1. Cellular Reproduction
Chapter 9: Cellular Reproduction

2. Activating Prior Knowledge:
What are chromosomes made of?
Where are chromosomes found in your cell (organelle)?
How many chromosomes are found in each human body cell?
Where did YOUR chromosomes come from?

3. Chromatin and Chromosomes:
Inside the nucleus are fine strands of chromatin = a complex of DNA bound to protein
Chromatin coil up and become densely packed, forming chromosomes
Chromosomes are visible under a microscope when a cell divides

4. Number of chromosomes in a human body cell?
23 pairs of chromosomes = 46 chromosomes total
23 from mom and 23 from dad

5. CYTOPLASM NUCLEUS Where are chromosomes in eukaryotic cells?
In the Prokaryotic cell: Chromosomes are found in the cytoplasm and in Eukaryotic cell: they are located in the nucleus
CYTOPLASM
NUCLEUS

6. Vocabulary: Asexual Reproduction Sexual Reproduction Mitosis Meiosis
Diploid
Haploid
Chromatin
Chromatid
Centromere
Histone
Nucleosomes

7. Asexual Reproduction:
The production of genetically identical offspring from a single parent

8. Sexual Reproduction:
Offspring are produced by the fusion of two sex cells – one from each of two parents. These fuse into a single cell before the offspring can grow.

9. Mitosis: Division of the nucleus of a eukaryotic cell
Followed by cytokinesis –
division of the cytoplasm
The two daughter cells are
identical to the original cell

10. Meiosis:
Process that produces gametes from a diploid cell. A reductive division of the nucleus that produces four haploid gametes.

11. Diploid: Cells having two sets of chromosomes 2N = 46
Examples: All human body cells
Except reproductive cells (sperm and egg)

12. Haploid: Cells containing only one set of chromosomes N = 23
Gametes (egg and sperm)

13. Chromatin:
DNA and protein (histones) in the nucleus of a non-dividing cell

14. Chromatid:
One of the two identical parts of a replicated chromosome

15. Centromere:
Point of attachment between sister chromatids

16. Histone:
Protein molecule that DNA wraps around during chromosome formation

17. Nucleosomes:
The beadlike structures formed by DNA and histone molecules

18. Chapter 9: Cellular Reproduction

19. Activating Prior Knowledge:
List the eight characteristics of living things.
List four differences between plant and animal cells.
Which animal organelle is used in cell division?
Which organelle surrounds the cell membrane in plant cells?
What do we call the jelly-like material within the cell?
What are chromosomes made of?
Where are chromosomes found in your cell (organelle)?
How many chromosomes are found in each human body cell?
Where did YOUR chromosomes come from?
Can you name five types/kinds of cells found in the human body?
Name three differences between prokaryotic and eukaryotic cells.

20. Do you remember any of the eight characteristics of living things?
Living things are based on a universal genetic code (DNA)
Living things grow and develop
Living things respond to their environment (stimulus)
Living things reproduce
Living things maintain a stable internal environment (homeostasis)
Living things obtain and use material and energy (metabolism)
Living things are made up of CELLS
Taken as a group, living things evolve over time

21. Plant vs. Animal Cell wall and cell membrane Large central vacuole
Chloroplast (photosynthesis) and mitochondria (cellular respiration)
Only a cell membrane
Smaller vacuoles
Only mitochondria (cellular respiration)
Lysosomes
Flagella
Centrioles – used in cell division

22. Chromatin and Chromosomes:
Inside the nucleus are fine strands of chromatin = a complex of DNA bound to protein
Chromatin coil up and become densely packed, forming chromosomes
Chromosomes are visible under a microscope when a cell divides

23. Number of chromosomes in a human body cell?
23 pairs of chromosomes = 46 chromosomes total
23 from mom and 23 from dad

24. Where are chromosomes in eukaryotic cells?
CYTOPLASM
NUCLEUS

25. Types of Cells in the body:
Cells - basic unit of structure and function in living things
Cells with a specific structure and function and are found in multi-celled organisms
Examples: skin cells, blood cells, brain cells, bone cells, liver cell, nerve cells, muscle cells, etc.
Brain cells
Blood cells
Liver cells

