Discovery of DNA Structure Quiz
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Questions and Answers

What did Rosalind Franklin's X-Ray Crystallography of DNA reveal in the 1950s?

  • The amount of adenine equals the amount of thymine
  • The double ring structure of purines
  • The base pairs are held together by hydrogen bonds
  • A regular and repetitive pattern (correct)

    • What rule did Edwin Chargaff find to be true for all species when analyzing DNA samples?

  • The amount of adenine equals the amount of thymine (correct)
  • Adenine and thymine have two hydrogen bonds
  • Cytosine and guanine have three hydrogen bonds
  • Purines have a double ring structure

    • What is the structural difference between purines and pyrimidines?

  • Purines have a double ring structure, while pyrimidines have a single ring structure (correct)
  • Purines have three hydrogen bonds, while pyrimidines have two hydrogen bonds
  • Purines have two hydrogen bonds, while pyrimidines have one hydrogen bond
  • Purines have a single ring structure, while pyrimidines have a double ring structure

    • How are the base pairs held together in DNA?

    <p>By hydrogen bonds</p> Signup and view all the answers

    What role do hydrogen bonds play in DNA replication?

    <p>They allow for the DNA strands to be easily separated during the replication process</p> Signup and view all the answers

    If a DNA sample is analyzed and 22% is cytosine, how much thymine would you expect in the sample?

    <p>28%</p> Signup and view all the answers

    What did Watson and Crick combine to create the first 3D, double helix model of DNA?

    <p>Findings of Franklin and Chargaff</p> Signup and view all the answers

    What are the key features of DNA structure according to the text?

    <p>Double stranded helix with sugar-phosphate backbone and nucleotides pairing</p> Signup and view all the answers

    Where is DNA found in eukaryotic cells according to the text?

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

    What are plasmids primarily found in, according to the text?

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

    What can be done with plasmids in laboratories according to the text?

    <p>Plasmids can be manipulated by removing them from bacteria and inserting a gene of interest to form recombinant plasmid DNA</p> Signup and view all the answers

    Which of the following scientists performed X-Ray Crystallography of DNA in the 1950s?

    <p>Rosalind Franklin</p> Signup and view all the answers

    What is the number of hydrogen bonds between adenine and thymine in DNA?

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

    Which statement accurately describes the nucleotide structure of purines and pyrimidines?

    <p>Purines have a double ring structure, while pyrimidines have a single ring structure</p> Signup and view all the answers

    How did Edwin Chargaff's analysis of DNA samples contribute to our understanding of DNA composition?

    <p>He found that the amount of adenine equals the amount of cytosine in DNA samples</p> Signup and view all the answers

    In DNA, what holds the base pairs together?

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

    What role do hydrogen bonds play in DNA replication?

    <p>They facilitate the separation of the DNA strands during replication</p> Signup and view all the answers

    What is the primary source of heritable information in some viruses, as mentioned in the text?

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

    In prokaryotic cells, where is DNA found according to the text?

    <p>Nucleoid region</p> Signup and view all the answers

    Which of the following statements about plasmids is true?

    <p>Plasmids can be manipulated in laboratories</p> Signup and view all the answers

    What are the key differences between RNA and DNA, as mentioned in the text?

    <p>RNA has uracil while DNA has thymine</p> Signup and view all the answers

    What was Chargaff's rule, as mentioned in the text?

    <p>$A=T$ and $C=G$</p> Signup and view all the answers

    What comprises the backbone of DNA, as mentioned in the text?

    <p>Sugar-phosphate</p> Signup and view all the answers

    What type of bond holds together nucleotides, as mentioned in the text?

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

    What are plasmids primarily found in?

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

    Which statement about DNA structure is true based on the text?

    <p>One DNA strand runs 5' to 3', other strand runs 3' to 5'</p> Signup and view all the answers

    What did Watson and Crick combine to create the first 3D, double helix model of DNA?

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

    Study Notes

    DNA Structure and Composition

    • Rosalind Franklin's X-Ray Crystallography of DNA in the 1950s revealed the double helix structure of DNA
    • Edwin Chargaff's analysis of DNA samples revealed that the amount of adenine (A) is always equal to the amount of thymine (T), and the amount of guanine (G) is always equal to the amount of cytosine (C)
    • This rule, known as Chargaff's rule, applies to all species and is essential for the replication of DNA

    Base Pairs and Hydrogen Bonds

    • The structural difference between purines (A and G) and pyrimidines (T and C) is that purines are larger and double-ringed, while pyrimidines are smaller and single-ringed
    • Adenine (A) always pairs with Thymine (T) and Guanine (G) always pairs with Cytosine (C) to form base pairs
    • Hydrogen bonds hold the base pairs together, with two hydrogen bonds between A and T and three hydrogen bonds between G and C
    • Hydrogen bonds play a crucial role in DNA replication by allowing the double helix to unwind and separate

    DNA Components and Location

    • DNA is found in the nucleus of eukaryotic cells and in the cytoplasm of prokaryotic cells
    • Plasmids are primarily found in bacteria and are small, self-replicating circular DNA molecules
    • Plasmids can be used in laboratories to manipulate DNA, introduce genes into cells, and study gene expression

    Historical Contributions

    • Rosalind Franklin performed X-Ray Crystallography of DNA in the 1950s
    • Watson and Crick combined Franklin's X-Ray Crystallography data with Chargaff's rule to create the first 3D, double helix model of DNA

    DNA Properties and Facts

    • If a DNA sample contains 22% cytosine, it would expect to have 28% guanine and 50% adenine and thymine combined
    • The backbone of DNA is comprised of sugar molecules (deoxyribose) and phosphate groups
    • Nucleotides are held together by phosphodiester bonds

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    Description

    Test your knowledge about the discovery of DNA structure in the 1950s, including the contributions of Rosalind Franklin's X-ray crystallography and Edwin Chargaff's findings on DNA samples from different species.

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