2. Cell Size The size of cell is related to its function
Ex. rbc, wbc, nerve, etc.

3. Cell Size Comparison

5. Chapter 9
Cellular Reproduction
9.1 Cellular Growth
As the cell grows, its volume increases much more rapidly than the surface area.

6. Ratio of Surface Area to Volume
Chapter 9
Cellular Reproduction
9.1 Cellular Growth
Ratio of Surface Area to Volume

7. What are the problems with this?

8. The cell might have difficulty supplying nutrients and expelling enough waste products.
Diffusion over large distances is slow and inefficient. (Small cells maintain more efficient transport systems)

9. Chapter 9
Cellular Reproduction
Cell size affects the ability of the cell to communicate instructions for cellular functions.

10. How do cells avoid these problems?
A few types will stop growing
Most cells will divide (mitosis)

11. Chapter 9
Cellular Reproduction
9.1 Cellular Growth
The Cell Cycle
Cell division prevents the cell from becoming too large.
It also is the way the cell reproduces so that you grow and heal certain injuries.
Cells reproduce by a cycle of growing and dividing called the cell cycle.

12. Cell Cycle Mitosis is only one phase of a cell’s “life”
The cell’s entire “life” is called the cell cycle

13. Cell Cycle

14. The cell cycle consists of three major phases:

15. Chapter 9
Cellular Reproduction
9.1 Cellular Growth
Interphase is the stage during which the cell grows, carries out cellular functions, and replicates.
Mitosis is the stage of the cell cycle during which the cell’s nucleus and nuclear material divide.
Cytokinesis is the method by which a cell’s cytoplasm divides, creating a new cell.

16. Interphase is divided into three smaller phasesG1 S G2

17. The Stages of Interphase
Chapter 9
Cellular Reproduction
9.1 Cellular Growth
The Stages of Interphase
The first stage of interphase, G1
The cell is growing, carrying out normal cell functions.

18. The cell copies its DNA in preparation for cell division.
Chapter 9
Cellular Reproduction
9.1 Cellular Growth
The Second Stage of Interphase, S (synthesis)
The cell copies its DNA in preparation for cell division.

19. The Third Stage of Interphase, G2
Chapter 9
Cellular Reproduction
9.1 Cellular Growth
The Third Stage of Interphase, G2
The cell prepares for the division of its nucleus.

20. Interphase

21. The Stages of Mitosis

22. Prophase The Stages of Mitosis
Chapter 9
Cellular Reproduction
9.2 Mitosis and Cytokinesis
The Stages of Mitosis
Prophase
The cell’s chromatin condenses to form chromosomes
Chromatin: a strand of protein molecules wrapped in DNA

23. Prophase
Chromatin changes from thread-like structure to a rod-like structure
They condense and replicate to form chromosomes

24. Chromosome Structure

25. Chromosomes consist of two identical sister chromatids
Chromatids are held together at a central location called the centromere
At the tips of the chromosomes are telomeres

26. Chromosome Parts

27. Prophase The nuclear envelope disappears.
Chapter 9
Cellular Reproduction
Prophase
The nuclear envelope disappears.
Centrioles appear and begin to move to the opposite ends of the cells (poles)

28. Prophase Spindle fibers form between the centrioles
Spindle fibers: cluster of microtubules that assist with chromosome division

29. Prophase

30. Prophase in Plant Cells

31. Metaphase Chromosomes attach to the spindle fibers at the centromere
Chromosomes line up in the middle of the cell (the equator)

32. Metaphase

33. Metaphase

34. Metaphase in an Animal Cell

35. Anaphase The microtubules of the spindle apparatus begin to shorten.
Chapter 9
Cellular Reproduction
Anaphase
The microtubules of the spindle apparatus begin to shorten.
The sister chromatids separate.
The chromosomes move toward the poles of the cell.

36. Notice: the chromosomes move in the direction of the “arrow”

37. Anaphase in a Plant Cell

38. Chapter 9
Cellular Reproduction
Telophase
The chromosomes arrive at the poles and revert back into chromatin (thread-like)
Two new nuclear membranes begin to form and the nucleoli reappear.
The spindle apparatus disassembles.

39. Telophase in an Animal Cell

40. Chapter 9
Cellular Reproduction
Cytokinesis
In animal cells, microfilaments constrict, or cleave, the cytoplasm.
In plant cells, a new structure, called a cell plate, forms.

41. Cytokinesis in an Animal Cell

42. Cytokinesis in a Plant Cell

43. Beginning of Cytokinesis in an Animal Cell

44. Make an acronym to help you remember the phases of mitosis!!

45. Onion Root Tip Mitosis Lab