Cell Division By: Mr. Kauffman

Outline Cells Review What is cell division? Why is cell division important? The cell cycle 4 Steps of mitosis Results of mitosis

Cells Review Cell: smallest part of any living thing that carries out the functions necessary to support life Unicellular organism: living thing made up of 1 cell Multicellular organism: living thing made up of many cells

What is cell division? Cell division: a way to produce more cells –1–1 cell divides to make 2 cells Why is cell division important to multicellular organisms? –I–Its how they grow –R–Replace cells that have died Why is cell division important to unicellular organisms? –I–Its how they reproduce Cancer cell dividing E. Coli cell dividing

The Cell Cycle Cell cycle: the events that take place in between cell divisions Interphase: longest part of the cell cycle –When the cell grows and prepares to divide –The cell copies its hereditary material (DNA) Each new cell will receive a copy of the hereditary material

Mitosis Mitosis: part of the cell cycle when the cell divides to form 2 identical cells –Occurs after interphase –The 2 new cells are identical to each other and identical to the original cell Mitosis has 4 steps: 1) Prophase 2) Metaphase 3) Anaphase 4) Telophase Cell Division

4 Steps of Mitosis 1.Prophase –1–1 st step –C–Chromosomes form in nucleus (look like X’s) These are how the DNA is stored in our cells –C–Centrioles and spindle fibers begin to form

4 Steps of Mitosis 2.Metaphase –2 nd step –Spindle fibers attach to the chromosomes –Chromosomes are lined up in the middle of the cell

4 Steps of Mitosis 3.Anaphase –3 rd step –Chromosomes are pulled apart –½ of each chromosome goes to each end of the cell

4 Steps of Mitosis 4.Telophase –4 th step –Cytoplasm begins to pinch in at center of cell –Eventually the 1 cell splits to form 2 cells –Chromosomes unravel

Results of Mitosis Produces normal cells in the human body –Ex: skin and muscle 1 cell splits to form 2 cells –The new cells are identical to each other –The new cells are also identical to the original cell Parent cell: name for the original cell Daughter cell: name for the cells produced

Meiosis Meiosis is cell division that produces reproductive cells –Ex: sperm and egg cells Has 2 cell divisions –Basically goes through mitosis 2 times Produces 4 cells –The 4 new cells have ½ the amount of DNA than the original cell had

2 Types of Cell Division in Humans MitosisCharacteristicsMeiosis Types of Cells Produced Final # of Cells Produced Comparison to Original Cell # of Steps Normal Body Cells Reproductive Cells (sperm end egg) 24 Identical ½ as much DNA 4 8