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Gregor Mendel
Gregor Mendel, through his work on pea plants, discovered the fundamental laws of inheritance.
Mendel showed that the inheritance of these traits follows particular laws, which were later named after him. The significance of Mendel's work was not recognized until the turn of the 20th century. The independent rediscovery of these laws formed the foundation of the modern science of genetics. -
Hugo de Vries
He was a Professor of Botany at the University of Amsterdam when he began his genetic experiments with plants in 1880. He completed most of his hybridization experiments without knowing about Mendel's work. Based on his own results, de Vries drew the same conclusions as Mendel. De Vries published his work in 1900.
De Vries believed species evolve from other species through sudden, large changes of character traits. De Vries based this "theory of mutation" -
Friedrich Miescher
He began working on white blood cells and started collecting pus from bandages in the Hospital and then puour them in salty water. then a substance was made he called nuclein.
He isolated the first crude preparation of DNA, he just didn’t know it. He named it nuclein. -
CARL ERICH CORRENS
Correns was a tutor at the University of Tübingen when he began to experiment with trait inheritance in plants in 1892. Correns already knew about some of Mendel's hawkweed plant experiments from Nägeli. Nägeli, however, never talked about Mendel's key pea plant results, so Correns was initially unaware of Mendel's laws of heredity. However, by 1900, when Correns submitted his own results for publication, the paper was called: G. Mendel's Law Concerning the Behavior of the Progeny of Racial Hybr -
ERICH VON TSCHERMAK-SEYSENEGG
In 1898, he started doing plant breeding experiments using peas, and by 1900, he had written up his results. Tschermak, like de Vries and Correns, independently derived "Mendelian" laws of inheritance from his plant experiments. Because he was younger, and not as established in the scientific community, Tschermak was worried about the acceptance of his paper given those of de Vries' and Correns'. -
Thomas Hunt Morgan
Thomas Hunt Morgan established the chromosomal theory of inheritance. As a young boy in Lexington, Kentucky, Morgan loved exploring the countryside collecting samples of wild life and fossils. At the State University of Kentucky, Morgan's course load was heavy in the natural sciences. -
Hermann Müller Thurgau
Hermann Muller showed that X-rays could induce mutations. Born in Manhattan in 1890, he grew into a 5'2" science geek.As a boy, Hermann spent summers hiking in the Adirondack Mountains and spent nights pondering how life would be on the planets he viewed through his telescope.In the 1920s, Muller performed his Nobel prize-winning research showing that X-rays could induce mutations and he became instantly famous. -
BARBARA MCCLINTOCK
Barbara McClintock did pioneer work in plant genetics and determined the mechanism for transposition in corn.
She met fellow graduate students Marcus Rhoades and George Beadle who became lifetime friends as well as colleagues. McClintock helped Beadle sort out the Neurospora chromosomes. Beadle, with Edward Tatum, built on this work and developed the "one gene, one enzyme" theory using Neurospora. -
GEORGE WELLS BEADLE
George Beadle, "Beets" to his friends, and Edward Tatum experimentally demonstrated the “one gene one protein” hypothesis. Born in Wahoo, Nebraska.
While working on his master's degree on the ecology of grasses, Beadle became interested in genetics. He applied to graduate school at Cornell University and, in 1927, joined R. A. Emerson's group to work on corn genetics. -
EDWARD LAWRIE TATUM
Tatum chose intellectual challenge over money. He spent the first few years in Beadle's lab isolating and identifying the "substances" involved in Drosophila eye color determination – an extension of Beadle's earlier work. They were beaten by another group, but this set into motion the events leading up to the Neurospora experiments. The switch to Neurospora supposedly came about after one of the biology classes Tatum volunteered to teach. -
JOSHUA LEDERBERG
At Columbia, Lederberg became interested in Beadle and Tatum's Neurospora experiments, which opened up new and exciting research possibilities especially in the fledgling field of genetic analysis. In 1943, Lederberg got a job as a media-prep gofer in Frances Ryan's lab in the Department of Zoology. Ryan was a post-doc at Stanford in 1941-42, where he met Beadle and Tatum and became interested in using Neurospora as a research model. -
OSWALD THEODORE AVERY
Oswald Avery and Maclyn McCarty showed that Fred Griffith’s “transforming principle" was DNA.
