DNA Structure and Components
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Questions and Answers

What is the primary component of DNA?

  • Adenine
  • Histones
  • Deoxyribonucleotides (correct)
  • Ribose
  • In which types of cells is DNA found?

  • Only in animal cells
  • In every nucleated cell (correct)
  • Only in bacteria
  • Only in plant cells
  • Which nitrogenous bases are classified as Purines?

  • Adenine and Thymin
  • Cytosine and Uracil
  • Adenine and Guanine (correct)
  • Thymine and Cytosine
  • What is the sugar component of DNA?

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

    What term was coined by Atlman for the protein-free preparation of nuclei?

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

    What makes the nitrogenous bases in DNA negatively charged?

    <p>Presence of phosphate groups</p> Signup and view all the answers

    How does a nucleoside form?

    <p>By the association of a sugar and a nitrogenous base</p> Signup and view all the answers

    Which other nitrogenous base complements Adenine in DNA?

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

    What type of bond links ribonucleotides together in RNA?

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

    Where does the phosphate group attach in a deoxyribonucleotide?

    <p>C-3'</p> Signup and view all the answers

    Which nucleotides serve as the building blocks for DNA?

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

    In a nucleic acid strand, which end is defined by a free hydroxyl group?

    <p>3-end</p> Signup and view all the answers

    What type of structural unit is a deoxyribonucleotide composed of?

    <p>Base, sugar, and phosphate</p> Signup and view all the answers

    Which atom in the nitrogenous base of a nucleotide is typically linked to the sugar?

    <p>N-1</p> Signup and view all the answers

    What kind of bond forms between the monosaccharide units of polysaccharides?

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

    Which functional group does the phosphate group attach to in a nucleic acid?

    <p>Hydroxyl group</p> Signup and view all the answers

    What is the primary structural difference between a dinucleotide and a polynucleotide?

    <p>A dinucleotide is formed from two nucleotide units, while a polynucleotide consists of many nucleotide units.</p> Signup and view all the answers

    What role do hydrogen bonds play in the structure of DNA?

    <p>They hold the complementary nitrogenous bases together.</p> Signup and view all the answers

    Which carbon of the sugar molecule in a nucleotide is bonded to the nitrogenous base?

    <p>The 1st carbon</p> Signup and view all the answers

    What feature distinguishes the arrangement of DNA strands in the double helix?

    <p>The strands are oriented in an antiparallel arrangement.</p> Signup and view all the answers

    Which of the following best defines a nucleotide?

    <p>A structure made of a nitrogenous base, sugar, and a phosphate group.</p> Signup and view all the answers

    What is considered the functionally important aspect of the order of bases in a polynucleotide?

    <p>It determines the genetic information of the molecule.</p> Signup and view all the answers

    What two scientists are credited with determining the three-dimensional structure of DNA?

    <p>Watson &amp; Crick</p> Signup and view all the answers

    In a nucleotide, what connects the 3rd carbon of one sugar to the 5th carbon of the next?

    <p>A phosphate group</p> Signup and view all the answers

    What is the relationship between Adenine and Thymine in DNA?

    <p>They pair with complementary bases.</p> Signup and view all the answers

    Which groove of the DNA double helix is wider and more accessible for protein binding?

    <p>The major groove.</p> Signup and view all the answers

    Which pair of bases is correctly matched according to Chargaff's Rule?

    <p>Guanine and Cytosine</p> Signup and view all the answers

    How many hydrogen bonds are formed between Adenine and Thymine?

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

    What structure do the glycosidic bonds between sugar and bases form in DNA?

    <p>They create unequal grooves.</p> Signup and view all the answers

    Which of the following statements about the backbone of DNA is true?

    <p>It is composed of deoxyribose and phosphodiester linkages.</p> Signup and view all the answers

    Why is the interaction of DNA-binding proteins more favorable with the major groove?

    <p>The major groove is less obstructed by the sugar-phosphate backbone.</p> Signup and view all the answers

    Which of the following is NOT true about the base pairing in DNA?

    <p>Base pairs can form in any arbitrary combination.</p> Signup and view all the answers

    What is the most common conformation of DNA?

    <p>B-DNA</p> Signup and view all the answers

    How many base pairs does one complete turn of the B-DNA double helix consist of?

    <p>10.4 base pairs</p> Signup and view all the answers

    What is the diameter of the B-DNA double helix?

    <p>2.37 nm</p> Signup and view all the answers

    In what condition is Z-DNA primarily seen?

    <p>High salt concentrations</p> Signup and view all the answers

    What type of molecules are prokaryotic DNA typically associated with?

    <p>Naked DNA</p> Signup and view all the answers

    What is the pitch of the A-DNA helix?

    <p>2.46 nm</p> Signup and view all the answers

    Which feature differentiates Z-DNA from B-DNA?

    <p>Z-DNA is a left-handed helix</p> Signup and view all the answers

    What is a feature of eukaryotic DNA compared to prokaryotic DNA?

    <p>It resides within a membrane-bound nucleus</p> Signup and view all the answers

    Study Notes

    DNA Structure

    • DNA is a polymer of deoxyribonucleotides found in chromosomes, mitochondria, and chloroplasts.
    • Nuclear DNA is bound to basic proteins called histones.
    • DNA is present in every nucleated cell and carries genetic information.
    • DNA is composed of two strands wound around each other to form a double helix with bases inside and sugar-phosphate backbones on the outside.
    • Two DNA strands are organized in an antiparallel arrangement.
    • The bases form hydrogen bonds to each other.
    • Adenine pairs with Thymine, and Guanine pairs with Cytosine. This is called complementary base pairing.

    DNA Components

    • Deoxyribose: A five-carbon sugar that forms the backbone of DNA.
    • Phosphate Group: A negatively charged group that links deoxyribose molecules together.
    • Nitrogenous Bases: Adenine, Guanine, Cytosine, and Thymine. Adenine and Guanine are purines; Thymine and Cytosine are pyrimidines.

    DNA Nucleotides

    • Nucleoside: A base bound to a sugar.
    • Nucleotide: A nucleoside bound to a phosphate group.
    • Deoxyribonucleotides: Nucleotides containing deoxyribose are the building blocks of DNA.
    • Ribonucleotides: Nucleotides containing ribose are the building blocks of RNA.

    DNA Structure Features

    • Double helix: DNA has two strands that wind around each other.
    • Antiparallel: The two strands of DNA have opposite orientations.
    • Major groove: A wider groove between the two strands of DNA.
    • Minor groove: A narrower groove between the two strands of DNA.
    • B-DNA: The most common conformation of DNA. It is a right-handed helix with one turn every 10.4 base pairs.
    • A-DNA: A right-handed helix that is wider and flatter than B-DNA. It is found in dehydrated conditions or low salt concentrations.
    • Z-DNA: A left-handed helix with one turn every 12 base pairs. It is found in high salt concentrations.

    DNA Polymorphism

    • DNA can exist in different conformations depending on conditions.

    Prokaryotic DNA

    • Found in bacteria and archaea.
    • Present as a single circular molecule called a bacterial chromosome.
    • DNA is naked (without associated histone proteins).

    Eukaryotic DNA

    • Found in more complex multicellular organisms like plants, animals, fungi, and single-celled organisms like amoeba and yeast.
    • Enclosed within a membrane-bound nucleus.
    • DNA is bound with histone proteins.

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    DNA Final Presentation PDF

    Description

    This quiz covers the fundamental structure of DNA, including its components such as deoxyribose, nitrogenous bases, and nucleotides. Understand how DNA forms a double helix and the significance of complementary base pairing. Test your knowledge of how these elements function together to carry genetic information.

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