DNA: A historical Perspective

Timeline created by tommbrennan
Event Date: Event Title: Event Description:
Gregor mendel Gregor Mendel publishes "Experiments on Plant Hybridization (Versuche über Pflanzen-Hybriden)" Gregor Mendel, an austrian scientist, discovered the field of genetics through the study of the reproduction of pea plants. In his paper "Experiments on Plant Hybridization" Mendel discuses the inheritance of similar traits (ie. green pod vs yellow pod), and that some traits show dominance over other traits and are more likely to be expressed in the next generation while the less dominant trait was less likely to be expressed. This led to Mendels laws of Genetics.
Fredm Friedrich Meischer discovers nucleic acid Friedrich Meischer, a swiss scientist, born in 1844. discovered nucleic acid. he did this through collecting white blood cells, through the pus on used bandages from infections. he did this by mixing the pus with a sodium sulfate salt solution, which stripped the nuclei from the cytoplasm of the cells then he placed them in an alkaline solution and the percipitate that appeared was DNA
Wsutton Walter Sutton Discovers that chromosomes are responsible for inheritance walter sutton, an american geneticist, born in 1877, found out that the chromosomes in the nucleus were responsible for inheritance and traits. this was discovered by observing grasshopper cells during meiosis. he discovered that the paired up chromosomes split apart during meiosis and formed a new cell that only contained half of the chromosomes which when it combines with the opposite gamete, would begin to reproduce and show the inheritance that Mendel studied.
Thmorgan Thomas Hunt Morgan through his research with the fruit fly, he discovered that, some traits could be associated with sex. such as how when he bred a white eyes male fly with a red eyed female fly all their offspring had red eyes, but as he kept inbreeding the flys the white eyed trait became more prevelant and always remained in the male fruit flys.
Timeline Frederick Griffith's Experiment in this experiment transformation of bacteria was discovered my Frederick Griffith. This was discovered when two strains of bacteria, one being a strain lethal to mice and one being a strand not lethal to mice. Griffith discovered that although the lethal strand, when killed with high heat would not kill the mouce, was mixed with the non lethal strand, that the non lethal strand would take upon the traits of the lethal strand and become lethal to the mouse.
Beadtatum Beadle and Tatum discover that each gene controls one enzyme this was proved when they bombarded Neurospora crassa, a bread mold with exrays, they then put the samples in agar, a minimal growth medium, they also put non-mutated Neurospora crassa into agar aswell. in the non mutated culture the Neurospora created all essential moleucles, while the mutated Neurospora could not and died. then when they placed the mutated Neurospora in a Complete Growth Medium which had all 20 amino acids, it would continue to grow. proving that one gene controls one enzyme.
Chargaffbaby Erwin Chargaff's doscovery and Chargaff's Rules chargaff discovered that different species DNA contained different ratios of nucleotides (ie. humans had 30.3% adenine compared to E.coli having 26.0% adenine). he also discovered that the ratios between adenine and thymine, and cytocine and guanine, in one species DNA are almost always near equal. this led to Chargaff's Rules. #1. the base composition varies between species. #2 within a species, the number of A and T bases are equal and the number of G and C bases are equal.
Handc Hershey–Chase experiment two scientists Alfred Hershey and Martha Chase, confirmed in 1952 that DNA is infact the material responsible for genetics and inheritance. this was done using the T2 phage, a virus, and bacteria. using radioactive phosphorus to lable the DNA of the T2 phage and radioactive sulfur to lable the protein shell of the T2 Phage. with this they saw that the DNA of the T2 Phage went in and forced the cell to produce more T2 phages by infecting the DNA of the cell
Dnastructure Watson and Crick discover the structure of DNA the discovery of the structure of DNA happened when scientists James Watson and Francis Crick used disfracted X-rays to view DNA's structure of a double helix. they also discovered the pairings of thymine with adenine and, guanine wity cytocine.
Timeline Barbara McClintock discovers jumping genes Barbara Mc Clintock discovers that genes have the ability to move from one site on the DNA molecule to another. these genes were called jumping genes and could do this through a recombination process with the proteins. this was found when she did breding experiments with corn throughout the 1940s and the 1950s. she tracked the changes in the corn through multiple generations
Semiconmod Meselson and Stahl publish "THE REPLICATION OF DNA IN ESCHERICHIA COLI" in the experiment, Meselson and Sthal were trying to determine which model of DNA replication was correct. their options were the conservative model, The Semi conservative model, and the Dispersive model, in which each molecules conatined a mixture of parent and daughter strands. they solved this by taking bacteria with DNA with a heavy Nitrogen isotope and putting it ina solution with ligher isotope of Nitrogen. the semiconservative model was found to be correct. see picture and link
Timeline Monod and Jacob discover that ribosomes can manufacture any protein in 1961 Francois Jacob and Jacques Monod discovered that with the use of a short lived RNA molecule, that the ribosome could produce any protein needed for the cell.
Timeline Nirenberg and Leder experiment in 1961 Marshall Nirenberg and Philip Leder, were able to crack the genetic code of RNA and protein production. there were able to discover that in each mRNA molecule is seperated in to sections of 3 nucleotides which are responsible for which protein that gets synthisized in the ribosomes.
Timeline The first Genetically engineered organism is made the first genetically engineered organism was made in 1972 by Paul Burg using DNA from the Lambda virus and the Monkey virus SV40, using these two DNA samples he made recombinant DNA then put it in the plasmid of an E.Coli cell
Timeline Discovery of telomeres and Telomerase Telomerase and telomers were discovered by Carol Greider and Elizabeth Blackburn in 1984. telomers are a sequence of nucleotides at the end of DNA molecues. they do not contain genes, but repeate a nucleotide sequence. telomerase extendes these telomers to protect the cell from any damage or the activation of cells system for monitering and correcting DNA damage.
Timeline embryonic stem cells and their research embpyonic stem cells are the cells of an embryo. these cells have are importand due to the fact that they are cells with out a specific function set for them, and can when other cells are introduced become like thoes cells. although it has much potential to help cure damage to nervs amongst other possibilities for the stem cells, research on them are contriversial due to the fact that they must be taken from an embryo.
Glofish First genetically engeneered pets GloFish! in 2003 tiwan approved the first Genetically engineered pet for sale. it was titled Glowfish and it was ordinary zebra fish that were genetically altered to be florescent neon colors.
Tinyminy Ageing gene in mice identified japanese scientists discovered the gene and were able to repress and alter it. this caused the mice that were affected to age slowly. although these mice display tissue athrophy amongst other issues.
Timespan Dates: Timespan Title: Timespan Description:

The Human genome project the human genome project is an attempt to map the entire human genome and sequence of neucleotides. it was essentially completed in 2003 but continued to be refined untill 2006 when the last chromosome was mapped out fully