1. The Cell Division in Eukaryotic Cells
Describe the events that occur during the cell cycle
Describe the structure of a chromosome

2. When you were born, you already had trillions of cells
When you were born, you already had trillions of cells. Can you believe we all started with only one?!

3. Growth of multicellular organisms occurs because cells divide!

4. This process is also used for healing, regeneration (replacing lost or dead cells) and asexual reproduction.

5. The Cell Cycle describes the events that occur from one cell division to the next.

6. The Cell Cycle consists of Interphase and Cell Division.

7. Interphase is divided into the G1, S and G2 phases
Interphase is divided into the G1, S and G2 phases. It makes up about 90% of the cell cycle
Interphase G1 S G2

8. During Interphase, DNA is wrapped around spools of protein to form chromatin.

9. Cell Cycle
Interphase
G1 phase
S phase
G2 phase
Cell Division
Mitosis
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis

10. n t e I r p h a s G1 Phase S Phase G2 Phase Cell Division
Cell growth, protein synthesis, cell respiration s I n t e r p h a
Cell Division
S Phase
DNA Replication (When the DNA duplicates)
G2 Phase
Prepare for division, protein synthesis

11. Summarize Purpose for Cell Division
What types of activities occur during interphase? What happens in each phase?
Why would an unicellular organism need to make more cells?
Why would a multicellular organism need to make more cells?

12. Before a cell can divide, it needs to make a copy of its DNA. Why
Before a cell can divide, it needs to make a copy of its DNA. Why? When in the cell cycle does this happen?

13. How are chromatin, chromosomes
During Cell Division, chromatin coils even further to condense into chromosomes
How are chromatin, chromosomes
and DNA related?

15. A chromosome consists of two identical sister chromatids attached at the centromere.
Become separated into
daughter cells
during cell division

16. Each species has a characteristic number of chromosomes in each cell.
TABLE 8-1
Chromosome Numbers of
Various Species
Organism
Number of Chromosomes
Adder’s tongue fern
1,262
Carrot 18
Cat 32
Chimpanzee 48
Dog 78
Orangutan
Earthworm 36
Fruit fly 8
Garden pea 20
Gorilla
Horse 64
Human 46
Lettuce
Sand dollar 52
Each species has a characteristic number of chromosomes in each cell.

17. Human and animal chromosomes are categorized as either autosomes or sex chromosomes
Karyotype
(identification) :
Homologous
Chromosomes
(2 matching pairs from
Your mom and dad)
Diploid (2n)
(2 of each chromosome
in each cell)
Somatic Cells
(cells that for, skin, muscle, nerves, bones cells, etc)
The picture on the right is a human karyotype. A karyotype is made by lysing cells in metaphase. At this point in the cell cycle, the chromosomes have been duplicated (S-phase) and condensed. A photograph of all the chromosomes is taken, and then the chromosome pictures are cut out and sorted in pairs from largest to smallest.
You know that each cell in your body has a full set of 46 chromosomes. Half of these came from your mother and half came from your father. Together, they make up your genome. Genetics (the last unit) allows us to examine the genes on each chromosome to determine your phenotype.
Matching chromosome pairs from your mother and father are called homologous chromosomes. These chromosomes have the same genes (though they may be different alleles), are of similar length, have centromeres in the same location, and have a similar banding pattern when stained. The first 22 pairs are called autosomes and the last set are the sex chromosomes since they determine the sex of the individual.
These are the chromosomes you will find in every cell of your body,
Somatic cells are body cells. These are your skin, muscle, nerve, bone cells, etc. Every somatic cell should have its very own set of 46 chromosomes. These cells are diploid because there are two of each chromosome in each cell. You make more somatic cells through mitosis when you need to grow or heal.

18. Human and animal reproductive cells have half the genetic information as somatic cells
Haploid (n)
(unpaired Chromosome)
Germ Cells
(cells that make gametes)
Gametes (sperm or
egg cells)

19. Summarize Chromosomes
Draw a set of homologous chromosomes
Draw & label a rectangle around one chromosome
Draw & label an oval around one sister chromatid
Draw a line and label the centromere
Explain why the resulting daughter cells are identical by the end of cell division

20. Examine the Karyotype:
Is it from a male or female?
Is it from a haploid or diploid cell?
What is its haploid number?
How do you know it is NOT from a human? What organism could this be from?

