Muller Morgan MCB140 01 31 07 1 5 4 3 2 1 MCB140 01 31 07 3 Boveri 1880 nuclear transplantation in sea urchins early development in triploid sea urchins Sutton 1900 chromosome dynamics in grasshoppers and Mendel s laws note strictly speaking Sutton should have looked at chromosome dynamics in the pea Pisum sativum but whatEVERRR Morgan 1910 correlation between the inheritance of white and the sex chromosomes Bridges 1915 the exceptional female nondisjunction and firm evidence for the chromosome theory of inheritance McClintock Stern 1930 creation of novel genotypes by meiosis via homologous recombination correlates with creation of novel karyotypes via crossingover between nonsister homologs Correlation between cytological and genetic phenomena as a discovery tool Sturtevant Bridges The Fly Room Columbia University ca 1919 MCB140 01 31 07 4 Criss cross inheritance white eyed sons and red eyed daughters of whiteeyed mothers and red eyed fathers MCB140 01 31 07 2 1 MCB140 01 31 07 5 G Rubin and E Lewis Science 287 2216 MCB140 01 31 07 7 A Bridges left and Sturtevant in 1920 B Morgan in 1917 The photo of Morgan who was camera shy was taken by Sturtevant using a camera hidden in an incubator and operated remotely by means of a string The books and microscope in the background were at Sturtevant s desk raised by his grandparents in upstate New York both of his parents dying young He was a talented student buit his grandparents were poor and Bridges had to make do with clothing that was constantly mended He was too ashamed to go to social activities in high school because of his ragged appearance He received a scholarship to attend Columbia University but he had to support himself with part time work Bridges took the same introductory biology course as Sturtevant and Morgan who learned of Bridges circumstances asked him to be a part time bottle washer and food preparator for the fly work that was gaining momentum in Morgan s laboratory Carlson Mendel s Legacy Calvin Bridges Everything to do with Fig 5 21 Pp 149 154 of Ch VI in Morgan et al The Mechanism of Mendelian Heredity Problems 4 32 and 4 34 Everything to do with Fig 14 32 Required reading MCB140 01 31 07 8 MCB140 01 31 07 6 Bridges circumstances changed approximately a year after he began working for Morgan He showed Morgan a bottle that contained a fly whose eye color seemed to be brighter than usual Morgan isolated the fly showed that it carried another X linked trait and called that trait vermilion He also assigned Bridges to a desk and told him to look for more mutations vermilion 2 Fig 13 28 The exceptional female appears MCB140 01 31 07 11 MCB140 01 31 07 9 Fig 4 21 MCB140 01 31 07 12 Stay tuned for Prof Cline s lecture Y Note An XXY Drosophila is female An XXY human is male How could a white eyed mother have a white eyed daughter MCB140 01 31 07 10 3 MCB140 01 31 07 14 MCB140 01 31 07 16 MCB140 01 31 07 13 MCB140 01 31 07 15 4 White eyed daughters of an exceptional mother Normal female MCB140 01 31 07 19 MCB140 01 31 07 17 MCB140 01 31 07 20 MCB140 01 31 07 18 5 MCB140 01 31 07 23 MCB140 01 31 07 21 Bridges C B 1935 Salivary chromosome maps with a key to the banding of the chromosomes of Drosophila melanogaster J Hered 26 60 64 2 Highly aberrant phenotypic ratios e g 9 3 4 when for example brother sister mating black Labrador retrievers fathered by a black Dad and yellow Mom epistasis MCB140 01 31 07 24 The next two major advances in genetics both came from the study of apparent exceptions to Mendel s laws 1 Strong deviations from a 1 1 1 1 phenotyping ratio in a AaBb x aabb cross coupling and repulsion linkage genetic map Fine fine genes are on chromosomes Now what MCB140 01 31 07 22 6 http www ndsu edu instruct mcclean plsc431 linkage linkage1 htm MCB140 01 31 07 27 MCB140 01 31 07 25 It was not long from the time that Mendel s work was rediscovered that new anomalous ratio began appearing One such experiment was performed by Bateson and Punnett with sweet peas They performed a typical dihybrid cross between one pure line with purple flowers and long pollen grains and a second pure line with red flowers and round pollen grains Because they knew that purple flowers and long pollen grains were both dominant they expected a typical 9 3 3 1 ratio when the F1 plants were crossed The table shows the ratios that they observed Specifically the two parental classes purple long and red round were overrepresented in the progeny Hmmmmm 21 21 55 381 Purple round P ll Red long ppL Red round ppll Total 381 24 71 71 215 Expected MCB140 01 31 07 26 MCB140 01 31 07 28 1 How do we know there s a problem Is this really a deviation from 9 3 3 1 or should they look at more seeds 2 If there really is a deviation how can one explain it Two separate issues http www ndsu edu instruct mcclean plsc431 linkage linkage1 htm 284 Purple long P L Observed Coupling and repulsion 7 MCB140 01 31 07 31 For the application of existing knowledge the potential effects of genetic inequity are chilling According to GeneTests http www genetests org there are currently 1 054 clinical tests and 297 research tests for 1 351 diseases MCB140 01 31 07 29 Legislation to prevent genetic discrimination in employment and insurance decisions is essential so that individuals can make use of existing genetic tests to manage their own health decisions This legislation is also imperative to protect those who volunteer for genetic research that will benefit others affected by common diseases GINA aGAIN Nature Genetics 39 133 2007 The 2 test of goodness of fit Karl Pearson Tests of significance MCB140 01 31 07 32 MCB140 01 31 07 30 The Genetic Information Nondiscrimination Act GINA legislation to prevent the use of genetic information in employment and insurance decisions has been introduced six times in various forms to the US Congress over the last 12 years and has been unanimously passed twice by the US Senate but not by the House of Representatives Proponents of the Act have a fresh opportunity with the newly elected 110th Congress GINA The legislation is essential if human genetic research is to continue with full public support and deliver the anticipated health benefits that underpin much of its funding Most crucially the human genome belongs to the whole human race leading to the essential principle of genetic solidarity and altruism so aptly described by the UK Human Genetics Commission in their 2002 report on the use of personal genetic data entitled Inside
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