1. Meiosis! Dec. 7 & 8 Please get: Biology Journal Homework (yellow WS)
BSCS Textbook
White handout

2. Warm Up!
Dihybrid Crosses: What are the four possible allele combinations you would use in a dihybrid cross for a parent with the genotype PpRr? (Hint: Think FOIL)

3. Warm Up Review PpRr…first, outer, inner, last
Combinations: PR, Pr, pR, pr

4. Notes: Meiosis Introduction
Amoeba Sisters on Meiosis Video
Write these questions in your “notes” section and answer during the video:
Why do cells go through the process of meiosis?
How many chromosomes are in the gametes at the end of meiosis?

5. Notes: Meiosis
Meiosis is the process of making gametes (sperm and eggs)
Gametes have half the number (23) of chromosomes of the original cells (46)
Meiosis turns one 46 chromosome cell into four 23 chromosome cells
See any math problems here?!!?

6. Notes Meiosis: How it Happens23 46
Chrom 23 46
Chrom 92
Chrom
Interphase
(Double
Chromosomes) 46
Chrom 23
Meiosis I 23
Meiosis II

7. Guided Reading
Read pages
Complete the guided reading sheet

8. Notes: After Meiosis
A sperm cell and egg cell, each with 23 chromosomes, fertilize to form a zygote. + = The cell of the zygote divides/grows to become an embryo, and eventually a baby! The zygote has 46 chromosomes! 23 23

9. You must half the number of chromosomes to get sperm + egg = 46!
Notes: Muy Importante!
Meiosis is necessary because if you merged two cells with 46 chromosomes each to make a baby, you would get a 92 chromosome mutant!
You must half the number of chromosomes to get sperm + egg = 46!

10. Notes: Why Did Meiosis Evolve?
Sexual reproduction increases the genetic variety in a population
Greater variety = Stronger population
Sexual reproduction always involves the combining of genes from two different organisms to form a zygote
Plants, animals, fungi, protists all go through mitosis

11. Asexual Reproduction
Asexual reproduction also exists in simple organisms, but makes a clone of the parent
This DOES NOT increase genetic variety, but does take less energy
Some organisms do both types of reproduction
Potatoes form sprouts that are clones of themselves.
They can also make seeds/sperm to reproduce with neighboring plants.

12. Meiosis Modeling Get a partner and two different colors of Play-dough
Copy the blank diagram from your guided notes on the whiteboard
Show the process of meiosis for chromosomes #1-2
Use two different colors
Label chromosome # all the way through

13. More labeling! Which two events increase genetic variety in gametes?
Which cells are Haploid? Diploid?