1. 1/14/15 Objective: How do sex-linked genes produce different inheritance patterns in males and females? Do Now: Take out assigned homework

2. Chromosome Theory of Inheritance -Genes are located on chromosomes and account for inheritance patterns

3. Thomas Morgan and Fruit Flies Discovered that some traits are sex-linked, linked to the X chromosome

4. Gene Locus: the location of an allele of a gene on homologous chromosomes

5. Genetic Linkage Genetic Linkage: Genes close on chromosome, more likely to be inherited together Sex Linkage: Linked to X chromosome

6. Sex Chromosomes -For a male : XY -For a female: XX Autosomes - Chromosomes that are not the sex chromosomes

7. Sex-linked genes -A gene located on a sex chromosome -Most sex-linked genes are found on the X chromosome ONLY, which is larger than the Y chromosome -When doing a cross, use XX for female, XY for male with the trait superscripted

8. Do this cross: In fruit flies, red-eyes is dominant to white eyes. Cross a white eyed female with a red-eyed male. (Keep in mind, alleles are NOT carried on the Y chromosome) Why is the recessive white eye gene more common in male flies?

9. Sex linked disorders In Humans: –Hemophilia and red-green color blindness are sex linked (X-linked) recessive traits *What sex is more likely to inherit this disease? Why?