21. Cell Division is divided into Mitosis and Cytokinesis

22. Mitosis describes the division of the nucleus and its contents.

23. n t e I r p h a s G1 Phase Cell Division S Phase Mitosis G2 Phase
Cell growth, protein synthesis, cell respiration
cytokinesis s I n t e r p h a
telophase
Cell Division
anaphase
metaphase
S Phase
DNA Replication (When the DNA duplicates)
Mitosis
prophase
G2 Phase
Prepare for division, protein synthesis

24. Interphase: G1, S, G2 Nuclear envelope is intact Centrioles duplicate
Chromatin replicated
Spindle fibers not yet formed
Label centrioles, nuclear envelope, chromatin
Spindle fibers: network of microtubules that help to separate chromosomes during cell division

25. The Beginning of Cell Division: Prophase
Nuclear envelope breaks apart
Centrioles move to opposite ends
Chromatin condenses to form chromosomes
Spindle fibers form

26. Metaphase Nuclear envelope completely apart
Centrioles are at the “poles”
Chromosomes line up in the middle (along “equator”)
Spindles complete attachment to the centromeres of each chromosome

27. Anaphase Nuclear envelope still apart Centrioles still at the “poles”
Sister chromatids are being separated, pulled toward the poles
Some spindles shorten to pull apart sister chromatids, other spindles elongate to stretch the cell

28. Telophase Nuclear envelope reforms around divided chromosomes
One set of centrioles in each new cell
Chromosomes relax, become chromatin again
Spindles break apart

29. Cytokinesis divides the cytoplasm and all organelles of the cell
Cytokinesis divides the cytoplasm and all organelles of the cell. The result is two identical daughter cells. (This step overlaps with anaphase and telophase)

30. Summarize Mitosis
Compare the events that occur in prophase and telophase. What do you notice?
Compare cytokinesis in animal cells and plant cells.
What would happen if one of the sister chromatids did not separate during anaphase?
Which phases of mitosis does cytokinesis overlap?

31. Regenerative medicine and cancer research rely on understanding Cell Cycle Regulation.
Soldier Matthew Braddock

32. n t e I r p h a s G1 Checkpoint G1 Phase M Checkpoint Cell Division
Sufficient growth?
GF signal?
G1 Phase
Cell growth, protein synthesis, cell respiration
cytokinesis s I n t e r p h a
M Checkpoint
Spindles attached?
Chromosomes lined up?
telophase
Cell Division
anaphase
metaphase
S Phase
DNA Replication (When the DNA duplicates)
Mitosis
prophase
G2 Checkpoint
DNA replication?
Sufficient growth?
DNA Damage?
G2 Phase
Prepare for division, protein synthesis

33. Anchorage-dependence
Cells will divide if “anchored” to a solid surface and stop dividing when crowded.
Cancer cells rebel!
Anchorage-dependence
Density-dependent
inhibition

34. Growth Factors may stimulate further cell division
some cancer cells make their own GF

35. Cancer Treatments disrupt the cell cycle
Chemotherapy: uses drugs to kill cancer cells.
Some halt DNA replication
Some interrupt spindle attachment
Radiation therapy: uses ionizing radiation to kill cancer cells.
Further damages cancer cell DNA

36. 4. Telophase / Cytokinesis: Draw and Describe
The Cell Cycle In a paragraph, describe the 3 reasons cells divide. Describe the characteristics of the resulting daughter cells.
4. Telophase / Cytokinesis: Draw and Describe
3. Anaphase:
2. Metaphase:
1. Prophase:
Interphase
How do cells regulate the cycle? What is supposed to happen when cells become damaged? How are cancer cells different? What can form as a result? What is the difference between a benign tumor and a malignant tumor?

37. Where can you find cells actively dividing?

38. Can you find a cell in each phase of the cell cycle?

39. Can you find a cell in each phase of the cell cycle?