Karyotyping Sex-Linked Traits and Pedigrees! Oh My!

1. KaryotypingSex-Linked Traitsand Pedigrees!Oh My!

2. KARYOTYPE • chart of the chromosomes an individual has. • 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.

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: • Xc = color blind • XC = normal vision • Carrier: has a color blind allele but does not express the trait (has normal vision). • XCXc

6. XCXc XCXC XCY XcY 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? XC Xc XC Y • XCXC – female normal • XCXc – femal carrier • XCY – male normal • XcY – male color blind

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