1. Vocabulary- use CH 11 to define these terms.
Homologous chromosomes
Tetrad
Crossing over
Trait
Gene
Allele
Hybrid
Homozygous
Heterozygous
Phenotype
Genotype
Probability

3. Agenda 12/3- Cell Cycle Video clip: mitosis Review lab questions Quiz
Meiosis vocabulary (due tomorrow)

4. Agenda 12/4- Meiosis Quiz Vocab squares- meiosis Notes- meiosis
Modeling crossing over
Sequencing mitosis and meiosis: compare and contrast

5. Eukaryotic Cell Division
Mitosis- somatic (non-reproductive) cell division
Parent cell divides into two identical daughter cells (diploid=2n)
Meiosis- cell division resulting in reproductive cells (gametes)
Parent cell divides into 4 daughter cells, each with half the number of chromosomes (haploid=1n) 5

6. Cell Division Humans have 46 chromosomes, 23 from each parent.
Haploid cells: only one of each chromosome (n)
Diploid cells: two of each chromosome (2n) 6

7. Why don’t you look exactly like your parents or siblings?
Meiosis!
Instead of 2 cells that are identical to the parent cell, as in mitosis, meiosis results in 4 haploid cells that are different from the parent cell and from each other.

8. Why don’t you look exactly like your parents or siblings?
Meiosis!
Sexual reproduction increases genetic variation in a population, which increases a species’ ability to adapt to changes in their environment.

9. Sexual Reproduction
Male gamete (sperm) and female gamete (egg) are haploid (1n)
Fertilization occurs when an egg and a sperm fuse to form a zygote (2n).
Meiosis is the form of cell division that results in gametes.

10. Meiosis produces gametes
4 haploid daughter cells formed
Preceded by interphase and DNA replication
2 divisions
Meiosis I
Meiosis II 10

11. Meiosis- click for video clip
Meiosis I- like mitosis but only one copy of each homologous chromosome goes to each new cell; two new cells formed
Prophase I
Metaphase I- homologous chromosomes line up on equator
Anaphase I- homologous chromosomes separate
Telophase I- two new cells, each with half the genetic material
Meiosis II- the two cells formed in Meiosis I divide again
Basically like Mitosis 11

12. The Human Karyotype
Homologous Chromosomes
chromosome pair, one from each parent, that are similar in length, gene position and centromere location

13. Meiosis I - Reduction Division
Interphase I
Prophase I
Metaphase I
Anaphase I
Each chromosome pairs with its corresponding homologous chromosome to form a tetrad.
Cells undergo a round of DNA replication, forming duplicate Chromosomes.
Homologous chromosomes line up along the middle of the cell.
Spindle fibers attach to the chromosomes.
The fibers pull the homologous chromosomes toward the opposite ends of the cell.

14. Meiosis I - Reduction Division
Interphase I
Prophase I
Metaphase I
Anaphase I
Crossing over- exchange of genetic info between homologous chromosomes- increases genetic variation among offspring
Cells undergo a round of DNA replication, forming duplicate Chromosomes.
Homologous chromosomes line up along the middle of the cell.
Spindle fibers attach to the chromosomes.
The fibers pull the homologous chromosomes toward the opposite ends of the cell.
This reduces the chromosome number in each daughter cell by half.

15. Meiosis II - Similar to Mitosis
Prophase II
Metaphase II
Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original.
The chromosomes line up in a similar way to the metaphase stage of mitosis.
Anaphase II
Telophase II
The sister chromatids separate and move toward opposite ends of the cell.
Meiosis II results in four haploid (N) daughter cells.

16. Modeling Crossing Over
Use paper strips to create a model of crossing over
First, create a pair of homologous chromosomes using two different colors.
Replicate the DNA and hold the sister chromatids together with a paper clip or tape
Materials: scissors, tape, construction paper

17. Agenda 12/5- Meiosis Bellwork- sequencing mitosis and meiosis
Notes- comparing mitosis and meiosis
Video- Life’s Greatest Miracle
Homework- study for unit test (DNA structure and replication, cell cycle, cell division- mitosis and meiosis)

18. Mitosis vs. Meiosis Animation Mitosis- 2 diploid cells produced
Meiosis- 4 haploid cells produced
Why? 18

19. Meiosis Using two successive divisions to reduce the number of chromosomes by half and create gametes.
Homologous chromosomes: a pair of chromosomes with the same genes (but may have different alleles); one from each parent.

20. Mitosis vs. Meiosis Mitosis Meiosis 1 2 4 46 (diploid) 23 (haploid)
# of divisions 1 2
# of daughter cells produced 4
# chromosomes in parent cell
46 (diploid)
# chromosomes in daughter cell
23 (haploid)
Type of cells produced
Somatic (body) cells
Gametes (sex cells)

21. Life’s Greatest Miracle
Video link
Answer the questions on the worksheet

22. Comparing Mitosis and Meiosis
Place the cards in order
How are the two processes similar? How are they different?

23. Chromosomes and Genes
Traits are inherited through genes on chromosomes.
Chromosomes are composed of several hundred to a few thousand genes.
A genes specific location on a chromosome is called a locus (pl. loci).