Hershey-Chase Experiment Quiz
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Questions and Answers

Who conducted the experiment that clarified the events leading to phage reproduction?

  • Alfred Hershey and Martha Chase (correct)
  • Louis Pasteur and Robert Koch
  • James Watson and Francis Crick
  • Charles Darwin and Gregor Mendel

    • What two components were established as having independent functions in the reproduction process of phages?

  • Phage protein and bacterial membrane
  • Nucleic acid and phage protein (correct)
  • Enzymes and nucleic acid
  • Bacterial DNA and proteins

    • The Hershey-Chase experiment was conducted in 1962.

    False

    Phage nucleic acid plays a dependent role in the phage reproduction process.

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

    What type of virus did the Hershey-Chase experiment focus on?

    <p>T-even bacteriophage</p> Signup and view all the answers

    What is the role of phage protein in reproduction?

    <p>It has an independent function in the reproduction process.</p> Signup and view all the answers

    In the Hershey-Chase experiment, the primary focus was on the events leading to __________ reproduction.

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

    Phage reproduction is associated with the bacterial cell and involves both ______ and nucleic acid functioning independently.

    <p>phage protein</p> Signup and view all the answers

    Match the following concepts related to the Hershey-Chase experiment with their descriptions:

    <p>T-even bacteriophage = A type of virus used in the experiment Lytic cycle = A method of viral reproduction Transduction = A process in which DNA is transferred by viruses Hershey-Chase experiment = Clarified phage reproduction events</p> Signup and view all the answers

    Match the components with their roles in phage reproduction:

    <p>Phage protein = Independent function in reproduction Nucleic acid = Independent function in reproduction Bacterial cell = Host for reproduction Phage = Virus that infects bacteria</p> Signup and view all the answers

    What are the main components of T2 phages?

    <p>50 percent protein and 50 percent DNA</p> Signup and view all the answers

    What serves as the genetic material in phages synthesized in a test tube?

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

    T2 phages initiate infection by binding to bacterial cells through their tail fibers.

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

    RNA synthesized in a test tube directs the production of components necessary for viral reproduction.

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

    What percentage of T2 phages is composed of protein?

    <p>50 percent</p> Signup and view all the answers

    T2 phages infect bacterial cells by adsorption through their ______ fibers.

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

    What type of material is necessary for the reproduction of phages?

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

    Match the following terms with their descriptions:

    <p>T2 phages = Consist of 50% protein and 50% DNA Tail fibers = Used for adsorption to bacterial cells Infection initiation = Begins when the phage binds to bacteria Bacterial cells = The host for T2 phages</p> Signup and view all the answers

    In phages, RNA directs the production of all the components necessary for __________ reproduction.

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

    Match the following components with their roles in viral reproduction:

    <p>RNA = Genetic material Viral components = Produced based on RNA direction Test tube synthesis = Environment for RNA creation Phages = Type of virus</p> Signup and view all the answers

    What type of bonds are formed between nitrogenous bases of opposite chains in DNA?

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

    Nitrogenous bases in DNA are paired through ionic bonds.

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

    What is the role of hydrogen bonds in the structure of DNA?

    <p>They pair nitrogenous bases of opposite chains.</p> Signup and view all the answers

    In DNA, the ______ bases are paired as the result of the formation of hydrogen bonds.

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

    Match the following nitrogenous bases with their complementary pairs:

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

    What is the degree of rotation for base pairs in DNA?

    <p>34.6°</p> Signup and view all the answers

    Hydrogen bonds are a type of covalent bond between bases.

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

    What type of bond is formed between sugar and phosphate in DNA?

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

    The bond between sugar and base is known as a _______ bond.

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

    Match the types of bonds with their descriptions:

    <p>Hydrogen bonds = Between nitrogenous bases Phosphodiester bonds = Between sugar and phosphate Glycosidic bonds = Between sugar and base</p> Signup and view all the answers

    Study Notes

    Introduction to Biochemical Genetics

    • Biochemical genetics examines the structure and function of the genetic material.
    • It focuses on DNA, RNA, and their interaction within cells.

