Molecular Biology: Meselson and Stahl (1959)
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Questions and Answers

Who demonstrated a direct link between chromosomes and hereditable factors in 1911?

  • James Watson
  • Charles Darwin
  • Frederick Griffith
  • Thomas Morgan (correct)
  • What did Thomas Morgan propose based on his observations of white eyes in males?

  • That white eyes are a result of random mutation
  • That the white eye trait is linked to a specific gene
  • That chromosomes determine eye color
  • That sex chromosomes determine the white eye trait (correct)
  • What is the term used to describe the concept discovered by Frederick Griffith in 1928?

  • The molecular model
  • The transforming principle (correct)
  • The genetic code
  • The central dogma
  • What type of molecule is likely to be involved in the transforming principle?

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

    What is the role of chromosomes according to Thomas Morgan's work?

    <p>To carry genetic information</p> Signup and view all the answers

    What is a key concept related to chromosomes and hereditary traits?

    <p>Sex-linked traits</p> Signup and view all the answers

    What is the significance of Thomas Morgan's work in the context of molecular biology?

    <p>It showed the link between chromosomes and hereditary traits</p> Signup and view all the answers

    What is the underlying idea behind Thomas Morgan's work and Frederick Griffith's discovery?

    <p>Genetic information is carried on chromosomes</p> Signup and view all the answers

    What is the name of the replication model proposed by Meselson and Stahl in 1959?

    <p>Semi-conservative replication</p> Signup and view all the answers

    Who contributed to the discovery of the genetic code in 1965?

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

    What was the significance of Fred Sanger's work in 1977?

    <p>He developed a method for DNA sequencing</p> Signup and view all the answers

    What is the relationship between genome size and organism complexity in eukaryotes?

    <p>There is a remarkable lack of correspondence between the two</p> Signup and view all the answers

    Who sequenced the human genome in 2001?

    <p>Craig Venter</p> Signup and view all the answers

    What is the relationship between the number of protein-coding genes and organism complexity?

    <p>There is a remarkable lack of correspondence between the two</p> Signup and view all the answers

    Which of the following scientists did not contribute to the discovery of the genetic code?

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

    What was the significance of the work of Meselson and Stahl in 1959?

    <p>They provided evidence for the semi-conservative replication model of DNA</p> Signup and view all the answers

    Who is credited with the discovery of cells?

    <p>Robert Hooke</p> Signup and view all the answers

    What is the fundamental theory of heredity according to Mendel's principles of inheritance?

    <p>Inheritance involves the passing of discrete units of inheritance</p> Signup and view all the answers

    What is the process called during which the inherited factors that determine traits are separated into reproductive cells?

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

    What is the principle of independent assortment according to Mendel's principles of inheritance?

    <p>Units of inheritance located on different 'places' will be inherited independently of each other</p> Signup and view all the answers

    Who formulated the cell theory?

    <p>Matthias Schleiden and Theodor Schwann</p> Signup and view all the answers

    What is the third principle of the cell theory?

    <p>Cells can arise from pre-existing cells</p> Signup and view all the answers

    What is the basic unit of structure and organization in organisms according to the cell theory?

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

    Who is known for setting up the rules to understand heredity?

    <p>Gregor Mendel</p> Signup and view all the answers

    Study Notes

    Key Discoveries in Molecular Biology

    • Robert Hooke (1665) discovered cells, which were initially referred to as "monastic cells".
    • Matthias Schleiden and Theodor Schwann (1839) formulated the cell theory, which states that:
      • All living organisms are composed of one or more cells.
      • The cell is the basic unit of structure and organization in organisms.
      • Cells arise from pre-existing cells.

    Mendel's Principles of Inheritance

    • Gregor Mendel (1865) set up the rules to understand heredity (genetics) and established three principles:
      • The fundamental theory of heredity, which states that inheritance involves the passing of discrete units of inheritance (now known as genes) from parents to offspring.
      • The principle of segregation, which states that during reproduction, the inherited factors that determine traits are separated into reproductive cells by a process called meiosis and randomly reunite during fertilization.
      • The principle of independent assortment, which states that "units of inheritance" located on different "places" will be inherited independently of each other.
    • Thomas Morgan (1911) demonstrated a direct link between chromosomes and heritable factors, and showed that:
      • Some traits are sex-linked.
      • The white trait was probably carried on one of the sex chromosomes.
      • Other genes were probably carried on specific chromosomes as well.

    The Transforming Principle

    • Frederick Griffith (1928) discovered the "transforming principle", which involves the transfer of genetic information from one bacterium to another.

    Semi-Conservative Replication

    • Meselson and Stahl (1959) demonstrated semi-conservative replication, which is a key mechanism of DNA replication.

    The Genetic Code

    • Crick, Brenner, Barnett, and Watts-Tobin (1965) contributed to the discovery of the genetic code, which is the set of rules that dictates how genetic information is translated into proteins.
    • Marshall Nirenberg and Heinrich J. Matthaei also contributed to the discovery of the genetic code.

    DNA Sequencing

    • Fred Sanger (1977) developed a method for DNA sequencing, which allows for the determination of the order of nucleotide bases in a DNA molecule.
    • Craig Venter (2000) led the effort to sequence the Drosophila genome, and later (2001) led the effort to sequence the human genome.

    Genomes

    • There is a remarkable lack of correspondence between genome size and organism complexity, especially among eukaryotes.
    • There is also a lack of correspondence between the number of protein-coding genes and organism complexity.

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    Description

    This quiz assesses your understanding of Meselson and Stahl's 1959 experiment on semi-conservative replication, a fundamental concept in molecular biology.

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