1. Mitosis
Cell Division

2. Agenda
Chromosome Talk
Cell Cycle
Mitosis Overview

3. Mitosis
Division of somatic cells (body)
Daughter Cells
Somatic Cell

4. Why Mitosis? Growth of the individual
Repair and replace damaged tissue (as in healing of a cut)
Reproduce asexually

5. Chromosomes First you duplicate DNA Why?
You have 2 pairs of 23 chromosomes
If cell splits, you will only have 1 pair
Duplicate DNA, cell splits, still have 2 pair
Sex chromosomes- X and Y: XX is female in humans, XY is male

6. Humans have 46 chromosomes
23 chromosomes from each parent.
Most cells (somatic) have the normal number of chromosomes, they are are said to be diploid (i.e. skin cells).
Some cells have half the number of chromosomes are said to be haploid (i.e. egg and sperm cells).

7. The chromosomes from the parents are of the same type, just different variations, so each child has 23 pairs of similar chromosomes.
22 pairs are known as autosomes that contain important genes.
The last pair are known as the sex chromosomes (X and Y) and they have fewer genes and more of an influence on gender.

8. Chromatin in the cell during interphase is structurally loose

9. Stages of Cell Cycle
Mitosis(M phase) –refers to the process of nuclear division
Cytokinesis (C phase)- occurs after mitosis and is the actual physical division of the cell. Not included in mitosis
Interphase: (G1, S, G2)

10. The Cell Cycle G1 Synthesis of DNA for Duplication of chromosomes
Phase of rapid cell growth S
Growth and preparation for cell division
All cells come from preexisting cells
Interphase:
Cells grow, make structural proteins that repair damaged parts, transport nutrients, eliminate wastes, build proteins in preparation for mitosis
Genetic information is called chromatin- all DNA in the nucleus (the tangled fibrous complex of the DNA and protein within a eukaryotic nucleus)
Each chromosome duplicates itself. Each copy is attached together by a centromere. Forming Sister chromatids. Considered one chromosome.
Most time is spent in interphase, nuclear division only a small portion G2 M

11. Interphase
G1: primary growth phase. Increase in proteins and in the number of cell organelles.
S: indicates the synthesis of DNA. a.k.a- DNA replication.
G2: Chromosome condensation, preparation for mitosis; more growth.

12. Mitosis
Inside the Cell
Mitosis

13. Prophase Sister chromatids become visible
Centrioles move to opposite sides of nucleus
the spindle fibres begin to form
nuclear membrane dissolves & disappears

14. Prophase
Photographs from:

15. Metaphase Sister chromatids fully attached to spindle fibres
chromatids line up in the middle of the cell

16. Metaphase
Photographs from:

17. Anaphase
Sister chromatids separate from their partners to become individual chromosomes
pulled by spindle fibres to opposite poles of cell

18. Anaphase
Photographs from:

19. Telophase chromosomes begin to unwind take form of chromatin
spindle fibres dissolve and nuclear membrane forms around the chromosomes

20. Telophase
Q: What did one chromosome say to the other? A: It's telophase, man. UUUNNNNNWWWWWIIIINNNNNDDDD...
Photographs from:

21. Cytokinesis
cell divides the cytoplasm and organelles into two portions
cell membrane cleaves inward
2 identical daughter cells result

22. Cytokinesis
One cell is undergoing mitosis and their neighbor looks over and says 'nice cleavage!' The first cell replies 'You should see my daughter cells!'
Q: Why did the cell where such a tight dress? A: To improve its cleavage furrow.

23. Mitosis Summary Two divisions occur during cell division
Nuclear division (mitosis) and cytoplasmic division (cytokinesis)
During interphase genetic material is replicated
During G1 there are 46 single stranded chromosomes and then after the S phase there are 46 double stranded chromosomes
2 Identical daughter cells produced
Both daughter cells are diploid 2n=46
Embryonic growth is a result of repeated mitotic divisions
A zygote is one cell after fertilization. As divisions occur, specialization occurs.

24. Any Questions?

25. References Edupic Graphical Resource: Cells