Download IB Biology / Year 2 Approx. Two Dozen Scientists Named in IB Bio

IB Biology / Year 2
Approx. Two Dozen Scientists Named in IB Bio Curriculum (First Exams 2016)
Scientist
Cairns, John
Calvin, Melvin
Darwin, Charles
Davson-Danielli
Florey-Chain
Franklin, Rosalind
Harvey, William
Hershey-Chase
experiment
Jenner, Edward
Linneaus, Carolus
Lorenz, Konrad
Mendel, Gregor
Meselson-Stahl
Mitchell, Peter
Morgan, Thomas
Hunt
Pasteur, Louis
Pavlov, Ivan
Singer-Nicholson
Skinner, B.F.
Watson, James and
Francis Crick
Woese, Carl
Contribution
Estimated the length of a DNA molecule with autoradiography by growing E. coli in a
medium with radioactive thymine, breaking the cells open, and applying the cell
contents to film. Radiation emitted from the *T develops (darkens) the film.
Elucidated the pathways of C-fixation with his famous "lollipop experiment," which
required C-14 and autoradiography.
Developed the theory of evolution by natural selection.
Envisioned a model of the cell membrane as a lipid layer-protein interior-lipid layer
sandwich. But the Singer-Nicholson model (fluid mosaic model) fit the evidence much
better!
Tested penicillin on mice challenged with dangerous streptococci; mice that got pen.
recovered, while those that did not died of infection. Then they tried pen. six people,
including a woman with incurable cancer (to see if it was toxic) and a policeman with a
terrible infection. The policeman's condition at first improved but then F-C ran out of
pen. and the policeman relapsed and died of his infection.
Her X-ray diffraction photographs of DNA provided crucial evidence that DNA is a
double helix. Did not receive Nobel prize because she died of cancer prior to the award.
Overturned ancient Greek theories on the movement of blood in the body, and on
sexual reproduction/embryonic development in deer.
Provided evidence that DNA, not protein, is the genetic material. Experiment involved
deliberately infecting E. coli with bacteriophages that consisted of radioactively-labeled
protein or radioactively-labeled DNA. Only when the DNA was labeled did the
"offspring" phages contain radioactivity.
Tested his vaccine for smallpox, which was to deliberately infect the patient with a
weak, similar virus called cowpox, on the son of his gardener!
Pushed for the adoption of a system of binomial nomenclature for identifying a species
(instead of using one of several local names).
Imprinting is learning occurring at a particular life stage and that is independent of the
consequences of behavior. Baby geese imprint on the first big thing they see that
moves, which is usually their mother, but in the case of Lorenz, him!
Discovered principles of inheritance with systematic crosses of pea plants. Came up
with the laws of Segregation ("factors" for a gene are separated/segregated at meiosis
and come back together at fertilization) and of Independent Assortment.
Obtained evidence for the semi-conservative replication of DNA by providing bacteria
with different N isotopes (like N-14 and N-15) during DNA replication and separating
the different double helix "offspring" by mass (centrifugation).
Chemiosmotic theory - the flow of H+ ions down their gradient and across ATP
synthase, resulting in the phosphorylation of ADP to form ATP. Chemiosmosis is how
the ETC and its associated H+ gradient are coupled to ATP synthesis.
Fruit fly geneticist at Columbia, first to propose that the white eye trait in Drosophila is
"sex linked" (that is, that the gene for white eyes was on the X chromosome).
French scientist whose experiments with sterile broth and flasks with long, curved
necks provide evidence that spontaneous generation of cells does not today occur on
Earth.
Did classical conditioning with dogs (IB calls 'reflex conditioning') – dogs learned to
salivate at the sound of a bell.
Fluid mosaic model for cell membrane. Double layer of lipids in which proteins "float"
Did operant conditioning – trial and error learning, like the way a rat in a box learns
that pressing a lever results in the delivery of food pellets to the box.
With M. Wilkins, received Nobel Prize for working out the structure of DNA as a double
helix by building models and integrating others' observations.
First recognized that Archaea have a separate line of evolutionary descent from
Bacteria. Archaea, Bacteria, and Eukarya are the three domains of life.
IB Biology / Year 2