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Gregor Mendel
Experiment -
1.Self pollinated purple plants and self pollinated white plants (P generation)
2. cross pollinated the P generation (F1 generation; all purple)
3. self pollinated the F1 generation (F2 generation; 75% purple, 25% white) Contribution - Law of Segregation and Law of Independent Assortment -
William Bateson and Reginald Punnett
Experiment - with pea plants -
1. PpLl X PpLl
2. predicted 9:3:3:1
3. got 3:0:0:1 Contribution - Punnett Square, linked genes -
Thomas Hunt Morgan
Experiment with fruit flies -
1. crossed GgLl X ggll
2. got GgLl, ggll, Ggll, ggLl Contribution - crossing over, sex-linked traits, and the affect chromosomes have on a trait -
Archibald Garrod
Experiment - Studied Alkaptonuria in families and how it was inherited. He realized that it was an autosomal recessive pattern of inheritance, which led to his contributions Contributions - genes dictate phenotypes through enzymes -
Frederick Griffith
Experiment with Rats -
1. injected "s" bacteria into a mouse; died
2. "r" bacteria into a mouse; lived
3. heat-killed "s" into mouse; lived
4. heat-killed "s" and "r" bacteria into mouse; died Contribution - Transformation -
George Beadle and Edward Tatum
Experiment - exposed bread mold to x-rays, which caused mutations. These mutations caused changes in enzymes. This led them to discover the one-gene, one-polypeptide theory Contributions - One gene - One polypeptide theory -
Erwin Chargaff
Experiment - Chargaff collected DNA from organisms and seperated it using paper chromatography and it wa then analyzed. Contributions - Amount of Adenine = amount of thymine, amount of cytosine = amount of guanine, Adenine always pairs with Thymine, Cytosine always pairs -
Rosalind Franklin and Maurice Wilkins
Experiment - took x-ray crystallographic phtographs of DNA Contributions - DNA is a helix -
Alfred Hershey and Martha Chase
Experiment -
1. Mixed radioactive phages with bacteria
2. agitated the phages in a blender to seperate the phages outside the bacteria from the cells and their contents
3. Centrifuged the mixture so bacteria form a pellet at the bottom of the test tube
4. measured the radioactivity in the pellet and the liquid Contribution - Determined that DNA was the genetic material -
James Watson and Francis Crick
Experiment -
used photos from Rosalind Franklin and Maurice Wilkins' experiment and decided that the DNA had a double-helix formation Contributions - DNA was a double helix made of 2 polynucleotide strands; diameter = 2nm and nitrogen bases were .33 nm apart -
Marshall Nirenberg
Experiment - Produced RNA composed of only Uracil, then added it to a substance that contained DNA, RNA, and ribosomes. He then added DNase, which breaks down DNA. He added a radioactive amino acid and discovered the genetic code for phenylalanine is UUU. Contributions - codons and messenger RNA
