Meiosis and Sex linked Traits
CHROMOSOME # Humans have 23 different chromosomes in each cell Most cells have 2 sets of chromosomes = 46 total
CHROMOSOME # Each pair of similar chromosomes are called homologous 23 homologous pairs in each cell
CHROMOSOME # DIPLOID: 2 sets of chromosomes (one from each parent) 2N --like normal body cells HAPLOID: 1 set of chromosomes (only from one parent) N --gametes (sperm or egg)
WHERE IS HAPLOID FROM? MEIOSIS: cell division that forms gametes Similar to mitosis (2 difference) 1. Meiosis happens twice to same cell 2. Homologous chromosomes split up-so each cell gets 1 set of chromosomes, not 2
SEX-LINKED TRAITS Traits found on sex chromosomes AUTOSOMES: body chromosomes (22 pairs) SEX CHROMOSOMES: X & Y (1 pair only), determine gender MALE: XY FEMALE: XX
SEX-LINKED TRAITS Sperm: have X or Y Egg: have only an X X Y X
SEX-LINKED TRAITS Y chromosome doesn’t have trait Only X chromosome has trait Red = dom White = rec Red female: XRXR or XRXr Red male: XRY White female? White male?
2. XrXr x XRY SEX-LINKED TRAITS White female: XrXr White male: XrY Do crosses on board 1. XRXr x XRY 2. XrXr x XRY
Genetics Knowledge Checkpoint Types of Dominance Incomplete Dominance Means? Example? Codominance Multiple Alleles Sex-Linked Examples? Meiosis Original Cell Genetic Material? Product of Meiosis? What do chromosomes form tetrads? What causes genetic differences among the same chromosomes?