Chapter 8-2 Cell Division

1. Chapter 8-2 Cell Division Objectives: Describe the events of binary fission. Describe each phase of the cell cycle. Summarize the phases of mitosis. Compare cytokinesis in animal cells with Cytokinesis in plant cells.

2. Cell Division in Prokaryotes Binary Fission is the division of a prokaryotic cell into two offspring cells. First the chromosome makes a copy of itself. The cell grows until It is twice the size. The cell splits into two new cells. Each new cell contains one of the identical chromosome.

3. Two identical haploid cells.

4. Cell Division in Eukaryotes Both the cytoplasm and the nucleus divide. Two kinds of cell division in eukaryotes, mitosis and meiosis. Mitosis results in new cells with genetic material that is identical to that of the original cells. Meiosis reduces the chromosome number by half in new cells. The Cell Cycle The time between cell divisions is call interphase. Duringthe G1 phase – offspring cells grow to mature size. During S phase, the cell’s DNA is copied. The G2 phase is a time the cell prepares for cell division. There is a G0 phase where cells don’t copy their DNA or prepare for cell division. Fully developed cells in the central nervous system stop dividing at maturity.

5. Mitosis is the division of the nucleus. Mitosis is divided into four phases. Prophase, metaphase, anaphase and telophase.

6. Prophase- DNA forms rod shape chromosomes. The nuclear membrane breaks down and disappears. Spindle fibers form. 2. Metaphase- The kinectochore fibers move the chromosomes to the center of the dividing cell.

7. Anaphase- The chromatids of each chromosome separate at the centromere and slowly move, centromere first, toward Opposite poles of the dividing cells.

8. Telophase- After the chromosomes reach opposite ends of the cell, the nuclear envelope forms around each set of chromosomes and a nucleolus forms in each cell. Cytokinesis: In animal cells, cytokinesis begins with a pinching inward Of the cell membrane. The area of the cell membrane that pinches in and eventually separates the dividing cell into two cells is called the cleavage furrow. In plant cells a cell plate forms.

9. Each offspring cell receives an identical copy of the original cell’s chromosomes and approximately one-half of the original cells cytoplasm and organelles.