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Questions and Answers
Which vitamin is primarily involved in calcium and phosphate metabolism?
Which vitamin is primarily involved in calcium and phosphate metabolism?
What deficiency is associated with inadequate vitamin K intake in newborns?
What deficiency is associated with inadequate vitamin K intake in newborns?
What is the primary function of vitamin E in the human body?
What is the primary function of vitamin E in the human body?
Which of the following vitamins can result in toxicity if taken in excess?
Which of the following vitamins can result in toxicity if taken in excess?
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What compounds are known to be precursors of vitamin A?
What compounds are known to be precursors of vitamin A?
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Which vitamin is primarily responsible for vision and cell differentiation?
Which vitamin is primarily responsible for vision and cell differentiation?
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What is the condition caused by a deficiency of vitamin D in children?
What is the condition caused by a deficiency of vitamin D in children?
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What forms the visual pigment rhodopsin in the retina?
What forms the visual pigment rhodopsin in the retina?
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What is formed when pantothenate combines with cysteine?
What is formed when pantothenate combines with cysteine?
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Which of the following processes involves CoA?
Which of the following processes involves CoA?
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What is a primary source of vitamin B12?
What is a primary source of vitamin B12?
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What condition results from vitamin B12 deficiency affecting folic acid metabolism?
What condition results from vitamin B12 deficiency affecting folic acid metabolism?
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Which enzyme is NOT dependent on vitamin B12?
Which enzyme is NOT dependent on vitamin B12?
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What is the active form of folic acid?
What is the active form of folic acid?
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How can homocysteine be remethylated?
How can homocysteine be remethylated?
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What characterizes the corrinoids that are active as vitamin B12?
What characterizes the corrinoids that are active as vitamin B12?
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What condition is associated with a deficiency of thiamin?
What condition is associated with a deficiency of thiamin?
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Which vitamin is a coenzyme for the pyruvate dehydrogenase complex?
Which vitamin is a coenzyme for the pyruvate dehydrogenase complex?
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Which disease is characterized by confusion and changes to the eyes associated with vitamin B1 deficiency?
Which disease is characterized by confusion and changes to the eyes associated with vitamin B1 deficiency?
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What type of beriberi is characterized by edema and cardiac failure?
What type of beriberi is characterized by edema and cardiac failure?
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Which syndrome is specifically linked to chronic alcohol misuse and thiamin deficiency?
Which syndrome is specifically linked to chronic alcohol misuse and thiamin deficiency?
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What is a common general symptom of thiamin deficiency?
What is a common general symptom of thiamin deficiency?
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Which vitamin deficiency leads to conditions such as glossitis and cheilosis?
Which vitamin deficiency leads to conditions such as glossitis and cheilosis?
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What deficiency can lead to rickets in children?
What deficiency can lead to rickets in children?
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What is a characteristic condition of niacin deficiency?
What is a characteristic condition of niacin deficiency?
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Which form of vitamin D is generated from cholesterol in the skin upon sunlight exposure?
Which form of vitamin D is generated from cholesterol in the skin upon sunlight exposure?
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What is the principal role of calcitriol in the body?
What is the principal role of calcitriol in the body?
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Which of the following conditions is NOT typically treated with vitamin D?
Which of the following conditions is NOT typically treated with vitamin D?
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What triggers the reduction of calcitriol synthesis in the body?
What triggers the reduction of calcitriol synthesis in the body?
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What is the major storage form of vitamin D in the plasma?
What is the major storage form of vitamin D in the plasma?
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Which is a consequence of excessive vitamin D intake in infants?
Which is a consequence of excessive vitamin D intake in infants?
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In which organ is 25-hydroxy cholecalciferol primarily hydroxylated to form calcitriol?
In which organ is 25-hydroxy cholecalciferol primarily hydroxylated to form calcitriol?
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What is the primary consequence of thiamin diphosphate deficiency in relation to pyruvate?
What is the primary consequence of thiamin diphosphate deficiency in relation to pyruvate?
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Which of the following is a dietary source of riboflavin?
Which of the following is a dietary source of riboflavin?
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What role does riboflavin play in energy production?
What role does riboflavin play in energy production?
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Which deficiency is characterized by photosensitive dermatitis, dementia, and diarrhea?
Which deficiency is characterized by photosensitive dermatitis, dementia, and diarrhea?
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How is riboflavin nutritional status generally assessed?
How is riboflavin nutritional status generally assessed?
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Which statement about niacin is correct?
Which statement about niacin is correct?
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What is a potential fatal outcome of untreated pellagra?
What is a potential fatal outcome of untreated pellagra?
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What additional factors can contribute to the development of pellagra besides niacin deficiency?
What additional factors can contribute to the development of pellagra besides niacin deficiency?
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What is the primary effect of vitamin B12 deficiency on folate metabolism?
What is the primary effect of vitamin B12 deficiency on folate metabolism?
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Which of the following conditions is primarily associated with deficiency of folic acid or vitamin B12?
Which of the following conditions is primarily associated with deficiency of folic acid or vitamin B12?
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What role does ascorbic acid play in enzyme function?
What role does ascorbic acid play in enzyme function?
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What is the primary dietary source of vitamin C for humans and other primates?
