CELL DIVISION AND REPRODUCTION © 2012 Pearson Education, Inc.

Cell division plays many important roles in the lives of organisms  Organisms reproduce their own kind, a key characteristic of life.  Cell division © 2012 Pearson Education, Inc.

 Cell division is used What are the purposes of cell division? © 2012 Pearson Education, Inc.

Cell division plays many important roles in the lives of organisms  Living organisms reproduce by two methods. –Asexual reproduction –Sexual reproduction © 2012 Pearson Education, Inc.

Figure 8.1A Asexual Reproduction

Figure 8.1D Sexual reproduction produces offsprings with unique combination of genes

Figure 8.1E Dividing cells in an human embryo A human kidney cell dividing

 Definition:  The chromosome of a prokaryote is. What is binary fission? © 2012 Pearson Education, Inc.

 Binary fission of a prokaryote occurs in three stages: How does binary fission occur? © 2012 Pearson Education, Inc.

Figure 8.2A_s3 Plasma membrane Cell wall Duplication of the chromosome and separation of the copies Continued elongation of the cell and movement of the copies Prokaryotic chromosome Division into two daughter cells

Figure 8.2B Prokaryotic chromosomes

THE EUKARYOTIC CELL CYCLE AND MITOSIS © 2012 Pearson Education, Inc.

 Eukaryotic cells The large, complex chromosomes of eukaryotes duplicate with each cell division © 2012 Pearson Education, Inc.

 Define chromatin  To prepare for division, the chromatin becomes –highly compact and –visible with a microscope. The large, complex chromosomes of eukaryotes duplicate with each cell division © 2012 Pearson Education, Inc.

Figure 8.3A

Figure 8.3B Sister chromatids Chromosomes Centromere Chromosome duplication Sister chromatids Chromosome distribution to the daughter cells DNA molecules

 Before a eukaryotic cell begins to divide, it duplicates all of its chromosomes, resulting in  When a cell divides, the sister chromatids The large, complex chromosomes of eukaryotes duplicate with each cell division © 2012 Pearson Education, Inc.

 Define cell cycle: The cell cycle multiplies cells © 2012 Pearson Education, Inc.

 The cell cycle consists of two stages, characterized as follows: 1.Interphase: duplication of cell contents –G 1 — –S— –G 2 — 2.Mitotic phase: division –Mitosis— –Cytokinesis— The cell cycle multiplies cells © 2012 Pearson Education, Inc.

Figure 8.4 G 1 (first gap) S (DNA synthesis) G 2 (second gap) M Cytokinesis Mitosis I N T E R P H A S E PH A SE T T MI O IC

 What are the phases of the mitosis?  Cytokinesis often overlaps telophase. Cell division is a continuum of dynamic changes © 2012 Pearson Education, Inc.

 What is the function of mitotic spindle? What are the role of centrosomes? Cell division is a continuum of dynamic changes © 2012 Pearson Education, Inc.

Figure 8.5_1 INTERPHASE MITOSIS Prophase Prometaphase Centrosome Early mitotic spindle Chromatin Fragments of the nuclear envelope Kinetochore Centrosomes (with centriole pairs) Centrioles Nuclear envelope Plasma membrane Chromosome, consisting of two sister chromatids Centromere Spindle microtubules

Interphase © 2012 Pearson Education, Inc. Prophase 1- 2-

Figure 8.5_left INTERPHASE MITOSIS ProphasePrometaphase Centrosome Early mitotic spindle Chromatin Fragments of the nuclear envelope Kinetochore Centrosomes (with centriole pairs) Centrioles Nuclear envelope Plasma membrane Chromosome, consisting of two sister chromatids Centromere Spindle microtubules

Prometaphase © 2012 Pearson Education, Inc.

Figure 8.5_5 MITOSIS Anaphase Metaphase Telophase and Cytokinesis Metaphase plate Cleavage furrow Nuclear envelope forming Daughter chromosomes Mitotic spindle

Figure 8.5_right MITOSIS Anaphase Metaphase Telophase and Cytokinesis Metaphase plate Cleavage furrow Nuclear envelope forming Daughter chromosomes Mitotic spindle

Metaphase © 2012 Pearson Education, Inc.

Anaphase © 2012 Pearson Education, Inc.

Telophase © 2012 Pearson Education, Inc.

 In animal cell Cytokinesis: division of cytoplasm. The process of cytokinesis differs in animal and plant cells. © 2012 Pearson Education, Inc.  In plant cell

Figure 8.6A Cytokinesis Cleavage furrow Contracting ring of microfilaments Daughter cells Cleavage furrow

Figure 8.6A_1 Cleavage furrow

Figure 8.6A_2 Cleavage furrow Contracting ring of microfilaments Daughter cells

Figure 8.6B Cytokinesis Cell wall of the parent cell Daughter nucleus Cell wall Plasma membrane Vesicles containing cell wall material Cell plate forming New cell wall Cell plate Daughter cells

 When the cell cycle operates normally, mitosis produces genetically identical cells for –growth, –replacement of damaged and lost cells, and –asexual reproduction. Review: Mitosis provides for growth, cell replacement, and asexual reproduction © 2012 Pearson Education, Inc. Video: Hydra Budding

Figure 8.10A

Figure 8.10B Cell replacement (in bone marrow) Asexual reproduction (of a hydra)

–start out as normal body cells, –undergo genetic mutations, –lose the ability to control the tempo of their own division, and –causing disease. Cancer cells © 2012 Pearson Education, Inc.

Figure 8.0_3