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Gregor mendel's work on peas and theories on genes
Gregor Mendel experimented the effect of combinging different charactereistics of pea plants to see what the offspring would look like. This resulted in him making a theorie dominate and recessive traits. -
Period: to
heredity information gathered
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mitosis is described for the first time
Walter Flemming what the chromosone is doing during a cell division. -
DNA is isolated
Frederick Miescher isolates DNA from cells for the first timeand calls it “nuclein”. -
Mendels work is rediscovered
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Nettie Stevens Edmund Wilson described the behavior of sex chromosomes
Independently described the behavior of sex chromosomes-XX determines female; XY determines male. -
the word gene is first used
Wilhelm Johannsen coins the word “gene” to describe the Mendelian unit of heredity. He also uses the terms genotype and phenotype to differentiate between the genetic traits of an individual and its outward appearance. -
The discovery that Chromosones carry genes
Thomas Hunt Morgan studied fruit flies adn their chromosomes with his students. They also discovered genetic linkage. -
Discovery of the structure of DNA
James D. Watson and Francis H.C. Crick discovered that DNA formed a double helix. They created a mpdel to explain their discovery. They later recieved a noble peace prize for this. -
Discovery that a human has 46 chromosomes
Joe Hin Tjio defined the number 46 as the exact number of chromosomes in a human body. -
semiconservative replication od DNA is discovered
Matthew Meselson and Franklin Stahl demonstrate that DNA replicates semiconservatively: each strand from the parent DNA molecule ends up paired with a new strand from the daughter generation. -
The gnetic code is understood
Marshall Nirenberg and others figure out the genetic codethat allows nucleic acids with their 4 letter alphabet to determine the order of 20 kinds of amino acids in proteins. -
the first animal gene was cloned
Researchers fuse a segment of DNA containing a gene from the African clawed frog Xenopus with DNA from the bacterium E. coli and placed the resulting DNA back into an E. coli cell. There, the frog DNA was copied and the gene it
contained directed the production of a specific frog protein. -
PCR is invented
The polymerase chain reaction, or PCR, is used to amplify DNA. This method allows researchers to quickly make billions of copies of a specific segment of DNA, enabling them to study it more easily -
first human genetic map
A map of genes that helps locate diseases and fix the mutations in DNA -
First (nonviral) whole genome sequenced (for the bacterium Haemophilus influenzae).
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discovery that genes are made of DNA
Alfred Hershey & Martha Chase show that only the DNA of a virus needs to enter a bacterium to infect it, providing strong support for the idea that genes are made of DNA