1. Essential Lecture Questions After lecture you should be able to answer…
1. What are the reasons cells undergo mitosis?
2. What are the parts of the cell cycle?
In which part does DNA duplicate?
In which part does mitosis occur?
3. What are the 4 stages of mitosis? What happens in each stage?
4. What is the end result of mitosis?

2. The Cell Cycle
The Cell Cycle-  During the cell cycle, the cell grows, replicates its DNA, and divides into two daughter cells. G1, S, G2, M
Interphase- Cell is growing and preparing for cell division
G1 phase
S phase – DNA Replication
G2 phase
Cell Division- (M phase) process of one cell forming two daughter cells.
Mitosis- Nuclear division
Cytokinesis- cytoplasm division

3. Figure The cell cycle

4. Interphase (94% of a Cell’s Life)
G1 phase
Cell increases in size
Synthesize new proteins and organelles
S phase
Chromosomes are replicated here
DNA/protein complex
G2 phase
Many organelles and molecules required for cell division are produced

5. Definition of Mitosis What is mitosis?
Mitosis is the nuclear division and cytokinesis, in eukaryotic cells, producing 2 daughter cells with the same diploid (2n) number of chromosomes (somatic cells).

6. Types of Cells Somatic Cells- regular body cells (skin, muscle, etc)
Diploid (2n)- have two kinds of each chromosome
Somatic cells undergo mitosis
Gamete (germ) Cells- sex cells (sperm and egg)
Haploid (n)- have one kind of each chromosome.
Haploid cells will fuse to form a diploid zygote
Cells undergo meiosis to form germ cells

7. Why a Somatic Cell Divides
The larger a cell grows, the more demands the cell places on its DNA and the more trouble the cell has moving enough nutrients and wastes across the cell membrane
Specific issues a cell has:
DNA “Overload”
Trouble Exchanging Material – Surface area/to volume ratio
Damage to tissues; repair
Growth of organism signals mitosis – HGF, steroids

8. Figure 12.1c The functions of cell division: Tissue renewal

9. Why a Somatic Cell Divides
DNA “Overload”
Information is stored in DNA
As a cell grows it usually does not make copies of DNA
If a cell grew too large an information crisis would occur (not enough DNA to instruct the cell as needed)

10. Why a Somatic Cell Divides
Cellular Transport needs
The larger the cell volume:
the more food, water, and oxygen needed
The more wastes produced
Less efficient transport
The bigger the cell the greater the distance and more material to get out and in; more volume, less surface area (plasma membrane)

11. Why a Somatic Cell Divides
Surface Area to Volume
Cell volume grows quicker than cell surface
At some point in time there is not enough surface area for material exchange (ex. food and waste)

12. Key to cell division is the copying and equal separation of chromosomes….
Chromatin – hazy loose DNA becomes condensed and coiled  chromosomes
Chromosome- DNA and proteins that contain genetic information
46 human chromosomes or 23 pairs
Sister Chromatids- when chromosomes are replicated and there are 2 identical parts
Centromere- part where sister chromatids are attached

13. Figure 12.3 Chromosome duplication and distribution during mitosis

14. M phase: Mitosis PMAT Prophase Metaphase Anaphase Telophase
PMAT + C = Cell Division

15. Cell Division (mitosis and cytokinesis)
Mitosis (P M A T) C
Prophase
Metaphase
Anaphase
Telophase

16. Mitosis
Prophase- 1st and longest phase of mitosis

17. Mitosis
Metaphase- 2nd stage of mitosis

18. Mitosis
Anaphase- 3rd stage of mitosis

19. Mitosis Telophase- 4th stage of mitosis
In animal cells, a cleavage furrow forms

20. Cell Division (mitosis and cytokinesis)
Cytokinesis- usually occurs at the same time as telophase of mitosis
In animal cells, a cleavage furrow forms
In plants cytoplasm is divided by a cell plate being formed

21. Cytokinesis Division of the cytoplasm itself Plants lack centrioles
Can take place in a number of ways:
*in animal cells – “draw-string” effect
*in plant cells – cell plate forms from inside out, and cell wall begins to appear

22. Figure 12.8 Cytokinesis in animal and plant cells

23. Concept Map of all events of Cell Cycle
Section 10-2
Cell Cycle
includes
M phase
(Mitosis)
Interphase
is divided into
is divided into
G1 phase
S phase
Prophase
G2 phase
Metaphase
Telophase
Anaphase
Go to Section:

24. Prokaryote vs. Eukaryote Result
Multicellular Eukaryotes – Results include growth, repair of specialized cells in a multicellular organism
Unicellular Eukaryotes and Prokaryotes – called Cell Division is called Binary Fission
What is the result?

26. Why do some human cells divide often and others not at all?

27. When cells come into contact with other cells, they stop growing…..

28. Regulating Cell Division
Internal regulators
Proteins that respond to events inside the cell
Cyclins- regulate the timing of the cell cycle in eukaryotic cells
External regulators
Closeness of neighboring cells slows growth (no contact inhibition)
Protein hormones
Ex. Growth factors stimulate growth

29. Effect of Cyclin on the cell cycle

30. Role of proto-oncogenes and oncogenes
Proto-oncogenes (unmutated oncogenes) stimulate cell division in a regulated manner. Proto-oncogenes include growth factors, growth factor receptors, and cyclins.
Oncogenes are mutated forms of these genes that result in unregulated stimulation of cell division.

31. Cancer

32. Uncontrolled Cell Growth
If growth is not controlled, then crowding and even tissue damage may result
Ex. Cancer: disorder where body’s own cells lose the ability to control growth; can crowd and even damage tissue in surrounding area – forms tumor
Benign vs. malignant tumors – benign are localized and not spreading; malignant tumors become invasive enough to impair normal function of other organs
Also, malignancies are capable of breaking off and starting up in another location -- metastasis

33. How do malignancies form?
Angiogenesis

34. Cancer Formation DNA Mutations – Carcingens, mutagens - oncogenes
Excessive hormones – genetic, environmental
Heritable mutations – mutations in cell cycle control genes (Ex: p53)
Viral infections – Can insert in DNA and disrupt control over cell cycle (HPV)
Mutated receptor proteins – bind hormones too tightly (HER2 Receptor)

35. HPV & Cervical Cancer

36. Treatment
Surgery: mastectomy (breast cancer), prostatectomy (prostate cancer) etc./can allow staging of the cancer
Radiation therapy: use of ionizing radiation that damages genetic material so much that cell can no further divide (normal cells can be affected by radiation as well but can recover)
Chemotherapy: cytotoxic drugs targeting all rapidly dividing cells by interfering with phases of the cell cycle
Immunotherapy: stimulation of own immune system to destroy cancerous cells – alpha interferon