1. Determining the Basis of Life
Chapter 6
Lesson 4

2. Lesson Introduction What is meiosis? How is it different than mitosis?
How is meiosis important to genetic variation?
What things occur during meiosis to guarantee genetic variation?

3. Meiosis Cell division used in the sexual reproduction of organisms
One parent cell produces 4 daughter cells
Parent cell = original cell
Daughter cells = newly produced cells
Each daughter cell will have half the number of chromosomes as the parent cell

4. Meiosis Parent cell has 2 chromosomes for each loci
Loci = numbered location of chromosomes in an organism
Example: Humans have 23 loci
Each cell has 46 chromosomes
23 came from mother
23 came from father

5. Meiosis Terminology Homologous Chromosomes Diploid cell
2 chromosomes at the same loci (1 from each parent)
Diploid cell
Cells containing homologous chromosomes for each loci
Normal body cells

6. Meiosis Terminology Haploid cell Zygote
Cells with 1 chromosomes for each loci (reproductive cells)
Zygote
Diploid cell that forms after 2 haploid reproductive cells fuse (join)

7. Meiosis Stages
Completes the same stages as mitosis, but does so 2 times.
Stages
Meiosis I
Interphase
Prophase I
Metaphase I
Anaphase I (eggs stop)
Telophase I
Cytokinesis I
Meiosis II
Prophase II
Metaphase II
Anaphase II
Telophase II
Cytokinesis II

8. Meiosis I Metaphase I Interphase Prophase I Cytokinesis I Telophase I
Anaphase I

9. Meiosis II Metaphase II Prophase II 4 daughter cells, all 1N
Cytokinesis II
Telophase II
Anaphase II

10. Video Clips 1 2 3