1. Aim: How does meiosis and fertilization increase variation among offspring?

2. What do these pictures show?

3. Measure your partner’s ear length
Are every bodies ear length the same?
Why not?
Genetic variation

4. Genetic Variation Variation between organisms due to: Meiosis:
crossing over
independent assortment
Fertilization

5. Meiosis Review DNA replicates Prophase I: synapsis & crossing over
1st Division – 2 cells
2nd Division – 4 haploid cells

6. Crossing Over
During meiosis I -homologous pairs line up and and exchange genes

7. Genetic Recombination
During Crossing Over, genes change their location on chromosomes. This change increases genetic variation and leads to offspring with different appearances.

8. Independent Assortment
The chromosomes separate randomly into gametes.

9. What is the result of independent assortment?
Different combinations of genes in gametes

10. Fertilization
During fertilization a mother’s genes (egg) and a father genes (sperm) combine. This combination of genes results in Genetic Recombination.

11. Trillions of possible combinations
Variation

12. Variation What type of cell division leads to variation? How?
How does fertilization lead to genetic variation?