1. Biology
Unit 8 – Cell Division
Notes #1 (Chapter 5)

2. Cell Division For cells, bigger is not better
As cells get bigger, volume increases faster than surface area
This makes it difficult for the cell to take in enough nutrients and get rid wastes efficiently
When a cell reaches its max size, the nucleus initiates cell division

3. Results of Cell Division
The cell cycle is important for:
reproduction in some organisms
asexual reproduction = identical offspring
Regeneration (ex – sea star)
Budding
Fission
growth in multicellular organisms
Cell differentiation
Repair replacement of worn out or damaged cells, and repair of damaged tissues.
Lesson 1

4. The Cell Cycle (cont.)
Most cells in an organism go through a cycle of growth, development, and division called the cell cycle.
There are two main phases in the cell cycle—interphase and the mitotic phase.

5. Part 1 -Interphase
Interphase occurs in three stages: G1, S, and G2, and takes up 90% of the time of the cell cycle
G1 (gap 1)
Period of growth, DNA = chromatin
S (synthesis)
Chromosomes replicate
Lesson 1

6. Part 1-Interphase G2 (gap 2) Cell creates organelles
The cell’s DNA is copied during the S stage and is arranged as pairs of identical chromosomes called sister chromatids.
Sister chromatids are held together by a structure called the centromere.
G2 (gap 2) Cell creates organelles
Lesson 1

7. The Mitotic Phase
During mitosis, the contents of the nucleus divide, forming two identical nuclei.
Lesson 1

8. The Mitotic Phase (cont.)
Lesson 1

9. The Mitotic Phase (cont.)
Lesson 1

10. The Mitotic Phase (cont.)
Lesson 1

11. The Mitotic Phase (cont.)
Lesson 1

12. The Mitotic Phase (cont.)
In cytokinesis, the cytoplasm divides (cell membrane folds in) and forms two new daughter cells.
Lesson 1

13. Mitosis

14. Metaphase Hint: Chromosomes are aligned in middle of cell
Name that Stage!
Metaphase
Hint:
Chromosomes are aligned in middle of cell

15. Name that Stage!
Telophase
Hint:
Cell plate is splitting the cell

16. Name that Stage! Interphase Hint:
Two normal looking nuclei of two cells

17. Name that Stage! Prophase Hint:
Chromosomes are forming and the nucleus is gone

18. Name that Stage!
Anaphase
Hint:
Chromatids are being pulled apart

19. Lesson 1

20. Review
In order, name the 5 stages of the cell cycle.
During which interphase stage do organelles replicate?
What do you call the division of the cell’s cytoplasm ?
During which interphase stage is DNA created?
During which stage do spindle fibers form?
During which stage are chromosomes aligned in the middle?
During which stage are chromatids separated?
During which stage does the nucleus dissolve?
What is the result of mitosis?

21. In order, name the 5 stages of the cell cycle.
Interphase, Prophase, Metaphase, Anaphase, Telophase
During which interphase stage do organelles replicate? G1
What do you call the division of the cell’s cytoplasm?
Cytokineses
During which interphase stage is DNA created? S
During which stage do spindle fibers form?
Prophase
During which stage are chromosomes aligned in the middle?
Metaphase
During which stage are chromatids separated?
Anaphase
During which stage does the nucleus dissolve?
What is the result of mitosis?
2 identical (daughter) diploid cells