1. Cell Division

3. I. Reasons for asexual cell division
A. Growth
B. Repair
C. Reproduction

6. II. Prokaryotes
A. Binary Fission: division of prok. cells into 2 offspring cells
DNA Copied
Cell begins to divide
2 identical haploid cells formed

10. III. Eukaryotes - Mitosis
A. Cytoplasm and nucleus divide
B. Cells go through Mitosis and then Cell division (Cytokinesis)
C. Mitosis: The division of the nucleus.

13. IV. Cell Cycle A. The “life cycle” of the cell
1. Interphase- new cell until mitosis
Time between cell divisions
2. 3 parts: G1, S, G2
A. G1=1st growth, normal cellular activity
B. S= Synthesis- The DNA is copied
C. G2=2nd growth time, getting ready for division

14. Cell Cycle
C. Some cells stay in G1. This is called G0. ( neurons, liver cells)
No replication/division of cells
All cells must go through G1 checkpoints.
The cells have proteins that check to make sure everything is ok before the S phase and moving toward division.

15. Cell Cycle B. Mitosis- “M phase” – nucleus divides
C. Cytokinesis- Splitting of the cytoplasm

18. How does the cell know how to divide?
Cell Division
Reproduction
Growth
Repair
Why do cells divide?
How does the cell know how to divide?
The DNA has the instructions for all of the cell’s activities.

19. Cell Cycle 3 Parts The sequence of development and division of a cell
Interphase - Preparation
Mitosis – Cell division
Cytokinesis – Splitting
Adult human cell: ~24 hrs
18-20 hours in interphase
2 hours in mitosis
Embryonic cells: 30 min.
How long does it take?

20. Interphase What happens Cell doubles in size DNA replicates
Organelles double in number

22. Mitosis: PROPHASE What happens DNA forms chromosomes Spindle forms
Centrioles move toward opposite poles
Nuclear membrane begins to disappear

25. Mitosis: METAPHASE What happens Nucleus has disappeared completely
Chromosomes line up in the middle of the cell “equator”
Spindle fibers attach at centromeres

27. Mitosis: ANAPHASE What happens Centromeres divide
Chromatids separate and move to opposite poles
Spindle fibers retract to poles

29. Mitosis: TELOPHASE What happens
Nuclear membrane forms around each group of chromosomes
Chromosomes unwind
Cytokinesis begins

31. Cytokinesis
Cytoplasm divides
One cell becomes 2 cells
What happens