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

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

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

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

<p>Sex-linked traits (B)</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 (A)</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 (D)</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 (C)</p> Signup and view all the answers

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

<p>All of the above (D)</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 (D)</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 (C)</p> Signup and view all the answers

Who sequenced the human genome in 2001?

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

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

<p>Venter (B)</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 (D)</p> Signup and view all the answers

Who is credited with the discovery of cells?

<p>Robert Hooke (B)</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 (B)</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 (C)</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 (C)</p> Signup and view all the answers

Who formulated the cell theory?

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

What is the third principle of the cell theory?

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

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

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

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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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