1. 10.1 Cell Growth, Division, and Reproduction
Lesson Overview
10.1 Cell Growth, Division, and Reproduction

2. Limits to Cell Size
What are some of the difficulties a cell faces as it increases in size?
The larger a cell becomes, the more demands the cell places on its DNA.
A larger cell is less efficient in moving materials.

3. Information “Overload”
Living cells store critical information in DNA.
As a cell grows, more information is needed.
If a cell were to grow too mcuh, an “information crisis” would occur.

4. Information “Overload”
Compare a cell to a growing town. The town library has a limited number of books. As the town grows, these limited number of books are in greater demand, which limits access.
A growing cell makes greater demands on its genetic “library.” If the cell gets too big, the DNA would not be able to help the growing cell.

5. Exchanging Materials
Material move in and out based on the cell’s surface area.
The rate at which materials are used up depends on the cell’s volume.
The ratio of surface area to volume is key to understanding why cells must divide as they grow.
Food, oxygen, and water enter a cell through the cell membrane. Waste products leave in the same way.

6. Ratio of Surface Area to Volume
-Imagine a cell shaped like a cube.
-As the length increases, its volume increases faster than its surface area.
The SA:V ratio decreases.
If a cell gets too large, the surface area of the cell is not large enough to get enough oxygen and nutrients in and waste out.

7. Traffic Problems
Compare to a town – As the town grows, it becomes more difficult to move information and goods.
Similarly, a cell that continues to grow would experience “traffic” problems. If the cell got too large, it would be more difficult to get oxygen and nutrients in and waste out.

8. Division of the Cell
Before a cell grows too large, it divides into two new “daughter” cells in a process called cell division.
Cell division keeps a stable SA:V ratio.
Cell division reduces cell volume. It also results in an increased ratio of surface area to volume, for each daughter cell.

9. Cell Division and Reproduction
How do asexual and sexual reproduction compare?
-Asexual reproduction – Produce genetically identical offspring from a single parent

10. -Sexual reproduction – Offspring inherit some of their genetic information from each parent.

11. Asexual Reproduction Advantages: Quick, produces many. Disadvantages
Genetically identical / no diversity

12. Sexual Reproduction Advantages: Genetic diversity Disadvantages:
Time, less produced
Diversity good for changing environment

13. Review What are two reasons a large cell is problematic?
-Too much demand on DNA
-Less efficient at moving materials
What ratio decreases as a cell gets larger?
-SA:V

14. Review How many parents are involved in asexual reprod? -One
How do offspring compare to the parent in A.R.?
-They are identical
How many parents are involved in sexual reprod?
-Two
6. How do offspring compare to the parent in S.R.?
-Mix of genes

15. Review Fill in the information below: -Sexual Reproduction -Advantage:
-Genetic Diversity
-Disadvantage
-Takes time

16. Review
8. Fill in the information below: -Asexual Reproduction -Advantage: -Quick and many produced -Disadvantage -No diversity

17. 10.2 The Process of Cell Division
Lesson Overview
10.2 The Process of Cell Division

18. Prokaryotes
Cells carry genetic information in packages of DNA called chromosomes.
Most prokaryotes have only one circular stand of DNA

19. Eukaryotes In eukaryotes, the DNA is wound around a histone protein
Together make a nucleosome.
Chromosomes make the precise separation of DNA during cell division.

20. DNA is condensed to form chromatin, which condense even more to form chromatids, which make up chromosomes.

21. The Prokaryotic Cell Cycle
In prokaryotes, cells go through a process of cell division known as binary fission.
Binary fission = asexual reprod. = Identical offspring

22. The Eukaryotic Cell Cycle
Interphase
The time between cell divisions.
Period of growth that consists of the G1, S, and G2 phases.

23. 1. 4. 3. 2.

24. Interphase G1 phase – cells get larger and make new materials.
S (synthesis) phase – new DNA is synthesized
G2 phase - prepare for cell division
G1- make new proteins and organelles
G2 - many of the organelles and molecules required for cell division are produced.

