Mid to Late 19th Century
The origins of genetics lie in the development of theories of evolution. It was in 1858 that the
origin of species and how species variability was developed after the research work of Charles
Darwin and Wallace. They described how new species arose via evolution and how natural
selection occurred to evolve new forms. They however did not know the role genes had to play
in this phenomenon.
Around the same time Gregor Mendel, an Austrian monk, was performing extensive experiments
on inheritance and genetics of sweet pea plants. He described the unit of heredity as a particle
that does not change and is passed on to offspring. His work is in fact the basis of understanding
the principles of genetics even today. Consequently, Gregor Mendel is known as the Father of
Genetics. There was, however, little awareness of Gregor’s work during this time.
Also in this period Haeckel correctly predicted that the heredity material was located in the
nucleus. Miescher showed the material in the nucleus was a nucleic acid. Chromosomes as units
carrying genetic information was also discovered around this time.
Early 20th Century
It was during this time that the Mendelian Principles and the Chromosomal Theory of
Inheritance was established. Mendel’s work was largely unknown. It was not until 1900 that
there was a rediscovery of the Mendelian principles and publications began citing his work.
Development of the chromosomal theory led to advent of the field of cytogenetics. The first
observations of chromosomal abnormalities (e.g. duplications, deletions, translocations,
inversions) were reported around this time.
Mid 20th Century
It was in 1870s that the material in the nucleus was determined to be a nucleic acid. DNA was
determined to be the genetic material between 1920s and mid-1950s. Griffith’s experiments with
a bacterial strain established the theory.
Avery, MacLeod and McCarty further showed that DNA, not protein or RNA was the factor
responsible for genetic inheritance and evolution of the bacterial strains studied by Griffith.
It was then that Watson and Crick in their groundbreaking work determined the structure of
DNA, and others suggested that DNA contained a genetic code. The code was discovered in the
1960’s. Crick discovered the process of transcription and translation and led to formation of the
“central dogma of molecular biology”.
Mid-late 20th Century and the Early 21st Century
This period heralded the concept of molecular biology and molecular genetics. Various advanced
technologies made their way into knowledge base around this time. This included molecular
biology, recombinant DNA technology, and biotechnology methods.
Methods of radiolabelling of the DNA with radioactive or fluorescent tags for development of
diagnostic and therapeutic methods as well as research tools were discovered during this time.
Restriction enzymes were discovered and used to construct recombinant DNA molecules that
contained foreign DNA that could be grown in abundance in bacterial strains.
Then came methods like PCR (Polymerase chain reaction) and host of other biotechnology
methods and new applications were found in medicine, pharmacotherapeutics as well as
research.
Mid to Late 19th Century: Evolution, Natural Selection, Particulate Inheritance and
Nuclein 1858
Darwin and Wallace - Role of natural variation and natural selection in evolution
1865 - Gregor Mendel - Particulate inheritance
1866 - Ernst Haeckel; Heredity materials was in the nucleus
1871 - Friedrich Miescher; Material in the nucleus was a nucleic acid
Early 20th Century: Mendelian Principles are extended and the Chromosomal Theory of
Inheritance solidifies
1900 - Correns, de Vries, von Tschermak - Mendel’s work is rediscovered;The age of
genetics begins
1902 - Walter Sutton and Theodor Boveri - Chromosomal Theory of Inheritance; The
heredity material resides in chromosomes
1905-1923
Linkage
Sex linkage
Genetic mapping
Number of linkage groups - number of chromosomes
Lethal genes
Maternal inheritance
1908 - Hardy and Weinberg - Hardy-Weinberg principle of genetic equilibrium
1909 - Nilsson-Ehle - Theory of quantitative traits and quantitative genetics
Mid 20th Century: DNA is the stuff of life; the preeminence of the Darwinian theory of
evolution via natural selection is confirmed
1928 - Griffith - Transformation experiments
1944 - Avery, MacLeod, McCarty - Definitive proof that DNA is the genetic material
1953 - Watson and Crick - DNA structure is defined
1954-1961
DNA code is determined
Transcription is described
Replication is described
Translation is described
Operons are discovered
1932-1953
Fisher and Dobzhansky - The Modern Synthesis is formulated
Links Darwinian evolutionary theory and Mendelian genetics
1968
Kimura
Neutral Theory of Molecular Evolution is introduced
Mid-late 20th Century and the Early 21st Century: The Age of Molecular Genetics;
Phylogenetics Studies Intensive; The Information Age; The Emergence of Genomics
Science
1969 - ARPANET - Internet comes on line
1970 - Arber and Smith - First restriction enzyme, Hind II, is isolated
1970 - Baltimore and Temin - Discovery of reverse transcriptase
1972 - Berg - First recombinant DNA molecule is constructed
1973 - Boyer and Cohen - First functional recombinant E. coli cell produced
1977 - Sanger and Gilbert - DNA sequencing techniques are described
1977 - Sharp and Roberts - Introns discovered
1978 - Botstein - RFLPs launch the era of molecular mapping of linkage groups
1980 - Sanger Group - First genome is sequenced, the bacteriophage ΦX174 of E. coli
1983 - Mullis - PCR technique is discovered
1986 - Hood, Smith, Hunkapiller and Hunkapiller - First automated DNA sequencer
1990 - US Government - Human Genome Project launched
1995 - Celera - First bacterial genome (H. influenza) is sequenced
1996
Yeast Genome Consortium
First eukaryotic genome (yeast) sequenced
2000 - Arabidopsis Genome Initiative - First flowering plant genome (Arabidopsis
thaliana) is sequenced
2001 - The human genome sequence is published
