End Show Slide 1 of 38 Prentice Hall Biology Mr. Karns Cell Division

End Show Slide 2 of Cell Division

End Show 10-2 Cell Division Slide 3 of 38 In eukaryotes, cell division occurs in two major stages. The first stage, division of the cell nucleus, is called mitosis. The second stage, division of the cell cytoplasm, is called cytokinesis. Cell Division

End Show 10-2 Cell Division Slide 4 of 38 Chromosomes Genetic information is passed from one generation to the next on chromosomes. Before cell division, each chromosome is duplicated, or copied. This is called Replication or DNA replication. We will study this in detail in future chapters, but is copies the chromosomes exactly.

End Show 10-2 Cell Division Slide 5 of 38 Chromosomes Chromosomes appear: Once copied, the chromosomes condense and start to become visible. This happens in the first part of mitosis called prophase.

End Show 10-2 Cell Division Slide 6 of 38 Chromosomes Each chromosome consists of two identical “sister” chromatids. Each pair of chromatids is attached at an area called the centromere. Say “centromere” “chromatid”, the whole structure is a “chromosome” Sister chromatids Centromere

End Show 10-2 Cell Division Slide 7 of 38 Chromosomes When the cell divides, the chromatids separate. Each new cell gets one chromatid. Hint: one chromosome is made up of two chromatids as it has copied itself.

End Show 10-2 Cell Division Slide 8 of 38 The Cell Cycle Cell Cycle The cell cycle is the series of events that cells go through as they grow and divide. Contact inhibition and a lower surface area/volume ratio trigger cells to divide. Interphase is the period of growth that occurs between cell divisions.

End Show 10-2 Cell Division Slide 9 of 38 The Cell Cycle What are the main events of the cell cycle?

End Show 10-2 Cell Division Slide 10 of 38 The Cell Cycle During the cell cycle: a cell grows prepares for division divides to form two daughter cells, each of which begins the cycle again

End Show 10-2 Cell Division Slide 11 of 38 The Cell Cycle Cell Cycle Interphase is the period of growth that occurs between cell divisions. It

End Show 10-2 Cell Division Slide 12 of 38 The Cell Cycle The cell cycle consists of five phases: G 1 (First Gap Phase) S Phase G 2 (Second Gap Phase) M Phase mitosis Cytokinesis actual cell division into two daughter cells

End Show 10-2 Cell Division Slide 13 of 38 Events of the Cell Cycle During G 1, the cell (part of interphase) increases in size synthesizes new proteins and organelles Remember G stands for “Growth”

End Show 10-2 Cell Division Slide 14 of 38 Events of the Cell Cycle During the “S” phase, ( part of interphase) chromosomes are replicated DNA synthesis takes place Once a cell enters the S phase, it usually completes the rest of the cell cycle. Remember S for “synthesis” of new chromosomes

End Show 10-2 Cell Division Slide 15 of 38 Events of the Cell Cycle The G 2 Phase (Second Gap Phase) (part of interphase) organelles and molecules required for cell division are produced Once G 2 is complete, the cell is ready to start the M phase—Mitosis Remember G 2 for 2 nd Growth and get ready to divide

End Show 10-2 Cell Division Slide 16 of 38 Cell Cycle Events of the Cell Cycle

End Show 10-2 Cell Division Slide 17 of 38 Mitosis What are the four phases of mitosis?

