1. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings PowerPoint ® Lecture Presentations for Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp Chapter 5 The Cell Cycle & Mitosis Control of the Cell Cycle Uncontrolled Cell Growth & Cancer http://highered.mcgraw- hill.com/sites/0072495855/student_view0/chapter2/animation__how_the_cell_cycle_works.html

2. Review: Surface Area to Volume Ratio Organisms must exchange matter with the environment to grow, reproduce and maintain organization. The cellular surface-to-volume ratio affects a biological system’s ability to obtain resources and eliminate waste products. – As cells increase in volume, the relative surface area decreases and demand for material resources increases; – Large organisms require more cellular structures to adequately exchange materials and energy with the environment; – These limitations restrict cell size – the surface area of the plasma membrane must be large enough to adequately exchange materials; – Smaller cells have a more favorable surface-to-volume ratio for exchange of materials with the environment. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

3. In unicellular organisms, division of one cell reproduces the entire organism Multicellular organisms depend on cell division for: – Development from a fertilized cell – Growth – Repair Cell division is an integral part of the cell cycle, the life of a cell from formation to its own division Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Overview: The Key Roles of Cell Division

4. Fig. 12-2 100 µm200 µm 20 µm (a) Reproduction (b) Growth and development (c) Tissue renewal

5. Cell Division Most cell division results in daughter cells with identical genetic information, DNA MITOSIS A special type of division produces nonidentical daughter cells (gametes, or sperm and egg cells) MEIOSIS Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

6. Cellular Organization of the Genetic Material All the DNA in a cell constitutes the cell’s genome A genome can consist of a single DNA molecule (common in prokaryotic cells) or a number of DNA molecules (common in eukaryotic cells) DNA molecules in a cell are packaged into chromosomes Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

7. Every eukaryotic species has a characteristic number of chromosomes in each cell nucleus Somatic cells (nonreproductive cells) have two sets of chromosomes Gametes (reproductive cells: sperm and eggs) have half as many chromosomes as somatic cells Eukaryotic chromosomes consist of chromatin, a complex of DNA and protein that condenses during cell division Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cellular Organization of the Genetic Material

8. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cellular Organization of the Genetic Material

9. Fig. 12-4 0.5 µmChromosomes Chromosome duplication (including DNA synthesis) Chromo- some arm Centromere Sister chromatids DNA molecules Separation of sister chromatids Centromere Sister chromatids

10. Eukaryotic cell division consists of: – Mitosis, the division of the nucleus – Cytokinesis, the division of the cytoplasm – Alternating with interphase in the cell cycle, mitosis followed by cytokinesis provides a mechanism in which each daughter cell receives an identical and a complete complement of chromosomes. – Mitosis ensures fidelity in the transmission of heritable information, and production of identical progeny allows organisms to grow, replace cells, and reproduce asexually. Sexual reproduction, however, involves the recombination of heritable information from both parents through fusion of gametes during fertilization. – Gametes are produced by a variation of cell division called meiosis. – Meiosis yields nonidentical daughter cells that have only one set of chromosomes, half as many as the parent cell. – Meiosis followed by fertilization provides a spectrum of possible phenotypes in offspring and on which natural selection operates. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Mitosis v. Meiosis

11. Phases of the Cell Cycle The cell cycle is a complex set of stages that is highly regulated with checkpoints, which determine the ultimate fate of the cell. The cell cycle consists of – Interphase (cell growth, synthesis of DNA and preparation for division/mitosis) – Mitotic (M) phase (mitosis and cytokinesis) Mitosis alternates with interphase in the cell cycle to pass a complete genome from the parent cell to daughter cells. http://highered.mcgraw- hill.com/sites/0072495855/student_view0/chapter2/animation__ how_the_cell_cycle_works.htmlhttp://highered.mcgraw- hill.com/sites/0072495855/student_view0/chapter2/animation__ how_the_cell_cycle_works.html Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

12. Events of the Cell Cycle Nuclear division (M phase) cell divides

13. Interphase (period of rest and preparation) is divided into 3 phases: 1.G 1 – cell growth 2.S – DNA replication 3.G 2 – preparation for Mitosis *During Interphase, chromosomes are in their “uncondensed” form and are called chromatin. Mitosis (division of the nucleus) occurs in 4 phases: 1.P = prophase – chromatin condenses into chromosomes, the centrioles separate & nuclear membrane breaks down 2.M = metaphase – chromosomes line up across center of cell and each chromosome is connected to a spindle fiber at its centromere 3.A = anaphase – sister chromatids separate into individual chromosomes and are pulled apart 4.T = telophase – chromosomes gather at opposite ends of the cell and 2 new nuclear membranes form around them *During mitosis, chromosomes are in their “uncondensed” form and are called chromatin. Cytokinesis – division of cytoplasm – well underway by late telophase

14. Fig. 12-6 G 2 of Interphase Centrosomes (with centriole pairs) Chromatin (duplicated) Nucleolus Nuclear envelope Plasma membrane Early mitotic spindle Aster Centromere Chromosome, consisting of two sister chromatids Prophase Prometaphase Fragments of nuclear envelope Nonkinetochore microtubules Kinetochore microtubule Metaphase plate Spindle Centrosome at one spindle pole Anaphase Daughter chromosomes Telophase and Cytokinesis Cleavage furrow Nucleolus forming Nuclear envelope forming