Avery worked on many strains of bacteria, applying different immunological and chemical methods. In 1913, Avery published a clinical study of the tuberculosis bacterium. This work attracted the attention of Dr. Rufus Cole, the director of the Rockefeller Institute Hospital, who offered Avery a job at the Rockefeller. Avery did his Pneumococcus work at the Rockefeller and stayed there until his retireme -
Erwin Chargaff
Chargaff discovered two rules that helped lead to the discovery of the double helix structure of DNA.
Rule1:holds that a double-stranded DNA molecule globally has percentage base pair equality: %A = %T and %G = %C. The rigorous validation of the rule constitutes the basis of Watson-Crick pairs in the DNA double helix.
Rule2:holds that both %A ~ %T and %G ~ %C are valid for each of the two DNA strands.This describes only a global feature of the base composition in a single DNA strand. -
ROSALIND ELSIE FRANKLIN
Rosalind Franklin produced the Xray crystallography pictures of BDNA which Watson and Crick used to determine the structure of double-stranded DNA.
Working with a student, Raymond Gosling, 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. -
FRANCIS HARRY COMPTON CRICK
Besides coming up with the double helix structure for DNA with James Watson, Crick also proposed the Central Dogma and Adaptor Hypothesis.
After the "double helix" model, there were still questions about how DNA directed the synthesis of proteins. Crick and some of his fellow scientists, including James Watson, were members of the informal "RNA tie club," whose purpose was "to solve the riddle of RNA structure, and to understand the way it builds proteins." -
ALFRED DAY HERSHEY
Alfred Hershey and Martha Chase did the Hershey-Chase blender experiment that proved phage DNA, and not protein, was the genetic material.
For this, and his body of work on bacteriophage, Hershey shared the 1969 Nobel Prize for Physiology and Medicine with Max Delbrück and Salvador Luria. -
SEYMOUR BENZER
In 1953, after Watson and Crick published their model of DNA, Benzer hatched his plan to get inside the gene by using bacteriophage with mutant rII genes. Max Delbr¸ck ridiculed the plan and told Benzer "you must have drunk a triple highball before writing this." Benzer's 5-year-old daughter Martha liked the plan better and sketched her vision of two phages infecting a bacterium. In 1971, Benzer received the Lasker Award for this "brilliant contribution to molecular genetics." -
EVELYN WITKIN
She built on her work on DNA response to UV radiation, laying the foundation for the elucidation of the molecular mechanisms by which UV-induced mutagenesis may be repaired. Witkin concentrated on understanding the cellular response to UV throughout her career, moving to Rutgers University in 1971, and remaining there until her retirement in 1991. -
MAHLON HOAGLAND
He then began working on a project that Zamecnik had put on hold. This led to the discovery of tRNA, the adaptor (predicted by Francis Crick) that shuttles amino acids to messenger RNA. The results were published in 1957 and served to connect two fields of science research, biochemistry and molecular biology. -
PAUL CHARLES ZAMECNIK
Paul Zamecnik and Mahlon Hoagland determined the identity of Crick’s adaptor molecule, tRNA.
Zamecnik continued to work on tRNA purification and sequencing. Then in 1978, he made another interesting observation. He found that oligonucleotides were able to enter cells. This led to a new area of research and possible therapy. Anti-sense RNA could be used to block the translation of viral messenger RNA. -
FRANKLIN WILLIAM STAHL
In 1957, Stahl and Meselson developed the technique of density gradient centrifugation and used it to prove that DNA was replicated in a semi-conservative way, as predicted by Watson and Crick in their 1953 paper. Meselson and Stahl's paper appeared in 1958.In 1959, Stahl accepted a position at the University of Oregon where he is now a distinguished professor of Molecular Biology. His current research interest is on the mechanisms of genetic recombination. -
MATTHEW STANLEY MESELSON
Meselson and Stahl experimentally proved Watson and Crick’s model of semi-conservative replication.