End Show 10-2 Cell Division Slide 18 of 38 Mitosis Biologists divide the events of mitosis into four phases: Prophase Metaphase Anaphase Telophase Say PMAT

End Show 10-2 Cell Division Slide 19 of 38 Mitosis Look at the roots we know: add them to your derivational terms sheet Pro means before or early Meta refers to middle or in between Ana ( I don’t know! sorry) Telo means at the end of Say PMAT

End Show 10-2 Cell Division Slide 20 of 38 Mitosis

End Show 10-2 Cell Division Slide 21 of 38 Mitosis

End Show 10-2 Cell Division Slide 22 of 38 Section 10-2 Prophase Spindle forming Chromosomes (paired chromatids) Centromere Click to Continue Mitosis these are to be drawn on your drawing papers and labeled Prophase

End Show 10-2 Cell Division Slide 23 of 38 Mitosis Prophase Prophase is the first and longest phase of mitosis. The centrioles separate and take up positions on opposite sides of the nucleus. Spindle forming Centromere Chromosomes (paired chromatids)

End Show 10-2 Cell Division Slide 24 of 38 Mitosis The centrioles lie in a region called the centrosome. The centrosome helps to organize the spindle, a fanlike microtubule structure that helps separate the chromosomes. Spindle forming Centromere Chromosomes (paired chromatids)

End Show 10-2 Cell Division Slide 25 of 38 Mitosis Chromatin condenses into chromosomes. The centrioles separate and a spindle begins to form. The nuclear envelope breaks down. Spindle forming Centromere Chromosomes (paired chromatids)

End Show 10-2 Cell Division Slide 26 of 38 Centriole Spindle Mitosis Click to Continue Metaphase

End Show 10-2 Cell Division Slide 27 of 38 Mitosis Metaphase The second phase of mitosis is metaphase. The chromosomes line up across the center of the cell. Microtubules connect the centromere of each chromosome to the poles of the spindle. Centriole Spindle

End Show 10-2 Cell Division Slide 28 of 38 Individual chromosomes Anaphase Mitosis Anaphase

End Show 10-2 Cell Division Slide 29 of 38 Mitosis Anaphase Anaphase is the third phase of mitosis. The sister chromatids separate into individual chromosomes. The chromosomes continue to move until they have separated into two groups. Individual chromosomes

End Show 10-2 Cell Division Slide 30 of 38 Nuclear envelope reforming Telophase Mitosis Telophase

End Show 10-2 Cell Division Slide 31 of 38 Mitosis Telophase Telophase is the fourth and final phase of mitosis. Chromosomes gather at opposite ends of the cell and lose their distinct shape.

End Show 10-2 Cell Division Slide 32 of 38 Mitosis A new nuclear envelope forms around each cluster of chromosomes.

End Show 10-2 Cell Division Slide 33 of 38 Cytokinesis

End Show 10-2 Cell Division Slide 34 of 38 Cytokinesis During cytokinesis, the cytoplasm pinches in half. Each daughter cell has an identical set of duplicate chromosomes

End Show 10-2 Cell Division Slide 35 of 38 Cytokinesis in Plants In plants, a structure known as the cell plate forms midway between the divided nuclei. Cell wall Cell plate

End Show 10-2 Cell Division Slide 36 of 38 Cytokinesis in Plants The cell plate gradually develops into a separating membrane. A cell wall then begins to appear in the cell plate. In animal cells, there is no cell wall and a cleavage furrow begins. Cleavage means to “pinch in half” like a meat cleaver used by a butcher.

End Show - or - Continue to: Click to Launch: Slide 37 of 38 (must have QuickTake software installed on the computer you are using for this presentation) - or

End Show Slide 38 of The series of events that cells go through as they grow and divide is called a.the cell cycle. b.mitosis. c.interphase. d.cytokinesis.

End Show Slide 39 of The phase of mitosis during which the chromosomes line up across the center or equator of the cell is a.prophase. b.metaphase. c.anaphase. d.telophase.

End Show Slide 40 of Cytokinesis usually occurs a.at the same time as telophase. b.after telophase. c.during interphase. d.during anaphase

End Show Slide 41 of DNA replication takes place during the a.S phase of the cell cycle. b.G 1 phase of the cell cycle. c.G 2 phase of the cell cycle. d.M phase of the cell cycle.

End Show Slide 42 of During mitosis, “sister” chromatids begin to separate from one another during a.telophase. b.interphase. c.anaphase. d.metaphase. C

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