3 Karyotype What to look for in a karyotype? When analyzing a human karyotype, scientists first look for these main features:Are there 46 chromosomes?Are there 2 identical pairs of each autosome and 2 sex chromosomes?Are there any rearrangements between chromosomes or large deletions?
4 Chromosomes Humans have 46 chromosomes 44 chromosomes are autosomes 2 are sex chromosomeFemales have two X chromosomesMales have one X and one small Y chromosome
5 PedigreesFEMALEMALEHalf shaded means the person is not “affect”, but is a carrier of the disorderShaded means the person is “affect” by a disorderUnshaded means the person is not “affect”
6 PedigreesMARRIEDTHE SON & HIS WIFETHEIR KIDSTHEIR KIDS
7 Inheritance of sex chromosomes Egg cells contain one X chromosomeSperm cells contain either one X chromosome or one Y chromosomeSo in a human population, half are male and half are female
8 Sex linked GenesGenes located on the sex chromosomes are called sex-linked genes.Males have just one X chromosome, so all X-linked alleles are expressed in Males
9 Sex-Linked Genes What percent of offspring will be girls? What percent of offspring will be boys?What percent of offspring will have normal vision?What percent of offspring will be colorblind?What percent of offspring will be carriers?