1. Cell Growth and Reproduction
(Chapter 8.2)

2. Mitosis notes outline Why cells divide
repair/ replace
diffusion too slow
Cell division
begins___ ends___
chromatin vs.
chromosomes (picture and parts)
III. Cell cycle
1. interphase 2. mitosis prophase metaphase anaphase telophase 3. cytokinesis animal vs plant end result=

3. Why do cells need to divide?
To repair and replace old cells!
Cell theory states that all cells come from preexisting cells!

4. Why don’t cells just keep growing?
Diffusion is too slow over long distances
If cells were too large, it would take too long to obtain nutrients and remove wastes

5. Section 8.2 Summary – pages 201 - 210
Cell Division
The process when 2 cells are produced from one cell
Begins with one parent cell
Results in 2 daughter cells identical to the parent cell
Section 8.2 Summary – pages

6. Section 8.2 Summary – pages 201 - 210
Where is genetic material found in a cell?
DNA is found in the nucleus
Chromatin (jumbled strands of DNA)
Chromosomes—when chromatin condenses during cell division, looks like an X
Human body cells have 46 chromosomes.
Section 8.2 Summary – pages

7. Section 8.2 Summary – pages 201 - 210
The structure of eukaryotic chromosomes
Centromere
Sister chromatids
Supercoil within chromosome
Chromosome
Continued coiling within supercoil
Histone H1
Nucleosome
DNA
Section 8.2 Summary – pages

8. Section 8.2 Summary – pages 201 - 210
Cell Reproduction
Cell cycle—sequence of growth and division of a cell, divided into 3 main periods
Interphase >75%
Mitosis
Cytokinesis
Mitosis
Interphase
Cytokinesis
Section 8.2 Summary – pages

9. Centrioles replicate; cell prepares for division
Interphase
G1: cell grows, metabolism occurs
S: DNA replication
(make exact copy)
G2: more growth,
organelles made,
prepares for division
DNA synthesis and replication
Rapid growth and metabolic activity
Centrioles replicate; cell prepares for division

10. Section 8.2 Summary – pages 201 - 210
Mitosis
Process of cell division where 2 identical daughter cells are formed
Divided into 4 phases: prophase, metaphase, anaphase, telophase
Mitosis
Section 8.2 Summary – pages

11. Section 8.2 Summary – pages 201 - 210
1. Prophase: longest phase of mitosis
Chromatin--coils into visible chromosomes
Sister chromatids—doubled strands of DNA held together by a centromere
Sister
chromatids
Centromere
Chromosome
Section 8.2 Summary – pages

12. Section 8.2 Summary – pages 201 - 210
Prophase
Nuclear envelope—begins to disappear and nucleolus disintegrates
Spindle fibers—form from each end of cell
Spindle fibers
Disappearing nuclear envelope
Doubled chromosome
Section 8.2 Summary – pages

13. Section 8.2 Summary – pages 201 - 210
2. Metaphase: shortest phase of mitosis
Doubled chromosomes are lined up along the equator (midline) of the cell
Centromere
Sister chromatids
Section 8.2 Summary – pages

14. Section 8.2 Summary – pages 201 - 210
3. Anaphase
Centromeres split
Chromosomes are pulled apart and separated by spindle fibers
Section 8.2 Summary – pages

15. Section 8.2 Summary – pages 201 - 210
4. Telophase
Cell membrane begins to split cell in 2
Opposite of prophase: spindle disappears and nucleus reappears
Nuclear envelope reappears
Two daughter cells are formed
Section 8.2 Summary – pages

16. Section 8.2 Summary – pages 201 - 210
Cytokinesis
Division of the cytoplasm
In animal cells—
2 cells are separated
by membrane “pinching in”
between them
Section 8.2 Summary – pages

17. Section 8.2 Summary – pages 201 - 210
Cytokinesis
Division of the cytoplasm
In plant cells—
2 cells are separated
by a cell plate that forms
in between them
Section 8.2 Summary – pages

18. Mitosis
Prophase Metaphase Anaphase Telophase

19. Mitosis
Prophase Metaphase Anaphase Telophase

20. Mitosis results in….
2 new daughter cells IDENTICAL to the parent cells
Remember: cells→tissue→organ→organ system

21. Section 8.2 Summary – pages 201 - 210
Results of Mitosis
Click image to view movie.
Section 8.2 Summary – pages