    DNA Structure and Analysis

    • DNA is the genetic material in most living organisms, except for some viruses.
    • The Watson-Crick model describes DNA as a right-handed double helix.
    • The double helix strands are antiparallel, held together by hydrogen bonds between complementary bases.
    • DNA's structure enables the storage and expression of genetic information.
    • RNA, similar to DNA, exists primarily as a single-stranded molecule.
    • Some viruses employ RNA as genetic material.
    • Nucleic acid analysis often involves detecting complementary nitrogenous bases.

    Characteristics of Genetic Material

    • Genetic material must exhibit replication, storage of information, expression of information, and mutation.

    Cell Cycle

    • Cells progress through stages of interphase (G1, S, G2) and mitosis to divide.
    • Following mitosis, cells enter G1 for a new cycle.
    • Cells can become non-dividing (G0).
    • The cycle includes DNA synthesis (S phase), and the phases of mitosis (M phase) to produce two daughter cells.

    Information Flow (Central Dogma)

    • Information flows from DNA to RNA to protein.
    • Replication, transcription, and translation are key steps.
    • DNA serves as a template for RNA synthesis.
    • mRNA carries the genetic code for protein synthesis.
    • Ribosomes translate mRNA into proteins, with tRNA assisting in amino acid delivery.

    Evidence Favoring DNA as Genetic Material

    • Early observations favored protein as the genetic material.
    • Studies of bacteria and bacteriophages later revealed DNA as the genetic material.
    • Griffith's experiment (1927) on bacterial transformation highlighted the importance of cellular uptake of DNA for phenotypic change.
    • Avery, MacLeod, and McCarty's experiment (1944) identified DNA as the transforming principle in bacteria.
    • Hershey-Chase experiment (1952): Phage genetic material is DNA, not protein.
    • Transduction experiments demonstrate that DNA, not protein, is transferred via viruses.
    • Transfection experiments, using protoplasts, demonstrated that viral infection could occur with disrupted viruses.

    Indirect and Direct Evidence of DNA as Eukaryotic Genetic Material

    • Studying the DNA content of various organisms (eukaryotes) using various methods, like estimating DNA content in different cell types to support that DNA is the genetic material.
    • Recombinant DNA technology: Evidence that DNA can be manipulated and used to transfer genetic information between species.

    DNA Structure (Chemical Properties)

    • DNA is composed of nucleotides: a nitrogenous base, deoxyribose sugar, and phosphate group
    • Purines (adenine and guanine) and pyrimidines (thymine and cytosine).
    • Uracil replaces thymine in RNA.
    • Nucleotides link via phosphodiester bonds to form polynucleotide chains.
      • The 5' end phosphate and 3' hydroxyl groups play a significant role in DNA polymer construction.
      • These patterns, which include the stacking force, the hydrogen bonds, and the phosphodiester chemical bonds, are key elements in creating DNA structure and function.

    Base Composition Studies

    • Chargaff's rule: In DNA, amount of adenine equals thymine, and amount of guanine equals cytosine
    • X-ray diffraction analysis (Rosalind Franklin): Crucial in determining DNA's double helix structure.
    • Base composition studies confirm DNA's role in genetic material and function.

    The Watson-Crick Model

    • Two polynucleotide chains form a right-handed double helix around a central axis.
    • The strands are antiparallel (opposite directions).
    • The bases are flat structures, perpendicular to the axis; stacked on each other within the helix.
    • Bases pair via hydrogen bonds.

    RNA as Genetic Material in Some Viruses

    • Certain viruses utilize RNA as their genetic material (retroviruses).
    • Retroviruses employ reverse transcription to convert RNA into DNA.
    • The human immunodeficiency virus (HIV) is an example of a retrovirus.

    Biochemical Techniques

    • Various biochemical techniques exist for isolating, characterizing, and manipulating nucleic acids (DNA and RNA).
    • These techniques are instrumental in genetic research and testing.

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    Biochemical Genetics PDF - Lecture Notes

    Description

    Test your knowledge on the Hershey-Chase experiment and its significance in understanding phage reproduction. Explore key concepts such as the roles of nucleic acids and proteins in the reproduction process of T2 phages. This quiz will cover essential components and their independent functions in phage life cycles.

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