Women in Science

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Women in Science

• Part One Biology
• By Helen M. Morgenstern

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Rosalind Franklin

• Born 25 July 1920 -Died 16 April 1958
• English biophysicist and x-ray crystallographer
• She used X-ray diffraction - a technique in which
  a beam of parallel X rays is aimed at molecules -
  to view DNA
• James Watson and Francis Crick used Franklins
  data to build three-dimensional models of the
  structure of DNA, quite possibly without her
  knowledge and/or permission
• She is less known for her work with TMV (tobacco
  mosaic virus)
• After leaving Kings College, she moved to
  Birkbeck College, where she and her team
  completed a model of TMV
• Later, she and Don Casper produced papers that
  demonstrated that the RNA in TMV is wound along
  the inner surface of the hollow virus

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• Using information obtained from her photographs,
  she determined that DNA is a helical structure
  (indicated by the dark areas forming an X) with
  two distinctive regularities of 0.34 nm and 3.4
  nm along the axis of the molecule (indicated by
  the dark crescents at the top and bottom)

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Barbara McClintock

• Born 16 June 1902, Died 2 September 1992
• Studied chromosomes and how they change during
  reproduction in maize
• Used microscopic analysis to demonstrate many
  fundamental genetic ideas such as genetic
  recombination by chromosomal crossover during
  meiosis
• Produced the first genetic map for maize
• Demonstrated the role of the telomere and
  centromere
• Awarded the Nobel Prize in Physiology or Medicine
  in 1983

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Evelyn Witkin

• Born 9 March 1921
• Through her early career she chose to study DNA
  mutagenesis and to work with bacteria
• Her work on mutagenesis led her to work on DNA
  repair
• By characterizing the phenotypes of mutagenised
  E.coli, she detailed the SOS response to UV
  radiation in bacteria, and continued to work on
  the mechanism of the SOS response until her
  retirement.
• SOS response-
• allows the cell to survive otherwise lethal
  events at the expense of generating new mutations
• Happens when a specific base pairing cannot occur
  because of damage
• Involves LexA and RecA genes

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Nettie Stevens

• Born 7 July 1861, Died 4 May 1912
• She was, with Edmund Beecher Wilson, the first
  researcher to describe the chromosomal basis of
  sex
• She was one of the first American women to be
  recognized for her contribution to science
• In research done at Bryn Mawr College, she
  discovered that in some species chromosomes are
  different among the sexesit was the first time
  observable differences of chromosomes could be
  linked to observable differences in physical
  attributes (1905)
• She used the mealworm and fruit flies in her
  experiments
• Finally, she deduced the chromosomal basis of sex
  depended in the presence or absence of the Y
  chromosome.

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Barbara J. Meyer

• Studied at Stanford, UC Berkeley, Harvard
  University, and Cambridge University
• In 1979, worked on gene regulation in lambda
  phage
• Switched from bacteria to C.elegans, because at
  that time the roundworm had not been as widely
  studied, and while studying sex determination,
  discovered the master gene involved
• Is now a professor at UC Berkeley, fully tenured

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Barbara A. Schaal

• Born 1947 in Berlin, Germany
• Best known for her work on the genetics of plant
  species, especially for her studies that use
  molecular genetic data to understand evolutionary
  processes such as gene flow, geographical
  differentiation, and the domestication of crop
  species
• Gene flow - the movement of genes that takes
  place when organisms migrate and then reproduce,
  contributing their genes to the gene pool of the
  recipient population.

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• At Pomona College in California, a professor put
  this question to the students
• Martha Chase, Daisy Roulland-Dussoix , and
  Esther Lederberg are women who participated in
  important discoveries in science. Martha Chase
  showed that phage genetic material is DNA not
  protein, Daisy Dussoix discovered restriction
  enzymes, and Esther Lederberg invented replica
  plating, yet each of these discoveries is often
  credited to the male member of the team (Al
  Hershey, Werner Arber, and Joshua Lederberg,
  respectively). Using the resources of the library
  (at least 5 sources), write a 5 page paper that
  examines how history of science has treated each
  discovery (generally by Hershey, Arber, and Josh
  Lederberg) and include your own appraisal of how
  you might have reacted to the reward structure in
  each case. (This one is a challenge! Feel free
  to reflect in your paper on why it might be so
  hard to find relevant information).

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Martha Chase

• Born 1927 - Died August 8, 2003
• Was part of the Hershey-Chase Bacteriophage
  Experiments of the 1950s that proved that DNA,
  not protein, was the genetic material using the
  bacteriophage T2
• Bacteriophage - a virus that attacks bacteria
• Alfred Hershey won the 1969 Nobel Prize in
  Physiology or Medicine for his discoveries
  concerning the genetic structure of viruses

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Daisy Dussoix

• In 1962, Daisy Dussoix and Werner Arber
  discovered the phenomenon of restriction and
  modification in bacteria aka restriction enzymes
• He did say in his autobiography
• This phenomenon became the topic of Daisy
  Dussoix's doctoral thesis, who very carefully not
  only studied the DNA degradation of phage that
  was not properly modified, but who also tried to
  detect parallels between the fate of unmodified
  DNA in restrictive conditions and of irradiated
  DNA in normal host cells.
• Werner Arber won the Nobel Prize in Physiology or
  Medicine in 1978, not acknowledging Ms. Dussoix

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Esther Lederberg

• Born December 18, 1922-Died November 11, 2006
• Was the first to isolate lambda bacteriophage
  from E. coli (1950), which led to an
  understanding of transduction as the two are
  intimately connected.
• Invented the technique of replica plating,
  originally using velveteenit was very
  innovative.
• Her husband, Joshua Lederberg, did not
  acknowledge her at all in his Nobel Prize
  acceptance speech in 1958 for work that they both
  had done and which she had played a major part.

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Bacteriophage lambda (?)

• ? is a temperate phage, meaning that after
  infecting a bacterial host, it may go through
  either the lytic or lysogenic cycle
• Transduction is DNA transferred from donor cell
  to recipient by transducing phages.
• Replica plating is a technique in which one or
  more secondary Petri plates containing different
  solid (agar-based) selective growth media
  (lacking nutrients or containing chemical growth
  inhibitors such as antibiotics) are inoculated
  with the same colonies of microorganisms from a
  primary plate (or master dish), reproducing the
  original spatial pattern of colonies.