25. M Phase: Cell Division
In eukaryotes, cell division occurs in two stages: mitosis and cytokinesis.
Mitosis - division of nucleus.
Cytokinesis – division cytoplasm.

26. Mitosis
Cytokinesis

27. Review How many strands of DNA do prokaryotes have? - One
Nucleosomes are made up of what two things?
-DNA wound around a histone protein
Organize “chromatid, chromosomes, DNA, and chromatin” in order from smallest to largest.
-DNA, chromatin, chromatid, chromosome
Prokaryotes go thorugh a process of asex. reprod. called…
- Binary Fission

28. Review What are the four phases of the cycle cycle? - G1, S, G2, M
G1, S, and G2 phases are all part of what?
-Interphase
What two phases make up the M Phase?
- Mitosis and Cytokinesis
What’s the difference between mitosis and cytok.?
-Mitosis – Nucleus splits
-Cytokinesis – Cytoplasm splits

29. Important Cell Structures Involved in Mitosis
Chromatid – each strand of a duplicated chromosome Centromere – the area where chromatids are joined

30. Important Cell Structures Involved in Mitosis
Centrioles – organize the spindle
Spindle – come from centrioles, separate the chromatids

31. Four Steps of Mitosis:
Prophase
Metaphase
Anaphase
Telophase

32. 1. Prophase
Prophase -first phase of mitosis -chromosomes condense and becomes visible.
Centrioles move to opposite sides of nucleu
The nucleolus disappears and nuclear envelope breaks down.

33. 2. Metaphase
Metaphase, -second phase of mitosis -centromeres line up across the center.
A spindle fiber from each pole connects to the centromere.

34. 3. Anaphase
Anaphase -third phase of mitosis -centromeres are pulled apart and each chromatid becomes a separate chromosome.
The chromosomes move towards the poles.

35. 4. Telophase
Telophase, -fourth and final phase of mitosis -chromosomes unwind into chromatin.
Nuclear envelope re-forms around chromosomes.
Spindle breaks apart, and the nucleolus becomes visible in each daughter nucleus.

36. Cytokinesis Not part of mitosis! Part of the M Phase
Cytokinesis completes the process of cell division – it splits one cell into two.

37. Cytokinesis – Animals vs. Plants
Cell membrane is drawn in until the cytoplasm is pinched into two equal parts.

38. Cytokinesis – Animals vs. Plants
In plants, the cell wall prevents pinching.
Instead, a cell plate forms between nuclei and becomes a cell wall.

39. The Stages of the Cell Cycle

40. Review The chromatids are joined at the -Centromere
The spindle is organized by what structures?
- Centrioles
Think of a mnemonic for the 4 stages of mitosis.
-Please Make A Take
Cytokinesis is not part of…
-Mitosis

41. Review Which part of mitosis do chromatids line in the middle?
-Metaphase
6. What part does the chromosomes become visible?
-Prophase
What part does the nuclear envelope start to reform?
-Telophase
What part pulls the sister chromatid apart?
-Anaphase

42. 10.3 Regulating the Cell Cycle
Lesson Overview
10.3 Regulating the Cell Cycle

43. Controls on cell growth and division can be turned on and off.
The Cell Cycle
Controls on cell growth and division can be turned on and off.
For example, when an injury such as a broken bone occurs, cells are stimulated to divide rapidly and start the healing process. The rate of cell division slows when the healing process nears completion.

44. The Discovery of Cyclins
Cyclins - proteins that regulate the cell cycle in eukaryotic cells.
This graph shows how cyclin levels change throughout the cell cycle in fertilized clam eggs.

45. Regulatory Proteins
Internal regulators - respond to events inside a cell.
Allow the cell cycle to proceed only once certain processes have happened.
External regulators - respond to events outside the cell.
Direct cells to speed up or slow down the cell cycle.
Ex - Growth factors – Important during embryonic development and wound healing.
Internal – so anaphase doesn’t happen before metaphase
External – Healing, growing, etc.