26. Two categories of cells
Prokaryotic
Eukaryotic
-Nucleus
-Unicellular
-No Nucleus
-Complex
-Cell wall (plants and bacteria)
-Membrane bound organelles
-Less complex
-Smaller Ribosomes less complex
-Cell membrane
-Multicellular
-DNA
- Ribosomes larger and complex
-Cytoplasm
-DNA is circular
-Ribosomes
-DNA is X shaped
-Living things
0.1-10µm
10-100µm

27. Vocabulary: Asexual Reproduction Sexual Reproduction Mitosis Meiosis
Diploid
Haploid
Chromatin
Chromatid
Centromere
Histone
Nucleosomes

28. Asexual Reproduction:
The production of genetically identical offspring from a single parent

29. Sexual Reproduction:
Offspring are produced by the fusion of two sex cells – one from each of two parents. These fuse into a single cell before the offspring can grow.

30. Mitosis: Division of the nucleus of a eukaryotic cell
Followed by cytokinesis –
division of the cytoplasm
The two daughter cells are
identical to the original cell

31. Meiosis:
Process that produces gametes from a diploid cell. A reductive division of the nucleus that produces four haploid gametes.

32. Diploid: Cells having two sets of chromosomes 2N = 46
Examples: All human body cells
Except reproductive cells (sperm and egg)

33. Haploid: Cells containing only one set of chromosomes N = 23
Gametes (egg and sperm)

34. Chromatin:
DNA and protein (histones) in the nucleus of a non-dividing cell

35. Chromatid:
One of the two identical parts of a replicated chromosome

36. Centromere:
Point of attachment between sister chromatids

37. Histone:
Protein molecule that DNA wraps around during chromosome formation

38. Nucleosomes:
The beadlike structures formed by DNA and histone molecules

39. Cellular Growth
Section 9.1

40. Bozeman Science - Why Are Cells Small
THINK ABOUT IT
When a living thing grows, what happens to its cells?
What are some of the difficulties a cell faces as it increases in size?
Bozeman Science - Why Are Cells Small

41. Limits to Cell Size
There are 2 main reasons why cells do not grow indefinitely:
The larger a cell becomes, the more demands the cell places on its DNA.
A larger cell is less efficient in moving nutrients and waste materials across its cell membrane.

42. Limits to Cell Size
Larger cells place more demands on their DNA
When a cell grows, it does not make more copies of its DNA. If the cell grew continuously, there would be information crisis.
When a cell is small, the information stored in DNA is able to meet all of the cell’s needs
It’s like putting a Civic engine in a Hummer… just doesn’t have the power to make it go.

43. 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 serve the needs of the growing cell.

44. Limits to Cell Size
2. Larger cells cannot move enough nutrients and waste across the cell membrane
Function of the cell membrane: help exchange materials between outside and inside of the cell.
A huge cell is going to need a lot of food, water, and oxygen and produce a lot of waste that would have to travel through the cell and across the membrane.

45. Exchanging Materials:
Food, oxygen, and water enter a cell through the cell membrane. Waste products leave in the same way.
The rate at which this exchange takes place depends on the surface area of a cell.

46. Exchanging Materials:
The rate at which food and oxygen are used up and waste products are produced depends on the cell’s volume.
The ratio of surface area to volume is key to understanding why cells must divide as they grow.

47. Ratio of Surface Area to Volume
Imagine a cell shaped like a cube...
As the length of the sides of a cube increases, its volume increases faster than its surface area, decreasing the ratio of surface area to volume.
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.

48. Traffic Problems
To use the town analogy again, as the town grows, more and more traffic clogs the main street. It becomes difficult to get information across town and goods in and out.
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.

49. Division of the Cell
Before a cell grows too large, it divides into two new “daughter” cells in a process called cell division.
Before cell division, the cell copies all of its DNA.
The cell divides into two “daughter” cells.
Each daughter cell receives a complete set of DNA.
Cell division reduces cell volume.
Cell division results in an increased ratio of surface area to volume for each daughter cell.

