This site is 100% ad supported. Please add an exception to adblock for this site.

DNA Scientists


undefined, object
copy deck
Friedrich Miescher
1869 (Spain)
~finds a sticky substance inside nucleus which he calls nuclein
Frederick Griffith
~Deadly smooth vs. live rough pneumonia cells in mice...leads to the "Transforming Principle"
Avery and McLeod
~Isolate DNA in the S strain as the substance responsible for transformation (in a test tube)
Hershey/ Chase
~Perform experiment to eliminate the possibility of protein being the genetic material, using bacteriophages and radioactive tags of phosphorus and sulfur
Erwin Chargaff
~Tetranucleotide hypothesis had said that DNA was composed of repeating units; each having 4 nucleotides, complete with ATCG equally. Chargaff discovers...
1) % of ea. nitrogen base varies between species
2) Within a species, % are constant and there are 50% purines to 50% pyridimines.
Wilkins and Franklin
~use x-ray crystallography to determine that DNA is helical in shape
Watson and Crick
~discover DNA to be a double helix with sugar and phosphates making up the sides of the ladder and nitrogen bases joined by hydrogen bonds as the rungs
~complementary base pairing of purine with pyrimidine leads to correct width matching Franklin's x-ray
~paired bases can occur in any order
Meselson and Stahl
~prove DNA replication to be semi-conservative meaning that each side of the old DNA becomes a template for new DNA. Therefore, in every new DNA strand, 1/2 of old exists.
~Synthesis occurs from 5' to 3' end at a rate of 500-5000 bases/minute. Synthesis occurs continuously on the leading strand. Discontinuously on the lagging strand.
~DNA polymerase begins process and checks for errors. (1/100,000 is rate of mutation). DNA ligase joins 3' to 5' pieces.
Rich and Wang
~Discover Z-DNA (left handed spiral). Functions as regulator, possibly.
Sir Archibald Garron
Early 1900s
~Said that there was a relationship between inheritance and enzyme-related disease. ex. diabetes/ insulin, hemophilia/blood-clotting factor: must be link between genes and proteins)
Beadle and Tatum
~Experiment with bread mold (neurospora). Normally, the mold is capable of making all of the enzymes it needs for growth. Beadle and Tatum x-ray the spores to cause mutations in the genes and found that each mutant strain lacked one enzyme. Therefore, they conclude that each gene makes one enzyme.
Linus Pauling/ Itano
~Tests w/ normal and sickle cell hemoglobin (made up of polypeptides) revealed that one mutation leads to structural changes in protein.
Vernon Ingram
~One gene makes one polypeptide...a mutation leads to a defective polypeptide.
Nirenberg/ Matthei
~Crack the genetic code.
~Each 3 nitrogen bases=codon
~Each codon codes for an aminmo acid.
~Only one "start" AUG codon; 3 "stop" codons UAG, UGA, UAA
~101 other codons which code for 70 amino acids

Deck Info