Nucleic Acids: Structure and Composition
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Questions and Answers

Which monomers are used to build the nucleic acids DNA and RNA?

  • Monosaccharides
  • Amino acids
  • Nucleotides (correct)
  • Fatty acids

    • Which nucleotide is present in RNA but not in DNA?

  • Cytosine
  • Thymine
  • Uracil (correct)
  • Adenine

    • What are the components of a nucleotide?

  • A sugar, a phosphate group, and an amino acid
  • A base, an amino acid, and a phosphate group
  • A base, a sugar, and a phosphate group (correct)
  • A lipid, a sugar, and a phosphate group

    • What forms the backbone of a nucleic acid chain?

    <p>Sugars and phosphates</p> Signup and view all the answers

    What type of charge does each phosphate group carry at normal pH?

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

    Which sugar is found in RNA nucleotides?

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

    Which of the following nucleotides serve as coenzymes?

    <p>ATP, GTP, UTP, and CTP</p> Signup and view all the answers

    What is the primary role of nucleotides in respect to nucleic acids?

    <p>Component of nucleic acids</p> Signup and view all the answers

    What is the main role of ribonucleotides?

    <p>RNA synthesis</p> Signup and view all the answers

    Which molecule primarily serves as the source of free energy for all cellular activities?

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

    Which of the following is NOT a role of RNA?

    <p>Synthesizing new proteins directly from DNA</p> Signup and view all the answers

    What determines the sequence of proteins synthesized within the cell?

    <p>The sequence of bases (adenine, cytosine, guanine, and thymine) in DNA</p> Signup and view all the answers

    Which nucleotide pairs with guanine (G) in nucleic acids?

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

    What type of bond holds the nucleotide pairs together in nucleic acids?

    <p>Hydrogen bond</p> Signup and view all the answers

    Which component is not part of a nucleotide?

    <p>Hydrogen bond</p> Signup and view all the answers

    What does thymine (T) pair with in nucleic acids?

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

    Which of the following is an accurate pairing in nucleic acids?

    <p>Adenine (A) with Thymine (T)</p> Signup and view all the answers

    Which statement accurately describes a characteristic of vitamins?

    <p>They serve as coenzymes for many metabolic enzymes.</p> Signup and view all the answers

    Which of the following is NOT a cause of vitamin deficiency?

    <p>Excessive sunlight exposure</p> Signup and view all the answers

    What role do vitamins play in cellular function?

    <p>They act as catalysts in chemical reactions.</p> Signup and view all the answers

    Which vitamin characteristic ensures they must be supplied in the diet?

    <p>They are not synthesized by the human body with few exceptions.</p> Signup and view all the answers

    During which conditions might there be an increased requirement for vitamins?

    <p>Pregnancy and lactation</p> Signup and view all the answers

    What might a vitamin deficiency result in?

    <p>Various metabolic diseases</p> Signup and view all the answers

    What symptom can be produced by the destruction of intestinal microorganisms by antibiotic therapy?

    <p>Vitamin K deficiency</p> Signup and view all the answers

    Which of the following vitamins is NOT fat-soluble?

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

    Which of these vitamins is part of the vitamin B complex?

    <p>Vitamin B6</p> Signup and view all the answers

    How are vitamins classified based on their solubility?

    <p>Fat-soluble and water-soluble</p> Signup and view all the answers

    Which of these drugs can affect vitamin absorption or excretion by forming complexes with specific vitamins?

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

    Which function of vitamin E is specifically important for protecting RBCs?

    <p>Protection from hemolysis</p> Signup and view all the answers

    Which statement accurately describes vitamin E in terms of human fertility?

    <p>It is not essential for human fertility</p> Signup and view all the answers

    How does vitamin E contribute to reducing the risk of myocardial infarction?

    <p>By reducing oxidation of LDL</p> Signup and view all the answers

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

    <p>Increasing calcium absorption</p> Signup and view all the answers

    What effect does vitamin E have on the aging process?

    <p>It slows down the process of aging</p> Signup and view all the answers

    Which of the following conditions must be met for fat soluble vitamins to be absorbed?

    <p>Presence of bile salts</p> Signup and view all the answers

    In what form are fat soluble vitamins transported in the blood?

    <p>Bound to specific binding proteins</p> Signup and view all the answers

    What happens to fat soluble vitamins when their stores are depleted?

    <p>Their deficiency manifestations occur</p> Signup and view all the answers

    Why don't fat soluble vitamins get excreted in urine?

    <p>They are insoluble in water</p> Signup and view all the answers

    What is a potential risk associated with the over dosage of vitamins A and D?

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

    How is vitamin D (cholecalciferol) unique compared to other vitamins?

    <p>It is considered a hormone</p> Signup and view all the answers

    What is required for the synthesis of vitamin D from 7-dehydrocholesterol?

    <p>Exposure to sunlight</p> Signup and view all the answers

    Where is 7-dehydrocholesterol, the precursor of vitamin D, found in the body?

    <p>Subcutaneous fats</p> Signup and view all the answers

    Which of the following statements about vitamin D is true?

    <p>Its activity is unaffected by storage and cooking.</p> Signup and view all the answers

    Why is vitamin D not considered a typical vitamin?

    <p>It can be synthesized by the body.</p> Signup and view all the answers

    Where does the conversion of 25-hydroxy-vitamin D primarily occur?

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

    Which of the following is a rare group at risk of vitamin B12 deficiency?