50. Cell Division and Reproduction
Asexual Reproduction
Sexual Reproduction
A single parent
Genetically identical offspring
Prokaryotes, eukaryotic single-celled organisms (algae, yeast, protozoa), a few multicellular organisms
Simple, efficient, & effective way for an organism to produce a large number of offspring.
Fusion of two sex cells – one from each of two parents
Genetically diverse offspring
Most animals and plants, and many single-celled organisms
Genetic diversity helps ensure survival of species when environment changes

51. Binary Fission in various single-celled organisms (left)
Binary Fission in various single-celled organisms (left). Cell division is a relatively simple process in many single-celled organisms. Eventually the parent cell will pinch apart to form two identical daughter cells. In multiple fission (right), a multinucleated cell can divide to form more than one daughter cell. Multiple fission is more often observed among protists.
Honors Biology
Starfish reproduce by fragmentation and yeasts reproduce by budding. Both are types of asexual reproduction.

52. (KAL-uhn-KOH-ee) produces tiny buds from the tips of its leaves.
Budding
Both unicellular and multicellular organisms can reproduce by budding. Some yeast and single-celled organisms reproduce asexually by budding.
A process in which an organism develops tiny buds on its body. Each bud forms from the parents’ cells, so the bud’s genetic material is the same as the parents’
The bud grows until it forms a complete or nearly complete new organism that is genetically identical to the parent.
In some budding organisms, buds can form from any part of the body.
In other organisms, buds can be produced only by specialized cells in particular parts of the body.
A new organism produced by budding may remain attached to its parent. Most often, when a bud reaches a certain size, it breaks free of the parent and becomes a separate, independent organism.
Hydras are freshwater animals that are famous for reproducing by budding.
Kalanchoe plant
(KAL-uhn-KOH-ee) produces tiny buds from the tips of its leaves.

53. Regeneration or Fragmentation
In certain multicellular organisms, specialized cells at the site of a wound or lost limb are able to become different types of tissues.
The process of new tissue growth at these sites is called regeneration.
Although one function of regeneration is the regrowth of damaged or missing body parts, in some organisms asexual reproduction is another function of regeneration.
Regeneration can be observed in starfish. If a starfish is cut in half, each half can regenerate its missing body parts from its own cells.
The result is two complete, independent, and genetically identical starfish.
Sometimes a starfish will drop off one of its limbs. The animal will eventually form a new limb. In these cases, regeneration is considered a form of asexual reproduction.
Starfish regeneration (2:26)
The growth of plants from cuttings is also a kind of asexual reproduction through regeneration. Cells near a cut made in a plant’s stem begin to produce the missing part of the plant. Once the missing part is grown, the cutting can be planted in soil. The cutting will grow into a new, independent plant that is genetically identical to the plant from which the cutting was taken.

54. Mitosis and Cytokinesis
Section 9.2

55. Chromosomes
The genetic information that is passed on from one generation of cells to the next is carried by chromosomes.
Every cell must copy its genetic information before cell division begins.
Each daughter cell gets its own copy of that genetic information.
Cells of every organism have a specific number of chromosomes.

56. Chromosomes
Chromosomes – bundled packages of DNA that contain genetic information
Every organism has a specific number of chromosomes
Fruit flies – 4
Dog - 78
Carrots – 18
How many chromosomes do humans have? 46 (23 pairs)

57. Prokaryotic Chromosomes
Prokaryotic cells lack nuclei. Instead, their DNA molecules are found in the cytoplasm.
Most prokaryotes contain a single, circular DNA molecule, or chromosome, that contains most of the cell’s genetic information.

58. The Prokaryotic Cell Cycle
Binary fission is a form of asexual reproduction during which two genetically identical cells are produced.
DNA is replicated, cell doubles in size and splits
For example, bacteria reproduce by binary fission.
Binary Fission (1:02)

59. Eukaryotic Chromosomes
In eukaryotic cells, chromosomes are located in the nucleus, and are made up of chromatin.
Chromatin is composed of DNA and histone proteins.
DNA coils around histone proteins to form nucleosomes.
The nucleosomes interact with one another to form coils and supercoils that make up chromosomes.

