1. Phases of MEIOSIS Use this slide show to complete the Meiosis Diagram.
You will need four colors (red, blue, green and orange)

2. Let us begin

3. DNA is in chromatin. Draw a strand in orange
INTERPHASE
DNA is in chromatin. Draw a strand in orange

4. INTERPHASE
Add a strand of blue.

5. INTERPHASE
Add a strand of green.

6. Lastly add a strand of red.
INTERPHASE
Lastly add a strand of red.

7. In prophase I of meiosis, the nucleus disintegrates

8. Chromatin condenses into chromosomes
PROPHASE I
Chromatin condenses into chromosomes

9. Chromosomes find their homologous pairs and “hold hands”
PROPHASE I
Chromosomes find their homologous pairs and “hold hands”

10. PROPHASE I
Homologous pairs are a pair of chromosomes that have the same genes in the same locations. One is maternal (from mom) and one is paternal (from dad)

11. Crossing over is how genetic variation occurs
Crossing over is how genetic variation occurs. Think of it as two chromosomes holding hands and exchanging phone numbers.

12. METAPHASE I
While still holding hands, homologous pairs line up in the middle. Unlike the single file line they make in the middle during mitosis, here it’s a double file line. This double file is called a tetrad.

13. METAPHASE I

14. ANAPHASE I *Cell is Egg Shaped
When the centriolles retract their spindle fibers the homologous pairs are torn away from each other. A full chromosome is pulled to either side, with new genetic information from crossing over.

15. As the cell tears the cleavage furrow forms
TELOPHASE I
As the cell tears the cleavage furrow forms

16. The nucleus begins to reform
TELOPHASE I
The nucleus begins to reform

17. TELOPHASE I
Chromosomes that were pulled to either pole during Anaphase are enclosed in the newly forming nuclei

18. Two cells pop into two new unique cells
Cytokinesis I
Two cells pop into two new unique cells

19. Nucleus begins to disintegrate
PROPHASE II
Nucleus begins to disintegrate

20. METAPHASE II
Spindle fibers attach to centromeres and line chromosomes up in a single file line in the middle (just like metaphase in mitosis)

21. ANAPHASE II
Spindle fibers tear chromosomes into chromatids. Chromatids are pulled to opposite polls of the cell.
(Cells are Egg Shaped)

22. Chromatids are enclosed in newly forming nuclei.
TELOPHASE II
Cells begin to tear and cleavage furrows form.
Chromatids are enclosed in newly forming nuclei.

23. Products are called Gametes or Sex Cells
Final Cytokinesis
Cells pop apart forming 4 new UNIQUE cells with half the amount of DNA as it started.
Products are called Gametes or Sex Cells
(Sperm and Egg)

24. CHROMOSOME NUMBER 2 4 4 4 4 2 each 2 each 1 each
Humans begin with 46 chromosomes before meiosis
each each each

25. CHROMOSOME NUMBER Chromosome number doubles after the first interphase
Meiosis in Mitosis Twice, but it skips the second interphase.
By skipping the second interphase it allows the chromosome number to be halved.
A full set of chromosomes is called DIPLOID.
DIPLOID is 2n
Think Di mean 2
A half set of chromosomes is called HAPLOID.
Haploid is n
Think Hap sounds like half

26. 2nn BEFORE AND AFTER Before meiosis a cell is diploid.
After meiosis is cells are haploid.
2nn

27. Meiosis makes half cells
Two halves make a whole.
Fertilization is when the sperm and egg meet.
When they form they create a zygote

29. How is meiosis different from mitosis?

30. Meiosis vs. Mitosis Sexual or Asexual? What are the products called?
How many cells are produced?
What are the genetics in the product?
Chromosome number?
Unique or Identical?
How many times do they divide?
What happens during first prophase?
What happens during first metaphase?