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

    Vitamin B12 deficiency in elderly subjects is often due to malfunctioning of which cells?

    <p>Gastric parietal cells</p> Signup and view all the answers

    What critical factor is reduced due to malfunctioning gastric parietal cells leading to vitamin B12 deficiency?

    <p>Intrinsic factor</p> Signup and view all the answers

    Which condition can lead to vitamin B12 deficiency due to the body's inability to properly absorb nutrients?

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

    Apart from vegetarians, what is another group that might struggle with vitamin B12 deficiency?

    <p>Elderly with malfunctioning gastric parietal cells</p> Signup and view all the answers

    Which of the following statements about water-soluble vitamins is TRUE?

    <p>They must be provided continuously in the diet except for vitamin B12.</p> Signup and view all the answers

    What is the main reason that toxicities from water-soluble vitamins are rare?

    <p>They can be excreted in urine once concentrations exceed the renal threshold.</p> Signup and view all the answers

    What role do most water-soluble vitamins play in the body?

    <p>They serve as coenzymes or cofactors in enzymatic reactions.</p> Signup and view all the answers

    Which water-soluble vitamin is stored in the liver?

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

    Which property of water-soluble vitamins necessitates a regular dietary supply?

    <p>Their deficiency manifestation occurs rapidly due to no storage in the body.</p> Signup and view all the answers

    What is a characteristic of the structure of vitamin C (ascorbic acid)?

    <p>It is formed of 6-carbon atoms and resembles monosaccharides.</p> Signup and view all the answers

    Study Notes

    Nucleic Acids

    • Nucleic acids are polymers composed of monomers called nucleotides.
    • Nucleotides are referred to by single letter abbreviations: A, C, G, T, and U.
    • DNA contains A, C, G, and T, while RNA contains A, C, G, and U.

    Chemical Structure of Nucleic Acids

    • Nucleic acids are linear chains composed of nucleotides.
    • Each nucleotide consists of a base, a sugar, and a phosphate.
    • Sugars and phosphates form the backbone, while bases are attached as side chains to the sugars.

    Phosphate Group

    • Phosphate groups carry a negative charge at normal pH.

    Sugars

    • Ribose
    • Deoxyribose

    Nucleic Acids

    • ATP, GTP, UTP, and CTP are essential ribonucleotides functioning as coenzymes.
    • Nucleotides are components of nucleic acids.
    • Ribonucleotides are important for DNA replication and repair, and RNA synthesis.
    • ATP serves as a source of free energy for all cellular activities.

    Deoxyribonucleic Acid (DNA)

    • DNA consists of two long strings of nucleotides twisted around each other to form a spiral structure.
    • The sequence of bases within the backbone of DNA determines which proteins are being synthesized and in what order.

    Vitamins

    • Vitamins are organic compounds occurring in natural foods, required in minute amounts for normal growth, nutrition, and reproduction.
    • Vitamins are characterized by:
      • Being essential factors that must be supplied in the diet.
      • Being needed in small quantities for normal growth and maintenance.
      • Being required for proper utilization of carbohydrates, lipids, and proteins.
      • Not being oxidized to produce energy.
      • Deficiencies resulting in various metabolic diseases.
      • Being used in many chemical reactions inside the body, acting as catalysts.

    Causes of Vitamins Deficiencies

    • Inadequate dietary intake
    • Malabsorption
    • Increased requirements
    • Increased excretion
    • Treatment with some drugs

    Classification of Vitamins

    • Fat-soluble vitamins: A, D, E, and K
    • Water-soluble vitamins: C and B complex

    Fat Soluble Vitamins

    • Absorbed as lipid, requiring bile salts for absorption
    • Transported in the blood by carrier proteins
    • Stored in the liver for varying periods of time
    • Not excreted in urine, tending to accumulate in tissue
    • Deficiency manifestation occurs only when stores are depleted
    • Toxicity can occur with excessive intake

    Vitamins A "Retinoid"

    • Chemical structural: retinoid
    • 7-dehydrocholesterol is the precursor of vitamin D
    • Vitamin D is synthesized by the body upon exposure to sunlight

    Vitamin D

    • Stable in food, unaffected by storage and cooking
    • Milk is a poor source of vitamin D3
    • Daily requirements: 25-hydroxy-vitamin D

    Vitamin E

    • Antioxidant function:
      • Protection of RBCs from hemolysis
      • Enhancement of the immune response
      • Reduction of the risk of myocardial infarction
      • Protection against hepatic necrosis and damage of lung tissues
      • Slowing down the process of aging
    • Essential for fertility in animals, but not in humans

    Water Soluble Vitamins

    • Include vitamin C and vitamin B complex
    • Polar hydrophilic molecules, soluble in water
    • No stable storage form inside the body, requiring continuous dietary supply
    • Excreted in urine once concentrations exceed the renal threshold
    • Rare toxicities
    • Serve as coenzymes or cofactors in enzymatic reactions
    • Deficiency manifestation occurs rapidly

    Vitamin C "L-Ascorbic acid"

    • Structure resembles that of monosaccharides, with 6-carbon atoms
    • Present as L and D forms, with only L-ascorbic acid being active

    Deficiency of Vitamin B12

    • Extremely rare, but can occur in:
      • Vegetarians
      • Malabsorption
      • Elderly subjects with malfunctioning gastric parietal cells

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    Description

    Learn about the building blocks of nucleic acids, including DNA and RNA. Understand the composition of nucleotides and their differences in DNA and RNA.

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