60. Chromosomes Chromosomes are only visible during CELL DIVISION
Why is this?
DNA and protein molecules are spread throughout the nucleus in the form of chromatin.
Chromatin condenses during cell division.
Before division, the chromosome (DNA) is replicated
The replicated chromosome consists of 2 identical “sister” chromatids.
One chromatid goes to each new cell
Held together near the center by centromere
Sister chromatids
Exact copies of each other
Centromere
TEM 36,000

61. The Eukaryotic Cell Cycle
The eukaryotic cell cycle consists of four phases: G1, S, G2, and M.
Interphase is the time between cell divisions. It is a period of growth that consists of the G1, S, and G2 phases. The M phase is the period of cell division.
Cell Cycle and Mitosis (6:20 – stop at 2:00 min)
Eukaryotic Cell Cycle | Biology | Genetics (4:19)

62. G1 Phase: Cell Growth In the G1 phase, cells increase in size
The cell makes a variety of proteins that are needed for DNA replication.
The cells make organelles

63. G0 Phase
Not all cells are continually replicated.
Example: nerve cells, heart cells
Cells enter G0 from G1
Nonreplicating cells are found in G0 – quiescent (dormant) or senesecent (aging or deteriorating)
Do NOT copy their DNA, do NOT prepare for cell division
Cells may remain quiescent in G0 for an indeterminate period of time (when no more new cells are needed), only to re-enter G1 phase and begin dividing again under specific conditions.

64. S Phase: DNA Replication
In the S (or synthesis) phase, new DNA is synthesized when the chromosomes are replicated.
Following replication, each chromosome now consists of 2 sister chromatids.
Thus, the amount of DNA in the cell has effectively doubled.

65. G2 Phase: Preparing for Cell Division
In the G2 phase, many of the organelles and molecules required for cell division are produced.
McGraw Hill Control of Cell Cycle
McGraw Hill - How the Cell Cycle Works

66. How the Cell Cycle Works (3:00)
M Phase: Cell Division
In eukaryotes, cell division occurs in two stages: mitosis and cytokinesis.
Mitosis is the division of the cell nucleus.
Cytokinesis is the division of the cytoplasm.
How the Cell Cycle Works (3:00)
Mitosis (1:29)

67. Important Cell Structures Involved in Mitosis
Chromatid – each strand of a duplicated chromosome
Centromere – the area where each pair of chromatids is joined
Centrioles – tiny structures located in the cytoplasm of animal cells that help organize the spindle
Spindle – a fanlike microtubule structure that helps separate the chromatids

68. Cell Cycle and Mitosis (6:20 – start at 2:00 min)
Prophase
During prophase, the first phase of mitosis, the duplicated chromosome condenses and becomes visible.
The centrioles move to opposite sides of nucleus and help organize the spindle.
The spindle forms and DNA strands attach at a point called their centromere.
The nucleolus disappears and nuclear envelope breaks down.
This is the longest stage of mitosis.
Cell Cycle and Mitosis (6:20 – start at 2:00 min)

69. Metaphase
During metaphase, the second phase of mitosis, the centromeres of the duplicated chromosomes line up across the center of the cell.
The spindle fibers connect the centromere of each chromosome to the two poles of the spindle.
This is the shortest phase of mitosis.

70. Anaphase
During anaphase, the third phase of mitosis, the centromeres are pulled apart and the chromatids separate to become individual chromosomes.
The chromosomes separate into two groups near the poles of the spindle.

71. Telophase
During telophase, the fourth and final phase of mitosis, the chromosomes spread out into a tangle of chromatin.
A nuclear envelope re-forms around each cluster of chromosomes.
The spindle breaks apart, and a nucleolus becomes visible in each daughter nucleus.
Chromosomes uncoil.
Mitosis - Pearson (3:18)

72. Cytokinesis in Animal Cells
The cell membrane is drawn in (cleavage furrow)until the cytoplasm is pinched into two equal parts.
Each part contains its own nucleus and organelles.

