18 Questions
What was the significance of Wilhelm Johanssen's and Herman Nilsson-Ehle's experiments in broad beans and wheat?
They provided evidence for the particulate inheritance of traits.
What did Thomas Morgan's experiments on Drosophila establish?
The role of chromosomes in heredity and the phenomenon of crossing over.
What was the result of the Avery – MacCleod – Mc Carthy Experiment in 1944?
It established DNA as the genetic material.
What did Harriet Creighton and Barbara Mcclintock's experiments in 1931 demonstrate?
Genetic recombination is caused by a physical exchange of chromosomal pieces.
What was the focus of the Eugenics Movement in the 1910's-30's?
Improving the human race through selective breeding.
What was the significance of Fred Griffith's experiment in 1928?
It showed that some component of heat-killed virulent bacteria can transform a non-virulent strain.
What is the key idea behind the Particulate Inheritance Theory proposed by Pierre Louis Maupertuis?
Minute particles from each body part combine to form a new individual.
What was the main idea of the 'Theory of Preformation'?
The idea that sex cells contain a complete miniature of an adult
What was the main criticism of Charles Darwin's Theory of Pangenesis?
It did not explain how acquired characters are inherited.
Who is credited with the theory of Epigenesis?
William Harvey
What was the significance of August Weismann's experiment with mice?
It demonstrated that the absence of tails in parents does not result in tailless offspring.
What is the significance of Gregor Mendel's work in the development of genetic theory?
He developed the first genetic theory based on statistical analysis.
What was Aristotle's view on the role of semen in reproduction?
It was a highly purified fluid from the blood
Who is credited with coining the term 'genetics'?
William Bateson
What was the main contribution of Casper Wolff to the development of genetic theory?
He provided experimental evidence against the Theory of Preformation
What is the significance of the records of pedigrees of domesticated animals and crop plants from 6,000 years ago?
They are early evidence of the practice of selective breeding
What was the significance of Friedrich Miescher's discovery in 1869?
He identified the genetic material in cell nuclei.
Which of the following is NOT a theory of inheritance discussed in the text?
Lamarckism
Study Notes
Early Records of Genetics
- 6,000 years ago, records of pedigrees of domesticated animals (horses, dogs, camels, sheep) and crop plants (wheat, rice, maize, date palm) were kept.
The Greek Influence
- 400 B.C.: Hippocrates theorized that male seed is thicker or more solid, while female seed is more fluid.
- 500 B.C.: Aristotle believed in the "vital heat fluid" (SEMEN), which was considered highly purified blood.
- 500 B.C.: Pythagoras proposed the "Fluids & Vapors" Theory, where vapors from various organs unite to form individuals.
Era of Awakening (17th Century)
- Jan Swammerdam proposed the Theory of Preformation, suggesting that sex cells contain a complete miniature of an adult (homunculus).
Era of Awakening (17th Century)
- William Harvey introduced Epigenesis, suggesting that an organism develops from substances present in the egg that differentiate into adult structures during embryonic development.
Era of Awakening (18th Century)
- Casper Wolff disagreed with the Theory of Preformation and provided experimental evidence that no preformed embryo existed in the chicken egg.
- Pierre Louis Maupertuis proposed the Particulate Inheritance Theory, where minute particles from each body part unite in sexual reproduction to form a new individual.
Era of Awakening (19th Century)
- Charles Darwin introduced the Theory of Pangenesis, suggesting that each body part produces minute particles (gemmules) that unite in the reproductive organs to form offspring with blended characteristics.
- August Weismann disproved the Theory of Pangenesis through an experiment involving cutting the tails of mice and observing the offspring.
Era of Awakening (19th Century)
- Gregor Mendel proposed the Four Postulates: Unit Factors in Pairs, Dominance/Recessiveness, Segregation, and Independent Assortment.
- Friedrich Miescher identified DNA (initially called "nuclein") as an acidic substance found in cell nuclei.
Era of Awakening (20th Century)
- William Bateson coined the term "genetics" in 1905.
- Wilhelm Johanssen and Herman Nilsson-Ehle conducted experiments on quantitative traits in broad beans and wheat.
Era of Awakening (20th Century)
- Thomas Morgan conducted experiments on Drosophila (fruit flies) and discovered that genes are carried on chromosomes and provided the mechanical basis for heredity.
- The eugenics movement emerged in the 1910s-30s, leading to involuntary sterilization laws.
Molecular Genetics
- 1928: Fred Griffith showed that a component of heat-killed virulent bacteria can "transform" a non-virulent strain to become virulent.
- The Avery – MacCleod – Mc Carthy Experiment proved that DNA is the genetic material.
- Karl Landsteiner discovered the ABO blood types.
- Harriet Creighton and Barbara Mcclintock demonstrated genetic recombination through physical exchange of chromosomal pieces in corn.
Test your knowledge of early theories of inheritance, including the Particulate Inheritance Theory and the Theory of Pangenesis, proposed by Pierre Louis Maupertuis and Charles Darwin respectively. Learn about the concept of gemmules and pangenes in the 18th and 19th centuries.
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