1. The student is expected to: 5A describe the stages of the cell cycle, including deoxyribonucleic acid (DNA) replication and mitosis, and the importance of the cell cycle to the growth of organisms

2. KEY CONCEPT Cells have distinct phases of growth, reproduction, and normal functions.

3. The cell cycle has four main stages.
The cell cycle is a regular pattern of growth, DNA replication, and cell division.

4. The main stages of the cell cycle are gap 1, synthesis, gap 2, and mitosis.
Gap 1 (G1): cell growth and normal functions
DNA synthesis (S): copies DNA
Gap 2 (G2): additional growth
Mitosis (M): includes division of the cell nucleus (mitosis) and division of the cell cytoplasm (cytokinesis)
Mitosis occurs only if the cell is large enough and the DNA undamaged.

5. Cells divide at different rates.
The rate of cell division varies with the need for those types of cells.
Some cells are unlikely to divide (G0).

6. Limits to cell growth
DNA “overload”: The larger a cell becomes, the more demands the cell places on its DNA.
DNA stores the information that controls body functions
When a cell is small, DNA can easily control the cell’s functions and meet its needs.
When a cell is large, it still only has one copy of DNA, so it is more difficult for the cell to perform its functions.

7. Limits to cell growth Exchanging materials:
Large cells have more trouble moving substances across the cell membrane.
If a cell is too large, it is difficult to get enough oxygen and nutrients in and waste products out

8. Division of the Cell When a cell gets too large, it :
1. makes a copy of its DNA (replication),
and then…
2. divides to form two “daughter” cells.

9. Cell size is limited.
Volume increases faster than surface area.

11. Surface area to volume ratios6 1
1 X 1 X 1 cube SA:______ volume: _____
2 X 2 X 2 cube SA:______ volume: _____
10X10X10 cube SA:______ volume: _____
So when volume doubles, the surface area cannot “keep up” with it 8 24
600
1,000

12. Surface area must allow for adequate exchange of materials.
Cell growth is coordinated with division.
Cells that must be large have unique shapes.

13. The student is expected to: 5A describe the stages of the cell cycle, including deoxyribonucleic acid (DNA) replication and mitosis, and the importance of the cell cycle to the growth of organisms

14. KEY CONCEPT Cells divide during mitosis and cytokinesis.

15. Before a cell gets too big, it will divide to form two “daughter cells”
Before a cell divides, it makes a copy of its DNA for each daughter cell.

16. Cell Division
Cell division in eukaryotes is more complex than in prokaryotes.
There are two stages of eukaryotic cell division
Mitosis: Division of the cell nucleus
Cytokinesis: Division of the cell cytoplasm

17. 3. Unicellular organisms reproduce asexually by mitosis or something similar to mitosis (prokaryotes cant do mitosis!)
a. The daughter cells are identical to the parents cells

18. Asexual Reproduction Is one cell reproducing by itself Two types:
Binary Fission: organism replicates its DNA and divides in half, producing two identical daughter cells
Example: bacteria
Budding: asexual process by which yeasts increase in number

19. Budding
Binary Fission

20. Chromosomes Chromosomes are made of condensed chromatin.
Chromatin consists of DNA and the proteins it is wrapped around.
The cells of every organism have a specific number of chromosomes
Ex. humans have 46 chromosomes

22. Chromosomes condense at the start of mitosis.
DNA wraps around proteins (histones) that condense it.
DNA double helix
DNA and histones
Chromatin
Supercoiled DNA

23. DNA plus proteins is called chromatin.
chromatid
telomere
centromere
One half of a duplicated chromosome is a chromatid.
Sister chromatids are held together at the centromere.
Telomeres protect DNA and do not include genes.
Condensed, duplicated chromosome

24. At the ends of each chromatid is an area called the telomere.
The telomere is filled with non-coding DNA
Like a protective cap
Gets shorter during each cell division
Shortening is believed to be linked to aging
Telomeres

25. Chromatin v. chromosomes

26. Before cell division, each chromosome is replicated (meaning copied)
Chromosomes are only visible during cell division, when they are condensed. The rest of the time the chromatin is spread throughout the nucleus.
Before cell division, each chromosome is replicated (meaning copied)
When a chromosome is replicated, it consists of two identical “sister” chromatids.
When a cell divides the chromatids separate, and one goes to each of the two new cells.
Sister chromatids are attached to each other at the spot called the centromere.