73. Cytokinesis in Plant Cells
TEM 7,500
Cell plate forming
Wall of parent cell
Daughter nucleus
Cell wall
New cell wall
Vesicles containing cell wall material
Cell plate
Daughter cells
Plant Cells
In plants, the cell membrane is not flexible enough to draw inward because of the rigid cell wall.
A cell plate forms between the divided nuclei that develops into cell membranes.
A cell wall then forms in between the two new membranes.
McGraw Hill - Mitosis and Cytokinesis Cytokinesis in Animal and Plant Cells (3 min)

74. Telophase and Cytokinesis

75. The Stages of the Cell Cycle
Cell Cycle and Mitosis (6:20 – start at 2:00 min)

76. Mitosis Vcell Productions (6:10)
Mitosis Animation
Mitosis Vcell Productions (6:10)

77. a) metaphase c) telophase e) interphase g) cytokinesis b) anaphase
(f)
(g)
a) metaphase
c) telophase
e) interphase
g) cytokinesis
b) anaphase
d) prophase
f) anaphase

78. Video clips and Animations
Mitosis (1:29)
Eukaryotic Cell Cycle | Biology | Genetics (4:19)
Stages of Mitosis (4:30)
Mitosis Vcell Productions (6:10)
Mitosis - Pearson (3:18)
Cell Cycle and Mitosis (6:20)
Meiosis (5:27)
PBS (Mitosis vs Meiosis) Interactive

81. Cell Cycle Regulation
Section 9.3

82. Regulating the Cell Cycle
Cell growth and division are very controlled
True or False – All cells move through the cell cycle at the same rate.
The average human cell cycle is about 20 hours.
Most muscle and nerve cells do not divide once they have developed
Blood, skin and digestive tract cells divide rapidly throughout life

84. Controls of Cell Division
What happens when cells are grown in a petri dish?
Cells will grow until they come in contact with one each other (forming a thin layer covering the bottom of the dish)
What does this experiment show?
Controls of cell division can be turned on and off
What happens in our body that is similar?
The cells at the edge of an injury (cut in the skin or break in a bone) are stimulated to divide rapidly
New cells form starting the process of healing
When the healing process nears completion, the rate of cell division slows

85. Cell Cycle Regulators
Scientists have been trying to determine what regulates the cell cycle.
Biologists discovered a protein that when injected into a non-dividing cell, a mitotic spindle would form.
What is the protein called? cyclin
Why? regulates cell cycle
Cyclins regulate the timing of the cell cycle in eukaryotic cells.

86. Cell Cycle

87. Internal Regulators External Regulators Regulatory Proteins
Proteins that respond to events inside the cell
Only allow the cell cycle to proceed when certain events have occurred in the cell itself
Example: internal regulatory proteins don’t allow mitosis to start until all chromosomes are replicated; prevents a cell from entering anaphase until spindle fibers have attached to the chromosomes
External Regulators
Proteins that respond to events outside the cell.
Direct cells to speed up or slow down the cell cycle
Example: Growth Factors stimulate growth and division of cells; important in embryonic development and wound healing; preventing excessive cell growth

88. Cell Cycle Checkpoints

89. Cell Cycle Checkpoints

90. Uncontrolled Cell Growth = CANCER
Cancer cells do not respond to cycle regulators
Cells divide uncontrollably
Cancer cells form tumors (mass of cells) that can damage the surrounding tissue
Not all tumors are cancerous = benign (noncancerous)
Does not spread to surrounding healthy tissue

91. What is Cancer Fuse School (3:18)

93. Uncontrolled Cell Growth = CANCER
What are some causes of cancer?
defects in genes that regulate cell growth and division
Smoking/chewing tobacco, radiation exposure, other defective genes, viral infection
Cancer cells may break loose from tumors and spread throughout the body disrupting normal activities.
Cancer cells absorb nutrients needed by other cells, block nerve connections, prevent organs from functioning properly

94. Uncontrolled Cell Growth = CANCER
All cancers have one thing in common:
The control over the cell cycle has broken down
Some cancers will no longer respond to external growth regulators
Others fail to produce the internal regulators that ensure orderly growth
Many cancer cells have a defect in gene p53 which normally halts the cell cycle until all chromosomes have been properly replicated
damaged or defective p53 genes cause cells to lose the information needed to respond to signals that normally control their growth

95. Treatments Surgery Radiation – targeted beams of radiation
Chemotherapy – chemical compounds that kill cancer cells or slow the growth
Systemic therapy (affecting the whole body) that targets and kills rapidly dividing cells in the body, such as cancer cells.
There are normal cells in the body which are rapidly dividing as well, and chemotherapy may damage these healthy cells.
This is why chemotherapy can have side effects including hair loss, diarrhea, nausea and vomiting.