Essential Lecture Questions After lecture you should be able to answer…

1. Essential Lecture QuestionsAfter 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 12.4 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: MitosisPMAT • 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. M phase (Mitosis) Interphase G1 phase S phase G2 phase Prophase Metaphase Anaphase Telophase Concept Map of all events of Cell Cycle Section 10-2 Cell Cycle includes is divided into is divided into 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?

25. http://www.bozemanscience.com/mitosis

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