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Gregor Mendel
He discovered the fundamental laws of inheritance:
1) The Law of Segregation: Each inherited trait is defined by a gene pair.
2) The Law of Independent Assortment: Genes for different traits are sorted separately from one another so that the inheritance of one trait is not dependent on the inheritance of another.
3) The Law of Dominance: An organism with alternate forms of a gene will express the form that is dominant.
(http://www.dnaftb.org/1/bio.html) -
Friedrich Miescher
"Friedrich Miescher isolated "nuclein," DNA with associated proteins, from cell nuclei. He was the first to identify DNA as a distinct molecule." (http://www.dnaftb.org/15/bio.html) -
Thomas Hunt Morgan
"He started his study in 1910 and 17 years later Morgan and his students (Alfred Sturtevant, Calvin Bridges, Hermann Muller, and others), developed the ideas, and provided the proof for the chromosomal theory of heredity, genetic linkage, chromosomal crossing over and non-disjunction."
(http://www.dnaftb.org/10/bio.html) -
Fred Griffith
"Griffith's famous 1928 experiment with mice and strain bacterias showed us that bacteria can distinctly change their function and form through transformation. Frederick Griffith had identified the S (smooth) strain, has a polysaccharide coat and produces smooth, shiny colonies on a lab plate; the other, the R (rough) strain, lacks the coat and produces colonies that look rough and irregular." (https://www.ck12.org/book/ck-12-biology-concepts/section/4.2/) -
Oswald Avery Colin MacLeod and Maclyn McCarty
"Oswald Avery, Colin MacLeod, and Maclyn McCarty showed that DNA (not proteins) can transform the properties of cells, clarifying the chemical nature of genes. In a very simple experiment, they showed that DNA was the "transforming principle" When isolated from one strain of bacteria, DNA was able to transform another strain and confer characteristics onto that second strain. DNA was carrying hereditary information."
(https://dnalc.cshl.edu/view/15674-Oswald-Avery-c-1930-.html) -
Erwin Chargaff
"Chargaff analyzed the DNA of different species, determining its composition of A, T, C, and G bases. He also made other key observations: A, T, C, and G were not found in equal quantities; The amounts of the bases varied among species, but not between individuals of the same species; The amount of A always equaled the amount of T, and the amount of C always equaled the amount of G (A = T and G = C)."
(Source: Khan Academy) -
Alfred Hershey and Martha Chase
"Alfred and Martha did the Hershey-Chase blender experiment that proved that phage DNA, and not protein, was the genetic material."
(http://www.dnaftb.org/18/bio-2.html) -
Linus Pauling
Linus Pauling suggested a DNA triple helix model, where the phosphates formed the helical core with the bases pointing outwards. Therefore that would be impossible under normal cellular conditions as each phosphate group is negatively charged and so many negative charges forced together would repel each other"
(https://dnalc.cshl.edu/view/15512-linus-pauling-s-triple-dna-helix-model-3d-animation-with-basic-narration.html) -
James Watson and Francis Crick
"They determined that the structure of DNA was a double-helix polymer, or a spiral of two DNA strands, each containing a long chain of monomer nucleotides, wound around each other. According to their findings, DNA replicated itself by separating into individual strands, each of which became the template for a new double helix"
(https://www.history.com/this-day-in-history/watson-and-crick-discover-chemical-structure-of-dna) -
Maurice Wilkins
"Wilkins studied biological molecules like DNA and viruses using a variety of microscopes and spectrophotometers. He eventually began using X-rays to produce diffraction images of DNA molecules. The X-ray diffraction images produced by him, Rosalind Franklin, and Raymond Gosling led to the deduction by James Watson and Francis Crick of the 3-dimensional helical nature of DNA."
(http://www.dnaftb.org/19/bio-4.html) -
Rosalind Franklin
"Franklin solved the DNA structure. Franklin was able to get two sets of high-resolution photos of crystallized DNA fibers. She used two different fibers of DNA, one more highly hydrated than the other. From this she deduced the basic dimensions of DNA strands, and that the phosphates were on the outside of what was probably a helical structure."
(http://www.dnaftb.org/19/bio-3.html)
