German abbot Gregor Mendel published his famous pea results in 1866, to what can
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Question
German abbot Gregor Mendel published his famous pea results in 1866, to what can be described as a general shrug. Fast forward 35 year when two scientists, Hugo de Vries and Carl Correns, independently arrived to the same conclusions and rediscovered his work. This would catch the general attention and eventually redefined the fields of genetics, evolutionary biology, and population genetics.
In 1904, William Bateson, Edith Saunders, and Reginald Punnett (of the Punnett square fame) published odd results: when selfing pea plants investigating pollen shape and flower color, the F2 generation deviated dramatically from the Mendelian 9:3:3:1 ratio expected of the F2 generation looking at 2 traits:
Discuss how and why those numbers deviate from Mendelian expectations (i.e is there any pattern of divergence in the data ?; what might be causing this divergence?) Why are these surprising or not surprising? Note that purple flowers and long pollen are the dominant phenotypes, while red flowers and round pollen are recessive.
Phenotype Observed Expected Purple, long 1528 1199 Purple, round 106 400 Red, long 117 400 Red, round 381 133 Total 2132 2132Explanation / Answer
Yes. There is a stark divergence on the observed resulted from the expected Mendelian numbers. This is so because the 2 genes (one for flower colour while the other for pollen length) are located close to it other cytologically. As a result of which they are unable to sort independently. The closer 2 genes are on a chromosome the higher us the linkage, lower is the recombination between them and hence they tend to assort together more often. These results are not surprising because for Mendel all his traits assorted independently because he was smart enough to choose those combinations of traits for a given experiment which were present on separate linkage groups i.e on separate chromosomes while the 2 trusts selected by Baetson, Saunders and Punnette were present the same chromosome.
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