1. Sex-Linked Traits Chapter 4.1

2. Answers to Questions 1. What are sex-linked traits? - Human traits that are carried on the sex chromosomes. 2. What’s a carrier? - A person who has one recessive allele for a trait and one dominant allele. 3. Males have one X chromosome. Males will be color- blind if they have one allele, and females need two recessive alleles to be colorblind.

4. Sex-determination  Autosomes --- Non-sex chromosomes; 22 pairs or 44 individual chromosomes.  23 rd pair --- Sex chromosomes; determines gender. XX --- female XY --- male

5. Sex-influenced Traits  Expressed differently in both sexes due to different hormones which are determined by different sets of genes.  Examples --- male-pattern baldness, horn size in mountain sheep, and feather color in peacocks.

6. Sex-linked Traits  Traits found on sex chromosomes.  2 traits that are X-linked inheritance in humans are certain forms of color-blindness & hemophilia.  Hemophilia --- blood disorder where your blood doesn’t clot.