46. Apoptosis Apoptosis - programmed cell death.
Plays role in shaping structure.
For example, the foot of a mouse is shaped the way it is partly because the toes undergo apoptosis during tissue development.

47. Cancer and the Cell Cycle
Cancer - disorder in which body cells lose ability to control cell growth.
Cancer cells divide uncontrollably to form a mass of cells called a tumor.

48. Cancer and the Cell Cycle
Benign tumor = noncancerous.
Does not spread to surrounding healthy tissue.
Malignant tumor = cancerous. It spread and destroys surrounding healthy tissue.

49. What Causes Cancer?
Caused by defects in genes that regulate cell growth and division.
Causes include smoking tobacco, radiation exposure, defective genes, and viral infection.
A damaged p53 gene is common in cancer cells.
Causes cells to lose the information needed to respond to growth signals.

50. Treatments for Cancer Some localized tumors can be removed by surgery.
Many tumors can be treated with targeted radiation.
Chemotherapy is the use of compounds that kill or slow the growth of cancer cells.
Cancer Warrior PBS

51. Review When might cell growth be stimulated? - Injury, growth, etc.
Which protein regulates the cell cycle in eukar.?
- Cyclin
Which regulator would prevent anaphase from happening before prophase?
- Internal regulators
What is an example of an external regulator?
-Growth factor

52. Review What is apoptosis? - Programmed cell death
During cancer, cells lose the ability to…
-Control cell growth
What type of tumor is noncancerous?
- Benign
Which damaged gene is commonly found in cancer cells?
- p 53

53. 10.4 Cell Differentiation

54. From One Cell to Many All organisms start a single cell.
Embryo - Early stage of development
During development, an organism’s cells become differentiated and specialized for particular functions.

55. Defining Differentiation
Differentiation - process by which cells become specialized.
Cells differentiate into many different types and become specialized to perform certain tasks.
Differentiated cells carry out the jobs that multicellular organisms need to stay alive.

56. Human Development
Totipotent - able to become everything (a fertilized egg)
After a few days, a human embryo forms into a blastocyst, a hollow ball of cells with a cluster of cells inside known as the inner cell mass.
The inner cell mass are pluripotent – can become many, but not all, of the body's cell types.

57. Stem Cells
Stem cells are unspecialized cells from which differentiated cells develop.
There are two types of stem cells: embryonic and adult stem cells.

58. Embryonic Stem Cells
Embryonic stem cells – found in the inner cells mass.
Embryonic stem cell are pluripotent.
Researchers have grown stem cells isolated from human embryos in culture. Their experiments confirmed that embryonic stem cells have the capacity to produce most cell types in the human body.

59. Adult Stem Cells Adult organisms contain certain stem cells.
Adult stem cells are multipotent – produce a few types of differentiated cells.
Adult stem cells of a given organ or tissue typically produce only the types of cells that are unique to that tissue.

60. Potential Benefits
Stem cell research may lead to new ways to repair the cellular damage that results from heart attack, stroke, and spinal cord injuries.
One example is the approach to reversing heart attack damage illustrated below.

61. Ethical Issues
Most techniques for gathering embryonic stem cells destroy the embryo.
Groups seeking to protect embryos oppose such research as unethical. Other groups support this research as essential to saving human lives and so view it as unethical to restrict the research.
BBC Documentary

62. Review 1. What is the earliest stage of development called? - Embryo
The process by which cells become specialized is…
- Differentiation
3. What is totipotent, pluripotent, and multipotent?
-Totipotent – can become all cells
-Pluripotent – can become most cells
-Multipotent – can become few cells

63. Review 4. Stem cells are cells. -Undifferentiated
Adult stem cells produce cells that are…
-Unique to that tissue
Why is stem cell research important?
-Repair damaged cells and save lives
Why is stem cell research controversial?
-Save embryos vs. save lives