Vitamins and Their Functions
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Questions and Answers

What is the precursor of vitamin D3 derived from?

  • Calcitriol
  • Vitamin K
  • 7-dehydrocholesterol (correct)
  • Cholesterol

    • What is the primary function of calcitriol in the body?

  • To act as an antioxidant
  • To activate blood clotting proteins
  • To facilitate iron absorption
  • To regulate calcium and phosphorous homeostasis (correct)

    • What is the result of vitamin D deficiency in children?

  • Anemia
  • Scurvy
  • Osteomalacia
  • Rickets (correct)

    • What is the primary function of vitamin E in the body?

    <p>To act as an antioxidant</p> Signup and view all the answers

    What is the result of vitamin K deficiency?

    <p>Defective blood clotting and hemorrhage</p> Signup and view all the answers

    What is the function of vitamin C in collagen synthesis?

    <p>To hydroxylate proline and lysine residues</p> Signup and view all the answers

    What is the result of rickets in children?

    <p>All of the above</p> Signup and view all the answers

    What is the function of vitamin C in tyrosine metabolism?

    <p>To synthesize epinephrine from tyrosine</p> Signup and view all the answers

    What is the primary function of vitamins in the body?

    <p>To act as cofactors for enzymatic reactions</p> Signup and view all the answers

    Which of the following vitamins is NOT a fat-soluble vitamin?

    <p>Vitamin C</p> Signup and view all the answers

    What is the role of retinol in the body?

    <p>It is a precursor to vitamin A</p> Signup and view all the answers

    What is the result of hyperkeratinization of the cornea in vitamin A deficiency?

    <p>Corneal opacities</p> Signup and view all the answers

    What is the biologically active form of vitamin D?

    <p>Calcitriol</p> Signup and view all the answers

    What is the role of vitamins in the diet?

    <p>To supplement essential nutrients</p> Signup and view all the answers

    What is the result of vitamin A deficiency on the bones and teeth?

    <p>Abnormal formation of bones and teeth</p> Signup and view all the answers

    What is the function of rhodopsin pigments in the eye?

    <p>To enable vision in dim light</p> Signup and view all the answers

    What is the primary function of thiamine pyrophosphate in carbohydrate metabolism?

    <p>Acts as a coenzyme in oxidative decarboxylation reactions</p> Signup and view all the answers

    What is the primary consequence of vitamin C deficiency?

    <p>Scurvy</p> Signup and view all the answers

    Which vitamin is required for the synthesis of coenzyme A?

    <p>Vitamin B5</p> Signup and view all the answers

    What is the primary role of flavin mononucleotide (FMN) and flavin adenine dinonucleotide (FAD) in vitamin B2 metabolism?

    <p>Act as hydrogen carriers</p> Signup and view all the answers

    What is the primary consequence of niacin deficiency?

    <p>Pellagra</p> Signup and view all the answers

    What is the active form of folic acid?

    <p>Tetrahydrofolic acid</p> Signup and view all the answers

    What is the primary function of pyridoxal phosphate in amino acid metabolism?

    <p>Acts as a coenzyme in transamination reactions</p> Signup and view all the answers

    What is the primary consequence of vitamin B1 deficiency?

    <p>Beri Beri</p> Signup and view all the answers

    Study Notes

    Vitamins

    • Vitamins are small organic molecules required in small quantities for various biochemical functions.
    • They are essential cofactors for enzymatic reactions and cannot be synthesized by mammalian cells.
    • Deficiency in vitamins produces characteristic diseases.

    Classification of Vitamins

    • Vitamins are divided into two types based on solubility:
      • Fat-soluble vitamins: A, D, E, and K.
      • Water-soluble vitamins: C and B complex.

    Vitamin A

    • Exists in three biologically active forms: retinol, retinal, and retinoic acid.
    • Sources: animal sources like liver, egg yolk, and milk; carotenoids are provitamin A.
    • Functions:
      • Maintenance of epithelium and mucous membranes.
      • Antioxidant activity.
      • Formation of healthy connective tissues, bones, and teeth.
      • Gene control and regulation of cell growth and differentiation.
      • Vision: forms rhodopsin pigments responsible for vision in dim light.
    • Deficiency: leads to night blindness, hyperkeratinization, and increased risk of cancer.

    Vitamin D

    • Biologically active form: calcitriol.
    • Sources: liver, egg yolk, and cod liver oil; 7-dehydrocholesterol is converted into vitamin D3 by UV irradiation.
    • Functions:
      • Regulates calcium and phosphorus homeostasis.
      • Increases calcium absorption and reabsorption in the intestine and kidney.
      • Deposition of calcium and phosphate in bone (mineralization).
    • Deficiency: leads to rickets in children and osteomalacia in adults.

    Vitamin E

    • Function: natural antioxidant preventing peroxidation of polyunsaturated membrane fatty acids.

    Vitamin K

    • Function: activates blood clotting proteins, factors II, VII, IX, and X.
    • Deficiency: leads to defective blood clotting and hemorrhage.

    Vitamin C

    • Functions:
      • Potent antioxidant.
      • Absorption of iron by maintaining it in the ferrous state.
      • Cofactor for hydroxylation of proline and lysine residues in collagen.
      • Tyrosine metabolism and synthesis of epinephrine from tyrosine.
      • Synthesis of bile acids and steroidogenesis.
    • Deficiency: leads to scurvy, characterized by capillary fragility, soft swollen gums, and decreased wound healing.

    Vitamin B Complex

    Vitamin B1 (Thiamine)

    • Function: thiamine pyrophosphate (TPP) acts as a coenzyme in oxidative decarboxylation reactions in carbohydrate metabolism.
    • Deficiency: leads to Beri Beri, characterized by GIT, neurological, and cardiovascular manifestations.

    Vitamin B2 (Riboflavin)

    • Function: flavin mononucleotide (FMN) and flavin adenine dinonucleotide (FAD) act as hydrogen carriers.

    Vitamin B3 (Niacin or Nicotinic acid)

    • Function: nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP) act as hydrogen carriers.
    • Deficiency: leads to Pellagra, characterized by diarrhea, dermatitis, and dementia.

    Vitamin B5 (Pantothenic Acid)

    • Function: required for synthesis of coenzyme A, necessary for metabolism of carbohydrates, fats, and proteins.

    Vitamin B6

    • Function: pyridoxal phosphate (PLP) is a coenzyme for transamination reactions, required for synthesis and catabolism of amino acids, decarboxylation of amino acids, and in heme synthesis.

    Folic Acid

    • Function: tetrahydrofolic acid (FH4) acts as a coenzyme in protein metabolism and promotes red blood cell formation.
    • Deficiency: leads to Megaloblastic anemia.

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    Description

    Learn about the importance of vitamins in the body, their role in biochemical functions, and the effects of their deficiency. Discover how vitamins act as cofactors for enzymatic reactions and why they are essential in our diet.

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