1665 – Robert Hooke: discovered the cell in sections of cork. Observed cork cells and first to give drawings of cell and coined term “cell”. The term came from the Latin word cella which means "storeroom" or "small container". He documented his work in the Micrographia.
1674- Antony Van Leeuwenhoek: A Dutch cloth merchant, has a credit of improving microscopes/microscopic lenses. He improved microscopic lenses by glass grinding and magnification increased up to 300times.
1763 - J.G. Koelreuter: discovered quantitative inheritance by his observation that certain plant hybrids had characters intermediate between those of the two parents.
1831 – Rober Brown: discovered ‘Nucleus’ in flowering plants Tradecansia and showed that it was present in all cells. Studied the Brownian movement from cells.
1839-Theodor Schwann, Matthias Jakob Schleiden and Rudolf Virchow: Cell Theory-- Cell is the basic unit of life ( all living organisms both multicellular/unicellular) All cells arise from pre-existing cells Exceptions to the cell theory-- Mitochondria and chloroplasts are self replicating Viruses are not true cells
1841 – Robert Remak: described amitotic cell division in the RBC of the chick embryo.
1848 – W. Hofmeister: drew figures of chromosomes of the nuclei of pollen mother cells of Tradescantia.
1854 – R.Virchow: confirmed principle of cells arise from pre-existing cells and gave the dictum ‘omnis cellula a cellula’ (all cells arise from pre-existing cells).
1866 - E.Haeckel: put forword the hypothesis that the transmission of inheritance took place through the nucleus.
1866 - Gregor Mendel: formulated the laws of heredity by his now famous work on peas.
1875 – Van Beneden: observed the centriole.
1879 -1882– W. Flemming: --Termed ‘Mitosis’ and showed chromosomes split longitudinally during nucleus division and formation of daughter cells. described chromatin, the deeply staining part of the nucleus Developed improved staining and fixing methods
1881 – Balbiani: discovered giant salivary gland chromosomes.
1882 – W. Flemming: discovered chromomeres, the “granules” on chromosomes.
1883 - W.Roux: proposed the role of chromosomes in heredity.
1883-1885 August Weisman : First to differentiate between somatic and germ cells and proposed ‘germplasm/germ line theory’. Germplasm – involved in fertilization and transferred to next generation Somatoplasm- variations in this will not be transferred to next generation
1884- Edward Starsburger : Studied fertilization in angiosperms and observed that eggs carry more cytoplasm than sperm. He also noticed no differences in reciprocal crosses of different plant species and concluded that cytoplasm is not carrying any hereditary material to next generation. Discovered mitosis in palnts.
1885 - O. Hertwig and E. Sirasburger: proposed the role of the nucleus in heredity.
1887 – E. Van Beneden: demonstrated that the number of chromosomes was halved during gamete formation in Ascaris megalocephala and chromosome contribution of egg and sperm are numerically equal. The chromosome number is constant for each species.
1901 - Hugo de Vries: proposed the mutation theory of evolution on the basis of sudden appearance of new characters in the evening primrose Oenothera lamarckiana.
1902 - C.E.McClung: discovered sex chromosomes in the grasshopper.
1903 - W.Sutton: showed that in diploid cells chromosomes occur in homologous pairs.
1902 Walter Sutton and 1903 Boveri : Chromosomal theory of inheritance Independently both observed parallelism between behaviour of chromosomes and Mendelian factors as below, hence concluded that factors are present on chromosomes- both are present in pairs- Single dose in gametes- segregates during gamete formation- maintain their indentity/inviduality
1906 - W.Bateson and R. C. Punnett: discovered linkage of hereditary units.
1909 - F.A.Janssens: proposed the chiasmatype theory, according to which exchange of chromosomal segments of homologous chromatids takes place through chiasmata formation.
1910 - T. H. Morgan: discovered sex linkage in Drosophila, and in subsequent years established the gene theory.
1913 - A.H. Strutevant: built up the first chromosome map (in Drosophila) in which the relative positions of the genes on the chromosomes was indicated.
1914 - G. H. Shull: proposed the concept of heterosis, according to which hybrids between two races how greater vitality and vigour than their parents.
1916 - G. B. Bridges: discovered nondisjunction in the choromosomes of Drosaphila, in which both chromosomes of a pair sometimes pass to the same cell during meiosis.
1916 - H. Winkler: discovered the concept of heteropliody, in which deviation from the normal chromosome number take place.
1922 - C.B. Bridges: proposed the balance theory of sex, according to which sex (in Drosophilla) is determined as a result of a balance between the autosomes and the X heterosomes.
1924 - G.D. Karpechenko: experimentally developed a new species (Raphanobrassica) with 18 chromosomes by crossing the radish (Raphanis : 9 haploid chromosomes) with the cabbage (Brassica: 9 haploid chromosomes).
1927 - H.J.Muller: artifically induced mutation by subjecting Drosophila to X-ray irradiation, and thus laid the foundation for the study of mutations.
1928 - F.Griffith: discovered genetic transduction in bacteria.
1931 - C.Stern, H. Creighion and B.McClintock: cytologically demonstrated crossing over.
1937 - A.F. Blakeslee: artifically produced polyploidy by blocking cell division with the drug colchicines.
1941 - G. W.Beadle and E.L.Tatum: induced biochemical mutation in the bread mould Neurospora by X-ray irradiation.
1943 - T.M.Sonneborn: discovered cytoplasmic or extranuclear inheritance in Paramecium.
1944 - O.T.Avery, C.M. MacLeod and M.McCarly: discovered transformation in bacteria.
1949 - M.L. Barr and E.C. Bertram: discovered sex chromatin (Barrbody).
1950 – E. Chargaff: discovered that DNA the amount of purines is equal to the amount of pyrimidines.
1953 – J.D. Watson and F. C. Crick: elucidated the chemical structure of DNA, a breakthrough in molecular biology.
1956 - J.H. Tjio and A. Levan: give the first correct human chromosome count (46 chromosomes in the diploid condition).
1958 – F. H. C. Crick: proposed the central dogma of molecular biology that DNA determines the sequence of amino acids in a polypeptide.
1959 - C.E.Ford, P.A. Jacob and J.H. Tjio: discovered the chromosomal basis of certain genetic abnormalities
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