1. Cell Growth and Division
Biology
Unit 4
Ms. Lew

2. Vocabulary (p. 90-91) Cell Cycle Chromatin Chromosome DNA overload
Interphase
Sister Chromatid
Spindle Fiber

3. Key Concept:
Most living things grow by __________________________. On average, the cells of an adult animal are ______________ the cells of a young animal.
Making more cells
No larger than

4. List two reasons why cells divide rather than continue to grow larger:
DNA Overload
__________________________________
Exchanging Materials

5. DNA Overload:
DNA overload is when the DNA has too many tasks to do (such as making proteins) and not enough DNA to get the job done efficiently. To prevent DNA overload cells stay small to limit a cells work load.

6. Materials exchange becomes more difficult in large cells:
Materials move into and out of cells Cells need to take in materials such as oxygen, water and glucose. Cells need to get rid of materials such as carbon dioxide, salts, other waste.
Large cells lose efficiency in this process – surface area and volume do NOT increase at the same rate.

7. How do you determine the surface area of a cube?
Length x Width x 6

8. How do you determine the volume of a cube?
Length x Width x Height

9. How do you determine the ratio of surface area to volume?
Surface Area / Volume

10. Why is the ratio of surface area to volume in a cell important?
This ratio is what determines HOW MANY and HOW FAST substances can enter the cell. As a cell grows, its SA/V ratio DECREASES, and the cell can no longer be supplied enough nutrients, and stops growing

11. Door analogy
More doors, less time it takes for people to get out of classroom.

12. Ratio of Surface Area to Volume
Find the surface area, volume and surface area to volume ratio of the following cube-shaped cells:
2cm
4cm
6cm
Surface Area
Volume
Ratio of Surface Area to Volume
24 cm2
96 cm2
216 cm2
8 cm3
64 cm3
216 cm3
3:1
1.5:1
1:1

13. Vocabulary (p. 90-91) Must find definitions on your own by Notebook check #2
Cell Cycle
Chromatin
Chromosome
DNA overload
Interphase
Sister Chromatid
Spindle Fiber
Interphase
Sister Chromatid
Spindle Fiber

14. What is the cell cycle?
During the cell cycle, a “parent” cell grows and divides to form 2 “daughter” cells.
The cycle has three main stages
Interphase
Mitosis
Cytokinesis

15. Remember the two reasons why cells divide rather than continue to grow larger:
DNA Overload
__________________________________
Exchanging Materials

16. The Cell Cycle
Animation

17. G1 M S G2

18. Interphase – G1 , S & G2 During Interphase cells:
Grow to mature size
Mitochondria and chloroplasts are duplicated
Replicate (copy) DNA
Each cell needs instructions
Prepare for cell division
Cell grows
Most of a cells life is spent in Interphase.

19. Chromosomes Are made of DNA
Each chromosome consists of sister chromatids attached at a centromere
Each sister chromatid is an exact copy

20. Mitosis – M phase P M A T The cells nucleus divides into two nuclei
There are four phases
Prophase
Metaphase
Anaphase
Telophase
P M A T

21. Animal Cell Mitosis- Video

22. Prophase 1st stage of Mitosis Chromatin condenses into chromosomes
Centrioles separate and a spindle fiber begins to form.
Nuclear membrane breaks down

23. Prophase

24. Metaphase 2nd Phase of Mitosis
Chromosomes line up in the middle of the cell.
Each chromosome is connected to a spindle fiber.

25. Metaphase

26. Anaphase 3rd Phase of Mitosis
The sister chromatids separate at the centromere and move to opposite ends of the cell.

27. Anaphase

28. Telophase 4th Stage of Mitosis
Chromosomes gather at opposite ends of the cells and lose their shapes (return to chromatin form)
Two new nuclear membranes form, one for each cell.

29. Telophase

30. Stage 3: Cytokinesis The cytoplasm pinches in half.
Each daughter cell has an identical set of duplicate chromosomes

31. Cytokinesis

32. Overview sim

33. Plant cell mitosis

34. And Another one…