1. Just Meiosis 2018

2. 11.4 Meiosis
homologous - chromosomes in which one set comes from the male parent and the other from the female parent.
match up based on size, gene location, and centromere position

3. SISTER CHROMATIDS ARE DIFFERENT THAN HOMOLOGOUS CHROMOSOMES!

4. diploid cell - contains two complete sets of chromosomes; one from each parent.
Most of cells in the body are diploid.

5. Haploid cell - contains half the number of chromosomes (n) as a diploid (2n) cell
The gametes of sexually reproducing organisms are haploid.
gametes – egg and sperm

7. n - Used to represent the number of chromosomes in a gamete; haploid 2n - n chromosomes from female parent and n chromosomes from the male parent; diploid

8. For the fruit fly, diploid number is 8; 2N = 8, For gametes,
Diploid Cells
For the fruit fly,
diploid number is 8;
2N = 8,
For gametes,
haploid number is 4, N = 4.

9. meiosis - process in reproductive cells which lead to one diploid (2n) cell producing 4 haploid (n) cells that are not genetically identical.

10. The number of chromosomes is reduced because the number of chromosomes per cell are cut in half through the separation of homologous chromosomes.

11. Fertilization - Process by which haploid gametes combine, forming a diploid cell with 2n chromosomes

12. Meiosis Reduces the genetic material by half Why is this necessary?
from mother
from father
child
too
much!
meiosis reduces genetic content

13. Meiosis 1 interphase 2 cell divisions:
Meiosis I consists of : prophase I, metaphase I, anaphase I, telophase I, cytokinesis
Meiosis II consists of: prophase II, metaphase II, anaphase II, telophase II, cytokinesis

14. Before Meiosis I
interphase I cell undergoes a round of chromosome replication and cell prep for division

15. Chapter 10
Sexual Reproduction and Genetics
10.1 Meiosis
Meiosis I
PROPHASE I, replicated chromosomes pair with corresponding homologous chromosomes.

16. tetrad - structure in prophase I when containing duplicated homologous chromosomes are paired; results in four chromatids

17. crossing-over - process in which homologous chromosomes exchange portions of their chromatids during meiosis; only occurs during prophase I

18. metaphase I-
paired chromosomes line up across the center of the cell. (Notice because of crossing over in prophase I, the homologous pairs are a little different than when they first paired)

19. anaphase I
chromosome pairs separate and move toward opposite ends of the cell.

20. telophase I,
nuclear membrane forms around each cluster of chromosomes.
NOTICE THEY ARE NO LONGER PAIRED

21. Cytokinesis then forms two new cells.

22. Meiosis II –neither of the two cells undergo chromosome replication.
Two cells from meiosis one will divide
Result will be 4 cells

23. prophase II
chromosomes become visible.
NOT HOMOLOGOUS CHROMOSOMES;
NOT SISTER CHROMATIDS

24. metaphase II, chromosomes line up in the center of each cell.

25. the paired chromatids separate in both cells.
Anaphase II
the paired chromatids separate in both cells.

26. Telophase II, and Cytokinesis
Each of the four daughter cells produced in meiosis II receives separated chromatids.

27. The final four phases of meiosis II result in four haploid daughter cells.

28. The haploid cells produced by meiosis II are gametes.
Gametes to Zygotes
The haploid cells produced by meiosis II are gametes.
In male animals, these gametes are called sperm.
The female gamete is called an egg in animals.

29. zygote - fertilized egg results in the diploid number restored.

30. In mitosis, when the two sets of genetic material separate, each daughter cell receives one complete set of chromosomes.

32. Mitosis Meiosis Number of cell divisions Replication time
Mitosis
Meiosis
Number of cell divisions
Replication time
Sister chromatids
Homologous chromosomes
Synapsis/Crossing over
Number of chromosomes as a result
No. of Daughter cells
Occurs in what kinds of cells
Purpose 2 1
1 in interphase
1 in interphase
yes
Yes only in interphase I no
Yes, prophase I, Metaphase I, telophase I no
Yes, prophase I only
Diploid 2n
Haploid n 2 4
Body cells
Sex cells
Growth/repair in body cells
Produce gametes