What is the primary dietary source of vitamin C for humans and other primates?
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What happens to vitamin C metabolism at intakes above approximately 100 mg/day?
What happens to vitamin C metabolism at intakes above approximately 100 mg/day?
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Which activity does vitamin C NOT directly influence?
Which activity does vitamin C NOT directly influence?
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Which group of animals typically does not synthesize vitamin C?
Which group of animals typically does not synthesize vitamin C?
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What indicates a vitamin C deficiency in humans?
What indicates a vitamin C deficiency in humans?
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Study Notes
Vitamins
- Vitamins are organic nutrients needed in small amounts for various biochemical functions.
- They are generally not synthesized by the body and must be obtained through diet.
- Vitamins are classified as either fat-soluble or water-soluble.
Fat-Soluble Vitamins
- Fat-soluble vitamins are absorbed efficiently only when fat absorption is normal.
- They are transported in the blood through lipoproteins or specific binding proteins.
- Fat-soluble vitamins have diverse functions.
- Vitamin A: vision and cell differentiation
- Vitamin D: calcium and phosphate metabolism; cell differentiation
- Vitamin E: antioxidant
- Vitamin K: blood clotting
Water-Soluble Vitamins
- Water-soluble vitamins include the B vitamins and vitamin C.
- They function mainly as enzyme cofactors.
- Deficiency of a single B vitamin is uncommon, as poor diets typically involve multiple deficiencies.
- Vitamin B1 (thiamine): central role in energy-yielding metabolism, especially carbohydrate metabolism
- Vitamin B2 (riboflavin): precursor or building blocks for coenzymes (important for energy production)
- Vitamin B3 (niacin): involved in oxidation/reduction reactions, source of ADP-ribose
- Vitamin B5 (pantothenic acid): central role in acyl group metabolism
- Vitamin B6 (pyridoxine): involved in amino acid metabolism
- Vitamin B7 (biotin): transfers carbon dioxide; involved in cell cycle regulation
- Vitamin B9 (folic acid): active form is tetrahydrofolate, one-carbon fragments, N-5 and N-10 bridge -Vitamin B12 (cobalamin): cobalamins (cobalt-containing compounds) which are growth factors, essential for microorganisms(important for many enzymatic functions).
- Vitamin C: function in glucose metabolism/acting as an antioxidant / essential for the copper-containing hydroxylases and the α-ketoglutarate-linked iron-containing hydroxylases
Vitamin A
- Retinoids include retinol, retinaldehyde, and retinoic acid, found in animal products.
- Carotenoids are plant-based precursors for vitamin A.
- Beta-carotene and other provitamin A carotenoids are cleaved in the intestinal mucosa to yield retinaldehyde, which is then reduced to retinol.
Vitamin D
- Vitamin D's primary function is regulating calcium absorption and homeostasis.
- Vitamin D acts by way of nuclear receptors which regulate gene expression.
- Vitamin D regulates cell proliferation and differentiation.
- Sufficient intake reduces risk of insulin resistance, obesity, and metabolic syndrome.
- Dietary sources are ergocalciferol (vitamin D2) from plants and cholecalciferol (vitamin D3) from animal tissues.
- Humans synthesize cholecalciferol through sunlight exposure.
- Vitamin D is not biologically active, but is converted to active form through sequential hydroxylation reactions in the liver and kidney.
Vitamin E
- Vitamin E acts as a lipid-soluble antioxidant in cell membranes and plasma lipoproteins.
- Vitamin E is important in maintaining cell membrane fluidity and plays a role in cell signaling.
- Common name for two types of compounds (tocopherols & tocotrienols).
- Common name is tocopherol.
Vitamin K
- Vitamin K is essential for carboxylation of glutamate residues in proteins, leading to γ-carboxyglutamate formation.
- This γ-carboxyglutamate is vital for binding of blood clotting factors (VII, IX, X, C, S) to membranes.
- Vitamin K deficiency (or warfarin use) leads to abnormal prothrombin (with little -carboxyglutamate) being released into the body.
Deficiency
- Vitamin A deficiency can cause night blindness and xerophthalmia (corneal keratinization).
- Vitamin A is crucial for immune cell development. Deficiency increases infectious disease susceptibility.
- Vitamin D deficiency leads to rickets in children and osteomalacia in adults.
- Vitamin E deficiency leads to abnormally fragile erythrocyte membranes, leading to hemolytic anemia.
- Vitamin K deficiency can lead to bleeding issues. (Blood clotting).
Toxicity
- Excessive intake of Vitamins A and D can lead to toxicity.
- Vitamin A toxicity results in skeletal abnormalities, liver enlargement, and skin abnormalities.
- Excessive Vitamin D can cause skeletal abnormalities, hypercalcemia, etc.
Additional Notes
- Many of the vitamins are important in the prevention or treatment or of many ailments.
- Vitamins act as either antioxidants, or components of enzymes or parts of cellular processes.
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Description
Test your knowledge on vitamins, including their classification into fat-soluble and water-soluble categories. Explore the essential roles that these nutrients play in biochemical functions and learn about the specific vitamins and their benefits. This quiz will enhance your understanding of vitamins and their dietary significance.
