Genetics timeline

Gregor Mendel

Apr 5, 1866

EXPERIMENT
-Mendel's experiment was to test cross pea plants. He self pollinated the pea plants in the first generation, called the P stage, and cross pollinated the pea plants in the next generation, the F1 stage.
CONTRIBUTION
-Mendel's contributions were the laws of segregation, the principle of Independent assortment, that sperm has one allele, and also dominant and recessive traits.

William Bateson and Reginald Punnet

Apr 6, 1908

EXPERIMENT
-Bateson and Punnet worked with two traits in sweet peas. They worked with flower color and pollen shape. They crossed double heterozygous plants (PpLl), and observed the traits they found.
CONTRIBUTION
-They discovered linked genes and punnet squares.

Thomas Hunt Morgan

Apr 7, 1915

EXPERIMENT
-Morgan cross breaded fruit flies with red eyes and white eyes after he noticed the unusual white-eye trait.
CONTRIBUTION
-Morgan discovered sex linked traits, gene mapping, and recombinant frequency.

Archibald Garrod

Apr 8, 1925

EXPERIMENT
-Garrod observed how inherited disease reflects a person's inability to make a particular enzyme, such as the condition alkaptonuria.
CONTRIBUTION
-Garrod discovered the relationship betwene genes and proteins and how genes dictate phenotypes through enzymes.

Frederick Griffith

Apr 9, 1928

EXPERIMENT
-Griffith tested bacteria on mice to see why a single strand of a disease can kill.
CONTRIBUTION
-He discovered information that lead to the discovery of transformation.

George Beadle and Edward Tatum

Apr 10, 1941

EXPERIMENT
-Beadle and Tatum studied strands of the orange bread mold Neurospora crassa that couldn't grow on the usual simple growth medium.
CONTRIBUTION
-These two scientists discovered that the function of an individual gene is to dictate the production of a specific enzyme.

Erwin Chargaff

Apr 11, 1949

EXPERIMENT
-Erwin Chargaff split cells to get a better look at DNA.
CONTRIBUTION
-Chargaff discovered that the amount of Adenine in DNA is equal to the amount of Thymine and that the amount of Cytosine is equal to the amount of Guanine. His conclusion was the base pairing rules

Alfred Hershey and Martha Chase

Apr 12, 1952

EXPERIMENT
-Hershey and Chase used a bacteriophage composed of only DNA and proteins. They tagged the DNA with radioactive phosphorus and the proteins with radioactive sulfur. They then attached to bacteriophage to cells, and split the cells to see where the radioactive material went.
CONTRIBUTION
-They discovered that DNA was the genetic material.

Maurice Wilkins and Rosalind Franklin

Apr 13, 1952

EXPERIMENT
- Wilkins and Franklin took an x-ray of crystallographic photographs of DNA. The work was extremely dangerous.
CONTRIBUTION
-Wilkins and Franklin discovered that DNA is a helix. Their picture also lead to the discovery of the make-up of DNA.

James Watson and Francis Crick

Apr 14, 1953

EXPERIMENT
-Watson and Crick created large wire models of what DNA should look like.
CONTRIBUTION
-Watson and Crick determined that DNA is a double helix and the exact size of DNA.

Marshall Nirenberg

Apr 15, 1961

EXPERIMENT
-Nirenberg synthesized an artificial RNA molecule by linking together identical RNA nuceotides with a Uracil base.
CONTRIBUTION
-Marshall Nirenberg cracked the first codon in the genetic "Rosetta Stone," and it lead to many other discoveries.