BIOL 1105 Lecture Notes - Lecture 17: Sister Chromatids, Down Syndrome, X-Inactivation
13 Nov 2017
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Carol correns: first suggested role for chromosomes in heredity. Walter sutton: observed similar chromosomes paired during meiosis, proposed chromosomal theory of inheritance: chromosomes are the carries of genetic information and the basis for genetic inheritance. Morgan: provided first evidence that genes resided on chromosomes (using eye- color in fruit flies) Morgan conducted genetic studies of the fruit fly and: discovered a mutant male fly with white eyes instead of red, crossed the mutant male to a normal red-eyed female. Results were that all f1 progeny had red eyes, so it was the dominant trait. His experiment proved some of the first ideas of sex chromosomes. Human sex determination: 22 pairs of autosomes, 1 pair of sex chromosomes, y chromosomes highly condensed. Recessive alleles on male"s x have no active counterpart on y: default for humans is female. Requires sry gene on y for maleness