1957 the two had the experimental proof for the semi-conservative replication of DNA. They did this by inventing a new technique called density gradient centrifugation, which uses centrifugal force to separate molecules based on their densities. Their "classic" paper was published in 1958 and their experiment has been called "one of the most beautiful experiments in biology." -
LINUS CARL PAULING
was an American chemist, peace activist, author, and educator. He was one of the most influential chemists in history and ranks among the most important scientists of the 20th century.[1][2] Pauling was among the first scientists to work in the fields of quantum chemistry and of molecular biology. -
ARTHUR KORNBERG
In 1953, Kornberg was appointed head of the Department of Microbiology in the Washington University School of Medicine in St. Louis. It was here that he isolated DNA polymerase I and show that life (DNA) can be made in a test tube. In 1959, Kornberg shared the Nobel Prize for Physiology and Medicine with Severo Ochoa—Kornberg for the enzymatic synthesis of DNA, Ochoa for the enzymatic synthesis of RNA. -
MARSHALL WARREN NIRENBERG
They showed that a synthetic messenger RNA made of only uracils can direct protein synthesis. The polyU mRNA resulted in a poly-phenylalanine protein – they had the first piece of the genetic code. In subsequent years, Nirenberg and his group deciphered the entire genetic code by matching amino acids to synthetic triplet nucleotides. They found that there is redundancy in that some codons coded for more than one amino acid and some codons are "punctuation marks" in the mRNA message. -
FRANÇOIS JACOB
n 1961 Jacob and Monod explored the idea that the control of enzyme expression levels in cells is a result of feedback on the transcription of DNA sequences. Their experiments and ideas gave impetus to the emerging field of molecular developmental biology, and of transcriptional regulation in particular. -
JACQUES LUCIEN MONOD
Jacques Monod and François Jacob were the first to discover how genes were turned on and off. -
SYDNEY BRENNER
In 1960, Brenner, FranÁois Jacob, and Matthew Meselson designed and worked on another series of experiments establishing the existence and function of messenger RNA.In the late 60's, Brenner became interested in the problem of development, especially that of the nervous system. In 1968, having decided against Drosophila melanogaster as too complex, Brenner chose Caenorhabditis elegans as a model organism for study. C. elegans is now a research field onto itself. -
ROY JOHN BRITTEN
Roy Britten showed that eukaryotic genomes have many repetitive, noncoding DNA sequences.
DNA sequences.
Since his work on repetitive DNA, Britten has been interested in evolutionary biology, specifically the nature of repetitive DNA and its origin and evolutionary history. He has done work on human repetitive DNA elements like Alu, and repetitive DNA elements in sea urchins -
DAVID BALTIMORE
he began to suspect that not all RNA viruses replicated in the same manner.Baltimore knew about Howard Temin's DNA provirus hypothesis that viral RNA was a template to make viral DNA, which then became the template for the synthesis of progeny viral RNA.
