Biochemistry of Vitamins
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Questions and Answers

Which vitamins are classified as fat-soluble vitamins?

  • Vitamin E, Vitamin B1, Vitamin D, Vitamin A
  • Vitamin A, Vitamin D, Vitamin E, Vitamin K (correct)
  • Vitamin C, Vitamin B12, Vitamin D, Vitamin E
  • Vitamin A, Vitamin B6, Vitamin C, Vitamin K
  • What is a primary source of active vitamin A?

  • Fruits and vegetables
  • Whole grains
  • Meat and fish liver oils (correct)
  • Dairy products only
  • Which function does vitamin A primarily serve in the body?

  • Protein synthesis
  • Energy production
  • Blood clotting
  • Vision (correct)
  • Which vitamin acts as a precursor to vitamin A from plant sources?

    <p>Beta-carotene (D)</p> Signup and view all the answers

    What is a primary effect of vitamin A deficiency?

    <p>Night blindness (C)</p> Signup and view all the answers

    Which vitamin is primarily responsible for the function of rod cells in dim light vision?

    <p>Vitamin A (B)</p> Signup and view all the answers

    What condition may result from a deficiency of vitamin A in the eye?

    <p>Night blindness (A)</p> Signup and view all the answers

    Which of the following vitamins does NOT yield energy but facilitates energy-yielding reactions?

    <p>Vitamin D (B)</p> Signup and view all the answers

    What is one of the roles of retinoic acid in the body?

    <p>Synthesis of glycoproteins (D)</p> Signup and view all the answers

    Which function is primarily associated with water-soluble vitamins?

    <p>Synthesis of collagen and neurotransmitters (A)</p> Signup and view all the answers

    Where can vitamin D3 be primarily obtained from?

    <p>Fish liver oils (D)</p> Signup and view all the answers

    Which of these vitamins is primarily obtained from animal sources?

    <p>Vitamin B12 (A)</p> Signup and view all the answers

    Which of the following is a symptom of vitamin A deficiency?

    <p>Skin roughness (D)</p> Signup and view all the answers

    How is vitamin D3 synthesized in the skin?

    <p>Conversion of cholesterol by UV rays (D)</p> Signup and view all the answers

    What effect does retinoic acid have on bone health?

    <p>It accelerates bone growth (D)</p> Signup and view all the answers

    Which of the following fruits is known for its high levels of carotenes?

    <p>Carrot (A)</p> Signup and view all the answers

    What condition is primarily caused by hypercalcemia due to abnormal calcification?

    <p>Kidney stones (A)</p> Signup and view all the answers

    Which type of tocopherol is known to be the most potent?

    <p>Alpha-Tocopherol (C)</p> Signup and view all the answers

    What is the primary dietary source of Vitamin K1?

    <p>Leafy green vegetables (C)</p> Signup and view all the answers

    Which of the following is NOT a function of Vitamin E?

    <p>Promotion of blood clotting (C)</p> Signup and view all the answers

    What factor can lead to a deficiency of Vitamin K?

    <p>Malabsorption syndromes (A)</p> Signup and view all the answers

    Which is true regarding the active forms of Vitamin A?

    <p>Retinol, retinal, and retinoic acid are active forms (A)</p> Signup and view all the answers

    What role do rods play in vision?

    <p>They are responsible for vision in dim light (D)</p> Signup and view all the answers

    What forms rhodopsin in the eyes?

    <p>11-trans retinal and opsin protein (C)</p> Signup and view all the answers

    Where is vitamin D primarily stored in the body?

    <p>Liver (C)</p> Signup and view all the answers

    What enzyme in the liver hydroxylates vitamin D3 to 25-(OH)-D3?

    <p>25-hydroxylase (D)</p> Signup and view all the answers

    Which hormone stimulates the synthesis of calcitriol in the kidney?

    <p>Parathyroid hormone (PTH) (A)</p> Signup and view all the answers

    What does a decrease in blood calcium levels stimulate?

    <p>Secretion of parathyroid hormone (PTH) (C)</p> Signup and view all the answers

    Which of the following is NOT a function of active vitamin D (Calcitriol)?

    <p>Increases absorption of vitamin C in the intestine (D)</p> Signup and view all the answers

    What condition is caused by vitamin D deficiency in young children?

