1. Karyotyping Sex-Linked Traits and Pedigrees! Oh My!

2. KARYOTYPE SEX CHROMOSOMES: X and Y – determine the sex of an organism. –XX = female –XY = male AUTOSOMES: 22 pairs of chromosomes that do not determine sex. chart of the chromosomes an individual has.

3. Sex Linked Traits SEX LINKED TRAIT: found on the X chromosome AUTOSOMAL TRAIT: exists on any chromosome that does not determine the sex of the organism.

4. Color Blindness Sex linked, recessive condition Alleles: –X c = color blind –X C = normal vision Carrier: has a color blind allele but does not express the trait (has normal vision). –XCXc–XCXc

6. Problem: Sex linked If a woman who is a carrier of the gene for color blindness mates with a man with normal vision, what offspring will result? X C X C – female normal X C X c – femal carrier X C Y – male normal X c Y – male color blind X C X c XCYXCY XCXCXCXC XcYXcY XCXcXCXc XCYXCY

7. Pedigrees A graphic representation of an individual’s family tree Used to recognize patterns of inheritance

8. When are pedigrees used? When testcrosses cannot be made When number of offspring is too small Or if results of testcross would take too long

9. Pedigree Symbols  male – unaffected male – affected  female – unaffected female – affected - marriage - offspring