BIOL207 Lecture Notes - Lecture 12: Punnett Square, Chromosome, Organelle
Document Summary
Females are either heterozygous or homozygous: heterozygous: same gene different alleles. Males are hemizygous ( hemi- = half: the only have 1 x-chromosome out of the 2 sex chromosomes. The white eye gene in drosophila is x-linked and recessive: heterozygous females will have red eyes. Red eyed females and white eyed males will be the two exhibited phenotypes of the next generation. Here"s the punnet square to show how this comes about: There is an x-linked red gene: o = orange, o = black. Female cats that are heterozygous for this gene will exhibit orange and black spotted coats: homozygous for o" will give them orange coats, homozygous for o" will give then black coats. For males, though, it is one or the other because they only have one x chromosome. If x chromosome has o" allele, cat will be orange and vice versa if the allele is.