27. Interphase prepares the cell to divide.
Mitosis and cytokinesis produce two genetically identical daughter cells.
Parent cell
centrioles
spindle fibers
centrosome
nucleus with
DNA
Interphase prepares the cell to divide.
During interphase, the DNA is duplicated.

28. The Cell Cycle
When a cell is NOT dividing, it is said to be in interphase.
The series of events that a cell goes through as it grows and divides is called the cell cycle.

30. Events of the cell cycle
Interphase, when the cell is NOT dividing, has three phases: G1, S, and G2.
 G1 phase: period of activity in which cells do most of their growing.
a.     Cells increase in size
b.     Cells synthesize (make) new proteins and organelles
S phase: DNA (chromosomes) is replicated
G2: organelles and molecules required for cell division are produced

32. M phase is the phase of cell division. This includes:
1. Mitosis, the division of the cell nucleus, which is made up of four segments including prophase, metaphase, anaphase, and telophase.
2. Cytokinesis, or the division of cytoplasm.

33. M phase
G2 phase
S phase
G1 phase

34. Mitosis divides the cell’s nucleus in four phases.
During prophase, chromosomes condense and spindle fibers form.

35. Mitosis
There are four phases in mitosis:
1.     Prophase
a. Longest phase in mitosis (take % of total time mitosis requires) b.     Chromosomes become visible because they are condensed

36. e. Nuclear envelope breaks down
c.    Centrioles become visible on opposite sides of the nucleus
i. The centrioles help organize the spindle, a structure made of microtubules that helps separate the chromosomes
ii. Chromosomes attach to the spindle fibers near the centromere
iii.      Plant cells to not have centrioles but do have mitotic spindles
d.     Nucleolus disappears
e.    Nuclear envelope breaks down

38. Mitosis divides the cell’s nucleus in four phases.
During metaphase, chromosomes line up in the middle of the cell.

39. 2. Metaphase. a. Chromosomes line up in the center of. the cell. b
2. Metaphase a.     Chromosomes line up in the center of the cell b. Microtubules connect to the centromeres

40. Mitosis divides the cell’s nucleus in four phases.
During anaphase, sister chromatids separate to opposite sides of the cell.

41. 3. Anaphase
a.     Centomeres split and the sister chromatids separate and become individual chromosomes
b.      Chromosomes move and separate into two groups
near the spindle
c. Anaphase ends when the chromosomes stop moving

42. Mitosis divides the cell’s nucleus in four phases.
During telophase, the new nuclei form and chromosomes begin to uncoil.

43. 4. Telophase
a. Chromosomes change form being condensed to dispersed b. A nuclear envelope forms around each cluster of chromosomes c.   Spindle breaks apart d. Nucleolus is visible in each daughter nucleus
Telophase in the midbodies of two daughter cells

44. Cytokinesis differs in animal and plant cells.
In animal cells, the membrane pinches closed.
In plant cells, a cell plate forms.

45. Cytokinesis Mitosis occurs within the cytoplasm of one cell.
Cell division is complete when the cytoplasm divides.
In plants, a structure called the cell plate forms between the two daughter nuclei. The cell plate develops into a cell membrane and cell wall.

46. Cytokinesis
In animal cells, the cell membrane is drawn inward until the cytoplasm is pinched into two equal parts. Each part has a nucleus and cytoplasmic organelles.
The cleavage of daughter cells is almost complete; this is visualized by microtubule staining

49. Interphase Cytokinesis Telophase
Centrioles
Chromatin
Interphase
Nuclear envelope
Cytokinesis
Nuclear envelope reforming
Telophase
Anaphase
Individual chromosomes
Metaphase
Centriole
Spindle
Chromosomes (paired chromatids)
Prophase
Centromere
Spindle forming

51. The student is expected to: 5A describe the stages of the cell cycle, including deoxyribonucleic acid (DNA) replication and mitosis, and the importance of the cell cycle to the growth of organisms; 5B examine specialized cells, including roots, stems, and leaves of plants; and animal cells such as blood, muscle, and epithelium;

52. (Continued) 5C describe the roles of DNA, ribonucleic acid (RNA), and environmental factors in cell differentiation; 5D recognize that disruptions of the cell cycle lead to diseases such as cancer; 9C identify and investigate the role of enzymes

53. KEY CONCEPT Cell cycle regulation is necessary for healthy growth.

54. Regulating the Cell Cycle
Different cell types divide at different rates.
Examples:
Muscle cells and nerve cells do not divide once they have developed.
Skin cells and cells in the bone marrow that make blood cells divide rapidly.

