1. Genetic Variation Tahquitz High School Always show … that Titan Pride!!

2. How does genetic variation occur? EQ: How do parents with the same genes make offspring that are so different?

3. Meiosis: the process by which the number of chromosomes per cell is cut in half the the separation of homologous chromosomes in a diploid cell How does genetic variation occur?

5. Meiosis Step 1: Chromosome Duplication – Each chromosome is copied in the nucleus of the cell

6. Meiosis Question: The average human has 23 pair of chromosomes. How many pairs will a cell have after chromosome duplication?

7. Meiosis Question: The average human has 23 pair of chromosomes. How many pairs will a cell have after chromosome duplication? 46 pairs

8. Meiosis Question: The average Time Lord has 68 pair of chromosomes. How many pairs will a cell have after chromosome duplication?

9. Meiosis Step 2: Crossing Over – Homologous chromosomes pair together and gene alleles are able to switch with the neighboring chromosome.

10. Meiosis Step 2: Crossing Over – Homologous: chromosomes with same genes, one from each parent – Alleles: one of a number of different forms of a gene

11. Meiosis Step 3: Meiosis I – Homologous chromosomes are separated into 2 sister cells Status Check: How many chromosomes at this stage for the average human? Time lord?

12. Meiosis Step 4: Meiosis II – Homologous chromosome pairs are separated into 2 sister cells with half the amount of chromosome as the original cell. Status Check: How many chromosomes at this stage for the average human? Time lord?

13. Meiosis Step 4: Meiosis II – Creates 4 genetically different haploid cells – Genes are randomly separated into the 4 different cell which is the Principle of Independent Assortment

14. Meiosis Step 4: Meiosis II – Haploid cells: (Greek haplous means single) contain ½ the amount of chromosomes – Diploid cells: (diplo- means double) contains both sets of homologous chromosomes

15. Your Turn Create a Flow Chart showing the steps of meiosis for a mosquito. A mosquito has 6 chromosomes. – Tip: Refer back to your notes – Due: Tomorrow EQ: How do parents with the same genes make offspring that are so different?