Baltimore thought Temin's theory was logical and was able to prove it by finding the RNA-dependent DNA polymerase. -
HOWARD MARTIN TEMIN
he developed his provirus theory, which hypothesized that RSV and other RNA viruses entered the cell and then made DNA copies of themselves before integrating into the host genome. -
STANLEY NORMAN COHEN
Leslie Shiu, a graduate student in Cohen’s lab, found that adding calcium chloride increases the chances that plasmid DNA would be incorporated by bacteria. Transformed bacteria would then maintain and propagate the plasmid DNA. Cohen saw the implications; this was a natural Xerox machine for DNA. If DNA could be first introduced into plasmids and then transformed into bacteria, then large quantities of DNA could be produced. Cohen worked on ways of breaking up the plasmids. -
HERBERT W. BOYER
At a conference in Hawaii in the early '70s, Boyer met Stanley Cohen who was working on plasmids rings of extra chromosomal DNA. The two began a collaboration that eventually led to the creation of the first recombinant DNA. -
RICHARD JOHN ROBERTS
In 1974, Roberts and Richard Gelinas started working with the adenovirus mRNA. They reasoned they could identify the DNA promoter region by sequencing the 5' end of the mRNA and then mapping it to the DNA. The promoter would be upstream of the 5' end of the mRNA. Through the course of their experiments, they discovered biochemical proof that the genes in adenovirus were split. -
ROGER KORNBERG
Roger Kornberg figured out the importance of histones to chromatin structure.
In 1972, Kornberg went to the Medical Research Council in Cambridge for postdoctoral work in X-ray crystallography. There he became interested in the X-ray patterns Aaron Klug obtained for chromatin. Using this and other experimental data, Kornberg eventually worked out the importance of histones to chromatin structure. Kornberg published his results in 1974. -
FREDERICK SANGER
Solving the problem of DNA sequencing became a natural extension of his work in protein sequencing. Sanger initially investigated ways to sequence RNA because it was smaller. Eventually, this led to techniques that were applicable to DNA and finally to the dideoxy method most commonly used in sequencing reactions today. -
LELAND HARTWELL
he wanted to work on cell division, which was one of Dulbecco's research interests.
He also made the rather risky decision to start using yeast as a model system. Not many people were using yeast at the time, but Hartwell wanted and needed a simpler experimental system to study basic questions of cell growth. Hartwell is a pioneer in yeast genetics, and has used yeast to identify many of the genes involved in protein synthesis as well as the cell cycle. -
ERIC FRANCIS WIESCHAUS
he learned the basics about fruit flies, but he was much more interested in embryology, and questions like: "how do cells know what to do as an embryo develops?", "what drives differentiation and development?"
Wieschaus thought he might not have a chance to find out because just as he was finishing college.
His research continues to focus on development, specifically on changes in cell shape during the various developmental stages. -
KARY MULLIS
he carried out research on the synthesis of oligonucleotides - short DNA sequences of up to twenty nucleotide bases.
Mullis invented the polymerase chain reaction (PCR), a technique that amplifies specific DNA sequences from very small amounts of genetic material.
PCR has revolutionized DNA technology by allowing scientists to produce an almost unlimited amount of highly purified DNA molecules suitable for analysis or manipulation. -
THOMAS ROBERT CECH
he and his research group did the work leading to the discovery that RNA can self-splice and thus can act as a ribozyme. -
MARIO RENATO CAPECCHI
In 1980, Mario Capecchi faced an uncertain future. Reviewers deemed the research proposal he sent to NIH "not worthy of pursuit," so Capecchi gambled and diverted money from other projects into the new research.
he was on his way to harnessing the machinery of mammalian cells to precisely mutate any gene he wished.The technique not only helps researchers generate mice with human diseases for study, but it may be used in future gene therapies to correct disease-causing genes. -
HOWARD ROBERT HORVITZ
Horvitz was interested in neurobiology, but because of his limited experience with biology in general, he started working with phage (a virus that infects bacteria)
Caenorhabitis elegans is a non-parasitic roundworm that is amenable to genetic analysis, and is easy to grow and maintain. Horvitz saw the advantages of C. elegans, and used it to study a number of developmental systems including neuronal development.Programmed cell death is only one of the many ongoing projects in his lab. -
JOHN SULSTON
This millimeter-long worm is particularly advantageous as a model organism as it is transparent and has only 959 cells, so every cell division and differentiation can be followed under the microscope.
Furthermore, he realized that certain cells in the lineage always died at a certain time by what appeared to be a programmed cell death. As part of this work, Sulston demonstrated the first mutation of a gene participating in programmed cell death, the nuc-1 gene.
