1. Cellular Reproduction
Chapter 9
Cellular Reproduction

2. Why do cells need to reproduce?

3. Why are cells so small?

4. How is the surface area represented in a cell?
What is Surface Area?
How is the surface area represented in a cell?

5. What happens when the volume of a cell increases?
What is Volume?
What happens when the volume of a cell increases?

6. Mini-Lab 9.1 Investigate Cell Size
Cell Surface Area
(L x W x 6)
Cell Volume
(L x W x H)
Cell 1 m
Cell 2
0.001 m
Cell 3
2.5 cm (0.025 m)
Cell 4
30 cm (0.3 m)
Cell 5
15 m

7. Cell
Cell Size
Cell Surface Area
(L x W x 6)
Cell Volume
(L x W x H)
SA : V
Cell 1 m
300, 000 : 1
Cell 2
0.001 m
6000 : 1
Cell 3
2.5 cm (0.025 m)
240 : 1
Cell 4
30 cm
(0.30 m)
0.54
0.027
20 : 1
Cell 5
15 m
1350
3375
1 : 2.5

8. Limits to Cell Size Smaller cells can better:
exchange nutrients and expel wastes across the plasma membrane.
higher surface area to volume ratio (SA:V)
transport substances within the cell.
diffusion
motor proteins
communicate instructions for cellular functions.
signal proteins

9. Events of the Cell Cycle
During the cell cycle, the cell grows, replicates its DNA, and divides into two daughter cells. DNA synthesis takes place during the S phase. Cell division takes place during the M phase. G1 and G2 are gap phases.

10. Cell Division
When a cell reaches its maximum size, the nucleus initiates cell division.
Cell division – the splitting of a single cell into two cells.
‘Big Bang’ by M. Ormestad ©2006 All rights reserved

11. Cell Division Cells divide so that an organism… can grow.
increases mass of organism
changes organism - differentiation
can repair damaged cells and tissues.
regeneration
maintenance
can reproduce.

12. The Cell Cycle process of growing and dividing repeated continuously
creates two cells from one cell
normal animal cells - takes hours
3 main stages
interphase
mitosis
cytokinesis

13. Interphase
period of time during which the cell grows, carries out cellular functions, and makes copies of its DNA in preparation for cell division
3 parts (substages)
G1 – gap 1
S – synthesis
G2 – gap 2

14. Chapter 9.2
Mitosis and Cytokinesis

15. Mitosis & Cytokinesis Mitosis Cytokinesis
the cell’s nuclear material divides
4 parts (substages)
Cytokinesis
the cell cytoplasm is divided into two daughter cells

16. Chromosomes
structures that contain the genetic material of an organism
only visible during mitosis
formed when chromatin is wound tightly around proteins called histones

17. Why Chromosomes?
Cell must insure that each new daughter cell gets a complete copy of the cell’s DNA.
Accomplished by:
Duplicating each chromosome during the S-phase of the cell cycle.
Holding these two copies (sister chromatids) together by a ring of proteins called cohesins.
Condensing the chromosomes into a compact form.
Separating the sister chromatids and
Distributing these equally between the two daughter cells.
Inage courtesy of J. R. Paulson and U. C. Laemmli

18. Chromosome Structure sister chromatids centromere telomeres
identical copies
copies created during synthesis of interphase
attached at beginning of mitosis
centromere
Structure where the sister chromatids are attached
telomeres
associated with programmed cell death

19. Stages of Mitosis Prophase Metaphase Anaphase Telophase
Human cell undergoing cytokinesis from M. Pines, Inside the Cell: The New Frontier of Medical Science. U.S. Dept. of Health, Education, and Welfare, 1978.

20. Prophase 1st stage longest Chromosomes condense
Spindle apparatus forms
mitotic spindle
centrosome
centrioles
Nuclear membrane disintegrates
Nucleolus disappears
Chromosomes attach to spindle apparatus

21. Metaphase
2nd stage
shortest
sister chromatids pulled by motor proteins along the spindle apparatus toward the center of the cell
line up along the middle, or equator

22. Anaphase 3rd stage sister chromatids are pulled apart
spindle apparatus microtubules shorten
separates chromatids into two identical sets

23. Telophase 4th & last stage
“opposite of prophase”
Chromosomes arrive at poles of spindle apparatus
decondense
Nuclear membrane and nucleolus reform
Spindle apparatus is broken down or recycled
May occur simultaneously with cytokinesis

24. Another Look at Mitosis

25. Cytokinesis division of the cytoplasm into two daughter cells
Animal cells
microfilaments constrict
cell membrane pinches cell in two
cleavage furrow
Plant cells
construct a cell plate
new cell wall forms on either side of cell plate
Prokaryotic cells
DNA copies attach to plasma membrane
plasma membrane grows and pulls DNA copies apart
cell membrane pinches into two cells

26. Mitosis in Motion http://www.johnkyrk.com/mitosis.html
mitosis.html