulse transmission क
े लिए आवश्यक membrane potential और
excitability क
े रखरखाव क
े लिए अनिवार्य होता है I]
● Low blood potassium (hypokalemia) may cause temporary memory loss, irregular heart
beat, increased blood pressure and muscle weakness & cramps.
[Low blood potassium (hypokalemia) क
े कारण temporary memory loss, irregular heart
beat, increased blood pressure और muscle में कमज़ोरी एवं मरोड़ (cramps) हो सकते हैं I]
● High plasma potassium (hyperkalemia) may cause abnormal heart and skeletal muscle
function.
[High plasma potassium (hyperkalemia) heart और skeletal muscles क
े कार्यों को असामान्य
कर सकता है I]
● Chloride regulates osmotic pressure and assists in regulating acid-base balance.
[Chloride osmotic pressure को नियंत्रित करता है और acid-base balance क
े नियंत्रण में सहायता
करता है I]
● Na+, K+ and Cl- ions are necessary for the production of digestive secretions and for
normal eye functions.
[Na+, K+ और Cl- ions digestive secretions क
े उत्पादन तथा आँखों क
े सामान्य कार्यों क
े लिए भी
आवश्यक होते हैं I]
Q. 10. Fill in the blanks-
(i) Vitamin B and C are _______ soluble vitamins.
(ii) Vitamins A, D, E and K are ________ soluble vitamins.
(iii) ______ soluble vitamins must be present in our daily diet because these vitamins are
regularly eliminated from the body in the urine.
(iv) All water soluble vitamins can be synthesized by plants except vitamin _____.
(v) The disease Beriberi is caused by the deficiency of vitamin _______.
(vi) Thiamine pyrophosphate is the active coenzyme form of vitamin _____.
(vii) FMN and FAD are the coenzymic forms of vitamin ________.
(viii) ______ and ______ are the coenzymes required for oxidation - reduction enzymes.
(ix) Pellagra disease is caused by the deficiency of vitamin _______.
(x) NAD and NADP coenzymes contain the amide form of the vitamin ________.
(xi) Pantothenic acid is vitamin _________.
(xii) The coenzyme form of Pantothenic acid is _________.
(xiii) The three compounds having vitamin B6 activity are _______, ________ and ______.
(xiv) The coenzymic forms of vitamin B6 are _______ and _______.
(xv) Dermatitis in rats and convulsions, chronic anemia and peripheral neuropathy in humans is
caused by the deficiency of vitamin ______.
(xvi) The excessive eating of raw egg white results in deficiency of _______.
(xvii) The symptoms of macrocytic anaemia can be reduced by treatment with _______ acid.
(xviii) The coenzymic form of folic acid is _________.
(xix) Pernicious anemia is caused by the deficiency of vitamin ______.
(xx) The dietary source of vitamin B12 is _____.
(xxi) The metal found in the structure of cyanocobalamin is ______.
7

8. (xxii) The deficiency of vitamin C results in a disease called ______.
(xxiii) The vitamin with no known coenzymic activity is vitamin ______.
(xxiv) The diseases xerophthalmia and night blindness are caused by the deficiency of vitamin
_____.
(xxv) Vitamin D2 is found in _____ and vitamin D3 in _______.
(xxvi) The biologically active form of vitamin D is ______.
(xxvii) The chemical name of vitamin E is _______.
(xxviii) The vitamin important for blood clotting mechanism is vitamin ______.
(xxix) A lack of cobalt results in _______ anemia.
(xxx) Inadequate intake of _____ may result in goiter.
(xxxi) In absence of adequate iodine thyroid gland can not synthesize enough _______.
(xxxii) _______ is an important trace element for the prevention of dental caries but its excess
intake may result in ______`.
(xxxiii) The trace element ______ is an important constituent of enzyme cytochrome oxidase
and it circulates in plasma as ceruloplasmin.
(xxxiv) A deficiency of element _______ leads to subnormal growth and deficiency in gonadal
function.
(xxxv) Hemoglobin contains the element _____.
(xxxvi) The macromineral present in Acetyl CoA is _______.
(xxxvii) The chlorophyll molecule contains the metal element _______.
(xxxviii) The three body electrolytes which play an important role in maintaining homeostasis are
________, _______ and ______.
(xxxix) The macromineral present in nucleic acids is ________.
((xxxx) The element required for blood clotting is ______.
Ans. (i) water, (ii) fat, (iii) water, (iv) B12, (v) B1 or thiamine, (vi) B1 or thiamine, (vii) riboflavin,
(viii) FMN, FAD, (ix) niacin, (x) niacin, (xi) B5, (xii) coenzyme A, (xiii) pyridoxine, pyridoxal,
pyridoxamine, (xiv) pyridoxal phosphate, pyridoxamine phosphate, (xv) B6 (xvi) biotin, (xvii)
folic, (xviii) 5,6,7,8-tetrahydrofolic acid, (xix) B12 (xx) liver, (xxi) cobalt, (xxii) scurvy, (xxiii) C,
(xxiv) A, (xxv) plants, animals, (xxvi) calcitriol, (xxvii) tocopherol, (xxviii) K, (xxix) pernicious,
(xxx) iodine, (xxxi) Thyroxine, (xxxii) fluorosis, (xxxiii) copper, (xxxiv) zinc, (xxxv) iron, (xxxvi)
sulphur, (xxxvii) magnesium, (xxxviii) sodium, potassium, chloride, (xxxix) phosphorus, (xxxx)
calcium
REFERENCES:
1. IGNOU, CHE - 9 Biochemistry, Block 2
2. Lehninger Principles of biochemistry, seventh edition ; David L. Nelson & Michael M. Cox.
Disclaimer : The pictures given in the text have been downloaded from Google images and I am
thankful to the persons who have uploaded these pictures.
Dr. P. K. Nigam (Retired Biochemist)
8