1. Section 11.4
Meiosis

2. A) Stages of Meiosis
-Final product will be 4 haploid cells -2 stage process a) Meiosis I b) Meiosis II

3. Meiosis: 2 divisions Result: one copy of each chromosome in a gamete.
Sister
chromatids
separate
Haploid
Diploid
Meiosis I
(reduction
division)
Meiosis II
(equational
Homologs
separate
Result: one copy of each chromosome in a gamete.

4. A) Stages of Meiosis
Interphase- replicate DNA G1 S G2

5. A) Stages of Meiosis
1) Meiosis I a) Prophase (same as Mitosis w/ extra) 1. Synapsis: 2. Crossing over: exchange pieces of _________ btwn homologous pair a) genetic recombination: exchange of

7. Nuclear envelope fragments.
a) Prophase I
Early prophase
Homologs pair.
Crossing over occurs.
Late prophase
Chromosomes condense.
Spindle forms.
Nuclear envelope fragments.

8. Recombination (crossing over)
Occurs in prophase of meiosis I
Generates diversity A a A a B b B b C C c c D D d d E E
Letters denote genes
Case denotes alleles e e F F f f
Creates chromosomes with new combinations of alleles for genes A to F.

9. Chiasmata
Crossing over
or recombination
events create
chiasmata.

10. b) Metaphase I 1. Homolog pairs align along the equator of the cell
2. Sister Chromatids facing opposite poles

11. c) Anaphase II
Homologs separate and
move to opposite poles.
Sister chromatids remain
Attached at their centromeres

12. A) Stages of Meiosis
Metaphase I- 1. __________ line up in the middle of the cell Anaphase I independent assortment: random separation of homologues = ________________

14. A) Stages of Meiosis
d) Telophase I- 1. chromosomes reach poles 2. _____________ takes place 3. 2 new haploid cells created ( 2 copies of chromosomes in each cell)

15. Telophase I Nuclear envelopes reassemble. Spindle disappears.
Cytokinesis divides cell into two.

16. Meiosis I :reduction division
Prophase I
(early)
(diploid)
(late)
Metaphase I
Anaphase I
Telophase I
Nucleus
Spindle
fibers
Nuclear
envelope

17. A) Stages of Meiosis
2) Meiosis II a) Prophase II 1. spindle fibers appear b) Metaphase II 1. chromosomes align in middle of cell c) Anaphase II 1. Sister chromatids move toward poles d) Telophase II 1. nuclear envelope appears & cytokinesis takes place

18. Prophase II
Nuclear envelope fragments.
Spindle forms.

19. Metaphase II
Chromosomes align
along equator of cell.

20. Anaphase II
Sister chromatids separate
and move to opposite poles.

21. Telophase II Nuclear envelope assembles. Chromosomes decondense.
Spindle disappears.
Cytokinesis divides cell into two.

22. A) Stages of Meiosis Results of Meiosis:
______ Haploid cells are created
Contains ______ the # of chromosomes as original cell
_________ variation

23. Mitosis Meiosis Number of divisions 1 2 Number of daughter cells 4
Genetically identical?
Yes No
Chromosome #
Same as parent
Half of parent
When
Throughout life
At sexual maturity
Role
Growth and repair
Sexual reproduction

24. B) Formation of Gametes
Animal cell: meiosis occurs in reproductive organs
a) Ex: __________________
Spermatogenesis: production of _______
Oogenesis: production of ________
a) Polar bodies: remaining cells from meiosis

25. Sperm and Egg

27. Oogonium
(diploid)
Mitosis
Primary
oocyte
Meiosis I
Secondary
(haploid)
Meiosis II
(if fertilization
occurs)
First polar body
may divide
Polar
bodies
die
Ovum (egg)
Second
polar body a A X
Mature
egg

28. C) Asexual and Sexual Reproduction
Asexual Reproduction: reproduction of offspring from 1 parent
a) Ex: _____________
Sexual Reproduction: reproduction of offspring by a sex cell from each parent