Microbiology Scientists

Front 1

First postulated that genes are on chromosomes and that many genes are one each chromosome.

Merged the fields of genetics and cytology.

Back 1

Walter S. Sutton

Front 2

First to explain the rule of sex-linked inheritance.
Worked with Drosophila.

Reasoned that genes located close together on a chromosome would assort with one another more regularly than those far apart.

Back 2

Thomas Hunt Morgan

Front 3

First described the cytological basis of crossing over, also known as recombination.

Did not formally prove what happened.

Back 3

F.A. Janssens

Front 4

Found actual rpoof of Janssen's hypothesis that chromosomes physically interchange material during synapsis.

Did so by observing extra "chunks" of chromosomes moving.

Back 4

McClintock and Creighton

Front 5

Discovered that yeast was the agent responsible for fermentation.

Back 5

Louis Pasteur

Front 6

Worked with C. elegans.

Studied organ development and programmed cell death.

Back 6

Sydney Brenner

Front 7

Studied "nutritional mutants" of Neurospora. Built support for "one gene one enzyme" hypothesis.

Back 7

Beadle and Tatum

Front 8

Worked with S and R strains of Streptococcus pneumoniae. Heat-killed S (smooth, pathogenic) strain, injected with live R bacteria, and found that the live R strain would be transformed into the pathogenic S strain and kill the mice.

Back 8

Frederick Griffith

Front 9

Modified Griffith's experiment to conclude that DNA encoded hereditary material and was the "transforming agent." Isolated S strain DNA.

Back 9

Oswald T. Avery

Front 10

Used radioactive sulfur and phosphate to "follow the molecules" working with S and P strains. Confirmed that DNA is the genetic material.

Back 10

Martha Chase and Alfred Hershey

Front 11

Used x-ray crystallography to obtain diffraction pictures of DNA.

Back 11

Franklin and Wilkins

Front 12

Used Franklin and Wilkins' x-ray diffraction pattern to determine the structure of DNA.

Back 12

Watson and Crick

Front 13

Measured the amount of each nucleotide within cells from various organisms.

Found that the ratio of A:T ~ 1 and C:G ~ 1.

Back 13

Erwin Chargaff

Front 14

Found that cell-free extracts (cytoplasm) from bacteria could synthesize DNA.

Showed that an enzyme was needed to catalyze the polymerization of nucleotides into DNA: DNA polymerase 1.

Back 14

Arthur Kornberg

Front 15

Used different radioactive isotopes of nitrogen that were incorporated into daughter strands of DNA.

Determined that DNA replication is semiconservative

Back 15

Meselson and Stahl

Front 16

Pea plants, genetics, independent assortment, independent segregation.

Back 16

Mendel