    <p>Rickets (D)</p> Signup and view all the answers

    Which of the following is a common cause of vitamin D deficiency?

    <p>Minimal exposure to sunlight (C)</p> Signup and view all the answers

    What can lead to vitamin D toxicity?

    <p>Self-medication with vitamin D supplements (C)</p> Signup and view all the answers

    Flashcards

    Vitamins

    Organic compounds required in small amounts for normal health and growth. They are not synthesized by the human body and are essential for various metabolic processes.

    Fat-soluble vitamins

    Vitamins stored in the body's fat tissue, making them more likely to accumulate in excess.

    Water-soluble vitamins

    Vitamins that dissolve in water and are not stored in the body in significant amounts.

    Vitamin A

    A vitamin crucial for vision, cell growth, and immune function. Found in liver, dairy, and some fruits and vegetables.

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    Retinol

    The active form of vitamin A, involved in vision and cell growth.

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    Carotenoids

    Precursors of vitamin A found in plants, especially carrots, sweet potatoes, and spinach.

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    Vitamin A deficiency

    A deficiency of vitamin A, leading to night blindness and dry eyes, among other problems.

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    Xerophthalmia

    A severe form of vitamin A deficiency, characterized by dryness of the eyes, blindness, and potentially other health issues.

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    Rhodopsin

    A photosensitive pigment found in rod cells of the retina, responsible for vision in dim light. Composed of 11-cis retinal and opsin.

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    Iodopsin

    A photosensitive pigment found in cone cells of the retina, responsible for color vision in bright light.

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    Retinoic Acid

    A form of vitamin A that acts as a hormone. It plays roles in cell growth, immune function, and reproductive health.

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    7-dehydrocholesterol

    The precursor to vitamin D3, found in animal skin, converted to vitamin D3 by sunlight.

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    Ergosterol

    A plant-derived precursor to vitamin D2, present in foods like mushrooms.

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    Night Blindness

    The inability to see well in dim light, a symptom of vitamin A deficiency.

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    Xeroderma

    The term for a condition where the skin becomes rough and dry, a symptom of vitamin A deficiency.

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    Where is Vitamin D stored?

    The main storage site for Vitamin D in the body. This organ plays a crucial role in the activation process of Vitamin D.

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    What enzyme converts Vitamin D3 to 25-(OH)-D3?

    An enzyme responsible for converting Vitamin D3 into its active form, calcitriol. This process occurs in the liver.

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    What is the active form of Vitamin D called?

    The active form of Vitamin D, also known as 1,25-dihydroxycholecalciferol. It's vital for calcium absorption and bone health.

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    What hormone stimulates the production of calcitriol?

    A hormone that regulates blood calcium levels and stimulates the production of calcitriol. It's produced by the parathyroid glands.

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    What enzyme converts 25-(OH)-D3 to calcitriol?

    The enzyme in the kidneys that converts 25-(OH)-D3 into its active form, calcitriol. Its activity is regulated by PTH and blood calcium levels.

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    What are the main functions of calcitriol?

    Increased calcium absorption from the intestines, increased bone resorption, and increased calcium reabsorption in the kidneys. These processes are crucial for maintaining calcium homeostasis.

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    What condition occurs due to Vitamin D deficiency in children?

    A condition that develops due to Vitamin D deficiency, characterized by soft and weak bones. It's more prevalent in children.

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    What condition occurs due to Vitamin D deficiency in adults?

    A condition caused by Vitamin D deficiency in adults, characterized by weak and brittle bones. This can lead to bone pain and fractures.

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    What is vitamin E's role in the body?

    Vitamin E, also known as tocopherols, is a fat-soluble vitamin that acts as a potent antioxidant, protecting cells from damage caused by free radicals. It is crucial for healthy blood, muscles, and nerves.

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    What are the primary sources of vitamin E?

    Vitamin E is primarily obtained from various vegetable oils, such as wheat germ, cottonseed, olive, and coconut oils. Smaller amounts are present in liver, egg yolk, milk, and colostrum.

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    What is the primary function of vitamin K?

    Vitamin K is a fat-soluble vitamin that plays a vital role in blood clotting and bone health.

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    What is the main source of vitamin K1?

    Vitamin K1 is the major form of vitamin K found in plants, mainly in leafy green vegetables such as spinach, cauliflower, and cabbage.

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    What is the role of vitamin K2?

