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    Timelines – Genetics

    Pre-modern Era
    1. The ‘Blending’ Hypothesis
    Double asterisk: Theory of Pangenesis (500 BCE – early 19th century): Ancient Greeks including Hippocrates and Aristotle believed in a concept known as “pangenesis,” where particles called “gemmules” representing every organ and tissue in the body blend together, and characteristics of progeny are determined by this mix. This concept remained dominant until the 19th century.

    Modern Era
    2. The Birth of Modern Genetics
    Double asterisk: Gregor Mendel’s Experimental Work (1856 – 1863): Austrian monk Gregor Mendel performed experiments on pea plants, carefully observing the inheritance of traits. His pioneering work on “Mendelian inheritance” became the bedrock for our understanding of modern genetic science.

    3. The Rediscovery of Mendel’s Work
    Double asterisk: Establishment of Mendelian Principles (1900): Three scientists, Hugo de Vries, Carl Correns, and Erich Tschermak independently rediscovered Mendel’s work years after his death, leading to the grounding principles of genetics.

    4. The Chromosome Theory
    Double asterisk: The Sutton-Boveri Theory (1902-1903): Walter Sutton and Theodor Boveri independently proposed that chromosomes, not the cell nucleus, are responsible for Mendelian inheritance. This became known as the Chromosome Theory of Inheritance.

    5. The Concept of Genes
    Double asterisk: Thomas Hunt Morgan’s Work (1915): By studying fruit flies, Thomas Hunt Morgan confirmed that chromosomes carry genetic material. He subsequently proposed the concept of “genes” – specific segments on chromosomes that determine traits.

    Post-Modern Era
    6. The DNA Revolution
    Double asterisk: Identification of DNA as Genetic Material (1944): Oswald Avery, Colin MacLeod, and Maclyn McCarty identified that DNA is the chemical basis of heredity, debunking previous belief that proteins were the genetic material.

    7. The Double Helix
    Double asterisk: Discovery of Structure of DNA (1953): James Watson and Francis Crick unraveled the double helix structure of DNA, a groundbreaking breakthrough in understanding how genetic information is stored and transferred.

    8. The Genetic Code
    Double asterisk: Cracking the Genetic Code (1960s): Scientists including Marshall Nirenberg, Har Gobind Khorana, and Robert W. Holley deciphered the genetic code, illuminising how DNA directs protein synthesis.

    9. Genetic Engineering
    Double asterisk: Development of Recombinant DNA technology (1973): Stanley Cohen and Herbert Boyer invented recombinant DNA technology, enabling the manipulation and combination of DNA from different organisms, heralding the era of genetic engineering.

    Contemporary Era
    10. The Entire Human Genome
    Double asterisk: Human Genome Project (1990 – 2003): The international scientific research project aimed to determine the sequence of nucleotide base pairs which make up human DNA, and researching the physical and functional units of genes. The completion of Human Genome Project holds enormous potential in fields like medicine and human evolution.

    11. The Dawn of CRISPR
    Double asterisk: Invention of CRISPR-Cas9 (2012): Jennifer Doudna and Emmanuelle Charpentier pioneered the development of CRISPR-Cas9, a revolutionary genome editing tool that substantially enhances precision and scalability of genetic modification.