15. Mitosis passes a complete genome from the parent cell to daughter cells. – Mitosis occurs after DNA replication during interphase/S phase. – Mitosis followed by cytokinesis produces two genetically identical daughter cells. – Mitosis plays a role in growth, repair, and asexual reproduction. – Mitosis is a continuous process with observable structural features along the mitotic process (replication, alignment, separation). – Mitosis alternates with interphase in the cell cycle. – The entire cell cycle is directed by internal controls or checkpoints. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Review: The Cell Cycle

16. Many of the events of mitosis depend on the mitotic spindle, which begins to form in the cytoplasm during prophase. The mitotic spindle consists of fibers made of microtubules and associated proteins. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Mitotic Spindle: A Closer Look

17. Fig. 12-7 Microtubules Chromosomes Sister chromatids Aster Metaphase plate Centrosome Kineto- chores Kinetochore microtubules Overlapping nonkinetochore microtubules Centrosome 1 µm 0.5 µm

18. Fig. 12-9: Cytokinesis – A Closer Look Cleavage furrow 100 µm Contractile ring of microfilaments Daughter cells (a) Cleavage of an animal cell (SEM)(b) Cell plate formation in a plant cell (TEM) Vesicles forming cell plate Wall of parent cell Cell plate Daughter cells New cell wall 1 µm

19. Mitosis in Animal Cell

20. Chromatin condensing Metaphase AnaphaseTelophase Prometaphase Nucleus Prophase 1 2 3 5 4 Nucleolus Chromosomes Cell plate 10 µm Mitosis in Plant Cell

21. Binary Fission Prokaryotes (bacteria and archaea) reproduce by a type of cell division called binary fission In binary fission, the chromosome replicates (beginning at the origin of replication), and the two daughter chromosomes actively move apart Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

22. Concept 12.3: Control of the Cell Cycle How do cells know when to divide? Cell division in eukaryotes is highly complex. Some mechanisms of cell cycle control include: – Presence of proteins called cyclins (internal regulators and external regulators): Internal Regulators: respond to events inside the cell – hold cell in interphase until all chromosomes are copied. External Regulators: respond to events outside the cell and direct cells to speed up or slow down the cell cycle. – Closeness of neighboring cells: Density-dependence inhibition causes cells to stop dividing when they come in close contact with each other. Anchorage dependence allows cells to divide only when anchored to a substrate. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

23. Cell Cycle Checkpoints http://highered.mcgraw- hill.com/sites/0072495855/student_view0/chapter2/animation__control_of_the_cell_cycle.html http://highered.mcgraw- hill.com/sites/0072495855/student_view0/chapter2/animation__control_of_the_cell_cycle.html Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings At each of these checkpoints, the cell checks that it has completed all of the tasks needed and is ready to proceed to the next step in its cycle. THESE CELL CYCLE CHECKPOINTS FUNCTION TO ENSURE THAT COMPLETE GENOMES ARE TRANSMITTED TO DAUGHTER CELLS!

24. KINASES: The Protein Regulators of the Cell Cycle Cell Division is tightly controlled by complexes made of several specific proteins. – These complexes contain enzymes called cyclin-dependent kinases (CDKs), which turn on or off the various processes that take place in cell division. – CDK partners with a family of proteins called cyclins. – One such complex formed by the fusion of CDK and cyclin is mitosis-promoting factor (MPF), sometimes called maturation- promoting factor, which contains cyclin A or B and cyclin- dependent kinases (CDK). – CDK is activated when it is bound to cyclin (thus producing MPF), interacting with various other proteins that, in this case, allow the cell to proceed from G 2 to mitosis. – The levels of cyclin change during the cell cycle, shutting on and off the mitotic phases. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

25. MPF and Cell Cycle Control at G 2 Checkpoint http://www.sinauer.com/cooper5e/animation1604.html http://www.sinauer.com/cooper5e/animation1604.html Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

26. Growth Factors and Cell Cycle Control EXTERNAL factors, both chemical and physical, can influence cell division. Even when all other conditions are favorable, most mammalian cells divide only in the presence of specific growth factors. Growth factors are proteins that are released by certain cells that stimulate other cells to divide. – These are local regulators – they travel short distances influence only cells in close vicinity. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

27. PDGF and Cell Cycle Control Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

28. Contact cell cycle control mechanisms include density-dependent inhibition and anchorage dependence. – In density-dependent inhibition, crowded cells stop dividing. – Anchorage dependence is a phenomenon in which cells must be attached to a substratum (i.e. extracellular matrix of a tissue) in order to divide. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Contact Cell Cycle Control

29. Fig. 12-19 Anchorage dependence Density-dependent inhibition (a) Normal mammalian cells (b) Cancer cells 25 µm

30. Loss of Cell Cycle Controls in Cancer Cells The cell cycle is regulated very precisely. Mutations in cell cycle genes that interfere with proper cell cycle control are found very often in cancer cells. Cancer cells do not respond normally to the body’s control: – They exhibit neither density-dependent inhibition nor anchorage dependence. – They may not need growth factors to grow and divide. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

31. A normal cell is converted to a cancerous cell by a process called transformation Cancer cells form tumors, masses of abnormal cells within otherwise normal tissue If abnormal cells remain at the original site, the lump is called a benign tumor Malignant tumors invade surrounding tissues and can metastasize, exporting cancer cells to other parts of the body, where they may form secondary tumors Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cancer Cells and the Formation of Tumors

32. Fig. 12-20 http://www.youtube.com/watch?v=IeUANxFVXKc Tumor A tumor grows from a single cancer cell. Glandular tissue Lymph vessel Blood vessel Metastatic tumor Cancer cell Cancer cells invade neigh- boring tissue. Cancer cells spread to other parts of the body. Cancer cells may survive and establish a new tumor in another part of the body. 1 2 3 4