1. Mitosis Nestor T. Hilvano, M.D., M.P.H. (Images Copyright Discover Biology, 5 th ed., Singh-Cundy and Cain, Textbook, 2012.)

2. Learning Objectives 1. Give the meaning of following word stems. - auto, bi, centro, cyto, di, haplo, gamet, gen 2.Describe the phases (stages) and significance of cell cycle. 3.Describe the phases of mitosis. 4.Compare cytokinesis in animals and plants. 5.Discuss the functions of mitosis. 6.Explain how anchorage, cell density and growth factors control the cell. 7.Explain how cancer cells are different from healthy cells.

3. Word stem auto – self soma - body bi - two centro - center cyto - cell di - two haplo – single gamet – wife or husband gen – produce homo – like meio – less mito – thread

4. Cellular Organization of Genetic Material All the DNA in a cell constitutes the cell’s genome DNA molecules in a cell are packaged into chromosomes Somatic cells (nonreproductive cells) have two sets of chromosomes (diploid chromosomes)(2n) Gametes (reproductive cells: sperm and eggs) have 1 set (haploid) chromosomes (1n) Asexual reproduction- one parent cell (2n) divides into two daughter cells (2n); identical DNA (cloning) Sexual reproduction- two parents gametes (1n) formed into a unique new organism (2n)

5. Cell Reproduction Prokaryotes - reproduce by binary fission - one chromosome replicates equally to 2 daughter cells Eukaryotes - mitosis - chromosome duplicates to form sister chromatids, which separate during cell division to form chromosome to daughter cells. - chromosomes from both parents - DNA duplicates = 4 sets (tetrads)

7. 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 In Eukaryotes

9. 2 phases (stages) of Cell Cycle 1)Interphase – chromosomes duplicate and cells parts are made 2)Mitotic (M) phase a) mitosis, division of nucleus b) cytokinesis, the division of cytoplasm

10. Interphase 90% of the total cycle time, divided into 3 subphases: a)G1 phase (first gap) – cell grows in size b)S phase (DNAsynthesis) – chromosomes are duplicated (sister chromatids formed) c)G2 phase (second gap) – cell continue to prepare for the actual division

11. http://scienceblogs.com/transcript/2006/08/new_evidence_for_endosymbiotic.php

14. Mitosis: Stages a)Prophase – mitotic spindle forming, aster centrosomes migrate, 2 sister chromatids joined at centromere, nuclear envelope and nucleoli disperse/disappear b)Metaphase – chromosomes aligned single file on the metaphase plate c)Anaphase – chromosomes (sister chromatids) separate from the centromere, dividing to arrive at opposite ends of the cell d)Telophase – the reverse of prophase; chromatids unwind, nucleus divides into 2 genetically identical daughter nuclei

17. Cytokinesis Cytokinesis – division of cytoplasm a) animal cell – cleavage furrow b) plant cell – cell plate

19. Functions of mitosis Development Growth Replacement/ repair

20. Consequences of uncontrolled cell division Tumor a) benign tumor – lump remains at the original site b) malignant tumor – invades surrounding tissues and can metastasize - Cancers 1. carcinomas – epithelial cancers 2. sarcomas – supporting/connective tissue cancers 3. leukemias and lymphomas – blood-forming cancers.

21. Homework 1. Define – mitosis, cytokinesis, interphase, gametes, somatic cell, genome 2. Compare and contrast the stages of mitosis in prophase, prometaphase, metaphase, anaphase, and telophase. 3. Compare cytokinesis in animals and plants. 4. Distinguish between benign and malignant tumors. 5. Describe binary fission in prokaryotes (bacteria and archaea). 6. Discuss 3 factors that affect cell division.