BIO152H5 Chapter Notes - Chapter 15: Haplodiploidy, Y Chromosome, Mendelian Inheritance
Document Summary
Chapter 15: chromosomal basis of inheritance. Tuesday, december 9, 2014. >> species of fruit fly: drosophila melanogaster. >> reason: single mating will produce hundreds of offspring, a new generation can be bred every two weeks. They also have only 4 pairs of chromosomes (3 autosomes & one sex) Wild type (w+ ): phenotype most commonly seen in natural population. >> alternative traits are called: mutant phenotypes (w) [assumed to have originated from mutations] In the fruit fly, the mutant phenotype (white eye) only occurred in males. Chromosomal basis of sex. Y is much smaller than x. Short segments at either y chromosome are the only regions that are homologous to regions of x. Chromosomal systems of sex determination. >> x- 0 system (occurs in grasshoppers, cockroaches & some other insects) Females xx, males x0. >> zw system (birds & some fishes , insects and reptiles) females zw males zz.