    Vitamin K2 is produced by bacteria in the gut. It's essential for bone health and plays a role in regulating blood calcium levels.

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    What are the consequences of vitamin K deficiency?

    Vitamin K deficiency can lead to prolonged clotting times and hemorrhagic manifestations, particularly in the skin and mucous membranes.

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    What are the causes of vitamin K deficiency?

    Deficiency of vitamin K can occur due to various factors, including deficient gut bacteria (as seen in prolonged antibiotic use and newborns), fat malabsorption syndromes, liver diseases, and long-term use of anticoagulant drugs like dicumarol.

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    Does vitamin K deficiency typically occur due to insufficient intake?

    Although vitamin K is widely distributed in food and synthesized by bacteria in the large intestine, deficiency is uncommon due to its widespread availability.

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    Study Notes

    Biochemistry of Vitamins

    • Vitamins are organic compounds
    • They are essential for human health and growth
    • Vitamins are required in small amounts
    • Deficiency of a vitamin can result in a specific nutrition deficiency disease
    • Vitamins are not synthesized in the human body, must be obtained from the diet
    • Vitamins do not participate in tissue structure like carbohydrates, fats, and proteins
    • Vitamins do not yield energy, but facilitate energy-yielding chemical reactions
    • Vitamins act as coenzymes
    • Vitamins are classified based on their solubility into two main groups: fat-soluble and water-soluble
    • Fat-soluble vitamins include vitamins A (ADEK)
    • Water-soluble vitamins include the B vitamins and vitamin C

    Fat-Soluble Vitamins

    • Vitamin A (retinol, retinal, retinoic acid)
      • Active forms of vitamin A are retinol, retinal, and retinoic acid.
      • Sources: Animal sources (meat, liver, milk, butter, egg yolk, fish liver oils) as retinol esters; plant sources (carrots, sweet potatoes) as carotenoids. α, β, γ-carotenes are important carotenoids, with β-carotene having the highest activity.
      • Functions:
        • Vision (rhodopsin in rods for dim light, iodopsin in cones for bright light)
        • Supports normal growth of bones and teeth
        • Role in reproduction in males and females
        • Immunostimulant
        • Anticancer agent, due to antioxidant properties
      • Deficiency: Night blindness, xerophthalmia (cornea drying), growth retardation, increased susceptibility to cancer and anemia, rough skin (xeroderma), and mucous membrane problems of urinary, genital, gastrointestinal, and respiratory tracts leading to infections.
    • Vitamin D (cholecalciferol/ergocalciferol)
      • Sources: Provitamin 7-dehydrocholesterol in animals and man; ergosterol in plants, converted to vitamin D3 (cholecalciferol) by UV exposure and vitamin D2 (ergocalciferol) by UV exposure
      • Active form: calcitriol (1,25-dihydroxycholecalciferol) is formed in the liver and kidney by enzymatic hydroxylation
      • Functions: Essential for calcium and phosphorus absorption in the intestines and bone mineralization.
      • Deficiency: Rickets in children and osteomalacia in adults.
      • Regulation: Controlled by parathyroid hormone (PTH) and blood calcium and phosphate levels.
    • Vitamin E (tocopherols)
      • Sources: Vegetable oils (wheat germ, cottonseed, olive, coconut), liver, egg yolk, milk, colostrum,
      • Functions: Antioxidant, prevents hemolytic anemia, important for pregnancy in animals
    • Vitamin K (phylloquinone/menaquinone)
      • Sources: Plants (spinach, cauliflower, cabbage) as phylloquinone; bacteria in the intestines as menaquinone
      • Functions: Antihemorrhagic (essential for blood clotting), activates osteocalcin in bone.

    Water-Soluble Vitamins

    • Information on Water-Soluble Vitamins not included in the provided text.

    Vitamin Toxicity

    • Vitamin D toxicity (Hypervitaminosis): Usually occurs due to self-medication. Results in hypercalcemia, leading to abnormal calcification in soft tissues (like kidney) and blood vessels, and potentially hypertension

    Additional Note

    • The provided text included multiple questions. Those questions are not included in the summary as the summary focused on the main topics.

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    Description

    Explore the essential role of vitamins in human health and growth through this quiz. Learn about their classifications, sources, functions, and the consequences of deficiencies. Discover the distinction between fat-soluble and water-soluble vitamins.

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