1. Mitosis and Meiosis Books
Today you will make a meiosis book. The front cover will just have the title and your name.
Pages 1-2 Vocabulary
Page 3 Chromosome Structure
Page 4 Mitosis Table of Contents
Page 5 Interphase
Page 6-10 Phases of Mitosis and Cytokinesis
Page 11 Meiosis Table of Contents
Page 12 Interphase
Page on Phases of Meiosis
Page 21 Cytokinesis
Page 22 Compare Mitosis and Meiosis

2. Meiosis
Cell division where one diploid cell (2n) produces four haploid (n) cells called sex cells or gametes
These cells have half the number of chromosomes as a body cell of a parent

3. Meiosis vocabulary What is a gamete?
Male and female sex cells; the sperm and egg
What is the male gamete?
Sperm; has 23 chromosomes
What is the female gamete?
Egg; has 23 chromosomes

4. Meiosis vocabulary… What is a zygote?
A fertilized egg – has a diploid number (2n) of chromosomes
What is sexual reproduction?
The pattern of reproduction that involves the production and fusion of haploid sex cells
What is a diploid cell?
Cell containing two of each kind of chromosome from the parent

5. Meiosis vocabulary… What is a haploid cell?
Cell containing one of each kind of chromosome from the parent
What is an allele?
Gene form for each variation of a trait of an organism. Example: gene for height can express tall or short
Homologous chromosomes:
Pairs of like chromosomes even though the alleles may be different – so they are not identical chromosomes – sibling variation

6. Coils up into chromosomes
Duplicates itself
Coils up into chromosomes
Chromatin

7. Interphase—period of cell growth and development
DNA replication (copying) occurs during Interphase
During Interphase the cell also grows, carries out normal cell activities, replicates all other organelles
The cell spends most of its life cycle in Interphase

8. Phases of Mitosis
Prophase Metaphase Anaphase Telophase

9. Prophase Chromosomes coil up Nuclear envelope disappears
Spindle fibers form

10. Metaphase—(Middle) Chromosomes line up in middle of cell
Spindle fibers connect to chromosomes

11. Anaphase—(Apart) Chromosome copies divide
Spindle fibers pull chromosomes to opposite poles

12. Telophase—(Two) Chromosomes uncoil Nuclear envelopes form
2 new nuclei are formed
Spindle fibers disappear

13. Cytokinesis — the division of the rest of the cell (cytoplasm and organelles) after the nucleus divides
In animal cells the cytoplasm
pinches in
In plant cells a cell plate forms
After mitosis and cytokinesis, the cell returns to Interphase to continue to grow and perform regular cell activities

14. The Phases of Meiosis Interphase Meiosis I Meiosis II Prophase I
Crossing Over
Metaphase I
Anaphase I
Telophase I
Meiosis II
Prophase II
Metaphase II
Anaphase II
Telophase II

15. Interphase Carries out metabolic activities of the cell
Replicates its chromosomes
Precedes meiosis 1

16. Prophase I Chromosomes coil up and spindle form
Homologous chromosomes pair up and a four-part structure called a tetrad forms

17. During prophase I…
Tightly wound tetrads get so close to one another that the genetic material from one homologous pair exchanges with the other creating new combinations of alleles in the genetic code
Nuclear membrane disappears
Nucleolus disappears

18. What is crossing over?
Exchange of genetic material by non-sister chromatids during prophase I
Results in new combinations of alleles

19. Metaphase I Tetrads line up at the equator
Homologous chromosomes are lined up in pairs along the midline or equator of the cell
Spindle fibers attach to the centromere on each pair
The pairs are not attached to each other

21. Anaphase I
Homologous chromosomes are separated and pulled to opposite poles of the cell
The centromeres do not split during this phase
Each new cell receives only one chromosome from each homologous pair

23. Telophase I Spindle breaks down Chromosomes uncoil
Cytoplasm divided in 2
Each cell has half the genetic information from the original cell
Chromosomes are still doubled containing two sister chromatid
Nuclear membrane reforms
Two diploid daughter cells formed

25. Meiosis II Is there an interphase in Meiosis II?
No. Chromosomes do not replicate
The cells go directly from meiosis I to meiosis II

26. Prophase II Spindle forms in each of the two new cells
Chromosomes are still coiled as sister chromatids
Nuclear membrane disappears
Nucleolus disappears

27. Metaphase II Chromosomes line up at the equator of the cell
Spindle fibers attach to the centromeres

28. Anaphase II Centromeres split
Spindle fibers pull separated chromatids to opposite poles of the cell

29. Telophase II Spindle fibers disappear Chromosomes uncoil
Nuclear membrane reforms
Nucleolus reforms
Cytoplasm divides
Each cell now has half the chromosomes that its parents had
Four daughter haploid cells are formed

31. What are the two divisions of meiosis?
Meiosis I and Meiosis II
Meiosis I
When homologous chromosomes come together and separate
Meiosis II
The division that results in 4 daughter cells, each with half the chromosomes present in the original cell

32. What is genetic recombination?
Genetic variation due to crossing over and random assortment
How many ways can the chromosomes line up? 2

33. How do you find the total number of different kinds of sperm and egg that can be produced?
Take the number of pairs and place it as the exponent with a base of 2
Example: in humans there are 23 pairs of chromosomes
For sperm: 223 = over 8 billion
For egg: 223 = over 8 billion

34. What is the total when fertilization occurs?
223 * 223 = 70 trillion zygotes are possible