© 2012 Pearson Education, Inc. Lecture by Edward J. Zalisko PowerPoint Lectures for Campbell Biology: Concepts & Connections, Seventh Edition Reece, Taylor, Simon, and Dickey Chapter 8 The Cellular Basis of Reproduction and Inheritance

CELL DIVISION AND REPRODUCTION © 2012 Pearson Education, Inc.

 Mitosis produces genetically identical cells for –Growth (development from an embryo into an adult) –replacement of damaged and lost cells –asexual reproduction. Cell Division Video: Sea Urchin (time lapse)

8.1 Cell division plays many important roles in the lives of organisms  Living organisms reproduce by two methods. –Asexual reproduction –produces offspring that are identical to the original cell or organism and –involves inheritance of all genes from one parent. –Sexual reproduction –produces offspring that are genetically distinct from either parent –involves inheritance of unique sets of genes from two parents. © 2012 Pearson Education, Inc.

8.2 Prokaryotes reproduce by binary fission 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 Bacteria only have a single, circular chromosome

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

 Genes are organized into linear stretches of DNA called chromosomes  Eukaryotic chromosomes are composed of chromatin consisting of –one long DNA molecule and packaging proteins (called histones)  After replication, the chromatin becomes –highly compacted and visible Chromosomes must be duplicated and equally distributed with each cell division © 2012 Pearson Education, Inc.

Figure 8.3A

Sister Chromatids are IDENTICAL!! Sister chromatids Chromosomes Centromere Chromosome duplication Sister chromatids Chromosome distribution to the daughter cells DNA molecules

Cell cycle is an ordered sequence of events from one cell division to the next © 2012 Pearson Education, Inc.  The cell cycle consists of two stages, characterized as follows: 1.Interphase: duplication of cell contents –G 1 —growth, increase in cytoplasm –S—duplication of chromosomes –G 2 —growth, preparation for division 2.Mitotic phase: division –Mitosis—division of the nucleus –Cytokinesis—division of cytoplasm

PH A SE T T MI O IC Figure 8.UN01 Genetically identical daughter cells S G1G1 G2G2 M Mitosis (division of the nucleus) Cytokinesis (division of the cytoplasm) Cytokinesis Mitosis I N T E R P H A S E Ce l l g r o w t h a n d ch r o o m s o e m d u p l i c a t i o n (DNA synthesis)

 Mitosis progresses through a series of stages: –prophase, –metaphase, –anaphase, and –telophase.  Cytokinesis often overlaps telophase. The Mitotic Phases of Cell Division Ensure Each daughter cell receives identical set of genetically material

 A mitotic spindle is, –composed of microtubules, and –produced by centrosomes, structures in the cytoplasm that –organize microtubule arrangement and –contain a pair of centrioles in animal cells. Mitotic Spindle ensure each daughter cell receives equal and identical set of chromosomes © 2012 Pearson Education, Inc. Video: Animal Mitosis

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 –The cytoplasmic contents double, –two centrosomes form, –chromosomes duplicate in the nucleus during the S phase, and –nucleoli, sites of ribosome assembly, are visible. © 2012 Pearson Education, Inc. The Mitotic Phases of Cell Division Ensure Each daughter cell receives identical set of genetically material

 Prophase –In the cytoplasm microtubules begin to emerge from centrosomes, forming the spindle. –The nuclear envelope disappears. –Chromosomes coil and become compact and –Spindle microtubules reach chromosomes - –attach at kinetochores on the centromeres of sister chromatids and –move chromosomes to the center of the cell 8.5 Cell division is a continuum of dynamic changes © 2012 Pearson Education, Inc.

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 PROPHASE

 Metaphase –The mitotic spindle is fully formed. –Chromosomes align at the cell equator (metaphase plate) –Kinetochores of sister chromatids are facing the opposite poles of the spindle. The Mitotic Phase of the Cell Cycle Divides Genetic Material © 2012 Pearson Education, Inc.

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

 Anaphase –Sister chromatids separate at the centromeres. –Daughter chromosomes are moved to opposite poles of the cell as –microtubules shorten. The Mitotic Phase Divides Genetic Material © 2012 Pearson Education, Inc.

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

 Telophase –The nuclear envelope forms around chromosomes at each pole, establishing daughter nuclei. –Chromatin uncoils and nucleoli reappear. –The spindle disappears.  During cytokinesis, the cytoplasm is divided into separate cells.  The process of cytokinesis differs in animal and plant cells. 8.5 Cell division is a continuum of dynamic changes © 2012 Pearson Education, Inc.

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

 In animal cells,  a cleavage furrow forms from a contracting ring of microfilaments (actin and myosin)  In plant cells  a cell plate forms in the middle and grows outward to divide the contents into two cells 8.6 Cytokinesis differs for plant and animal cells © 2012 Pearson Education, Inc. Animation: Cytokinesis

Cleavage furrow Contracting ring of microfilaments Daughter cells Cleavage furrow  In animal cells,  a cleavage furrow forms from a contracting ring of microfilaments (actin and myosin)

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  In plant cells  a cell plate forms in the middle and grows outward to divide the contents into two cells