1. Meiosis and Sex linked Traits

2. CHROMOSOME # Humans have 23 different chromosomes in each cell
Most cells have 2 sets of chromosomes = 46 total

3. CHROMOSOME # Each pair of similar chromosomes are called homologous
23 homologous pairs in each cell

4. 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)

5. 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

6. 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

7. SEX-LINKED TRAITS
Sperm: have X or Y
Egg: have only an X X Y X

8. 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?

9. 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

10. 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?