55. Regulating Cell Divisions
Internal regulators – Signals from within the cell to regulate the cell cycle.
They make sure everything is complete before moving on.

56. Regulating Cell Divisions
External regulators – Stimulate or suppress cell growth by recognizing the surrounding situation.
Injury repair
Embryonic stem cell differentiation

57. Internal and external factors regulate cell division.
External factors include physical and chemical signals.
Growth factors are proteins that stimulate cell division.
Most mammal cells form a single layer in a culture dish and stop dividing once they touch other cells.

58. Two of the most important internal factors are kinases and cyclins.
External factors trigger internal factors, which affect the cell cycle.

59. Proteins called Cyclins are present when the cell is dividing and are absent when the cell is not dividing.
They regulate the timing of the cell cycle

60. Controls on cell division
Cell growth and cell division can be turned on and off.
When you are injured your cells divide rapidly to repair the injury. When the injury has healed, the cells stop dividing.

61. Apoptosis is programmed cell death.
a normal feature of healthy organisms
caused by a cell’s production of self-destructive enzymes
occurs in development of infants
webbed fingers

62. Uncontrolled cell growth
When cells in your body CANNOT control cell growth and division, cancer may form.
Cancer cells cannot respond to the signals that regulate the division of cells.
When cancer cells have been dividing uncontrollably, tumors form.
Tumors can damage surrounding tissue.
Cells from tumors can break free and travel to other parts of the body, forming new tumors.

63. Cell division is uncontrolled in cancer.
Cancer cells form disorganized clumps called tumors.
Benign tumors remain clustered and can be removed.
Malignant tumors metastasize, or break away, and can form more tumors.
cancer cell
bloodstream
normal cell

64. Cancer Cancer cells tend to have a damaged oncogene.
This gene possess the information needed to respond to internal and external regulators.

65. During the Reading Metastasis : Benign: 3. Malignant:
Define the following
Metastasis :
Benign:
3. Malignant:
The process or condition of abnormal cell migration and tissue invasion.
Cells that stay where they are usually considered as a Tumor. (Not Cancer)
Cells can break off and infect other areas of the body (Cancer)

67. There are several reasons that cells may lose the ability to control growth.
Examples:
1. smoking
2. radiation exposure
3. viral infection
Scientists who study cancer are researching how cells divide.

68. Cancer cells do not carry out necessary functions.
Cancer cells come from normal cells with damage to genes involved in cell-cycle regulation.

69. Carcinogens are substances known to promote cancer.
Standard cancer treatments typically kill both cancerous and healthy cells.

70. Reviewing Mitosis

71. When does the following occur?
(Name the phase of the cell cycle. If it is in mitosis, name the phase of mitosis)
1. Sister chromatids separate.
2. Chromosomes line up across the center of the cell.
3. The cell’s DNA molecules are copied.
4. The cytoplasm pinches in half.
5. A spindle forms.
Mitosis - Anaphase
Mitosis - Metaphase
S Phase
Cytokinesis
Mitosis - Prophase

72. What are the structures shown
What are the structures shown? How many copies of the cell’s DNA are shown here?
A. Sister chromatids
B. Centromere 2

73. Interphase ? Phase Mitosis Cytokinesis ? ? ? ? Cell Cycle M Phase
Prophase
Metaphase
Anaphase
Telophase

74. What is the name of the structure labeled:
Centriole
Chromosome
Spindle fiber

75. If your were to examine a sample of 1000 cells undergoing mitosis, in which of the phases listed below would you expect to find most of the cells?
A. Prophase
B. Metaphase
C. Anaphase
D. Telophase