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Learn about the process of cell division and its importance in both unicellular and multicellular organisms. Explore the steps of mitosis and meiosis, and understand the differences between these two types of cell division. Discover how mitosis produces normal body cells, while meiosis produces reproductive cells.
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Cell Division By Mr. Kauffman
Cells Review What is cell division? The Cell Cycle Interphase Mitosis 4 Steps of Mitosis Results of Mitosis Meiosis 8 Steps of Meiosis Results of Meiosis 2 Types of Cell Division Outline
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 • Usually 1 cell divides to make 2 cells • Why is cell division important to multicellular organisms? • Its how they grow • Replace cells that have died • Why is cell division important to unicellular organisms? • Its how they reproduce Cancer cell dividing E. Coli cell dividing
The Cell Cycle • Cell cycle: everything that happens from 1 cell division to the next • 2 parts 1. Interphase 2. Mitosis
Interphase • Interphase: longest part of the cell cycle • The cell prepares to divide • It grows in size • It copies its DNA
Mitosis • Mitosis: Part of the cell cycle when the cell actually divides to form 2 identical cells • Produces normal body cells • Skin and muscle cells • The cells produced are identical to each other and to the original cell
Mitosis • Mitosis has 4 steps: 1) Prophase 2) Metaphase 3) Anaphase 4) Telophase
4 Steps of Mitosis • Prophase • 1st step • Nucleus disappears • Chromosomes form in nucleus (look like X’s) • These are how the DNA is stored in our cells • Humans have 46 single chromosomes (23 pairs)
4 Steps of Mitosis • Metaphase • 2nd step • Chromosomes are lined up in the middle of the cell
4 Steps of Mitosis • Anaphase • 3rd step • Chromosomes are pulled apart • ½ of each chromosome goes to each end of the cell
4 Steps of Mitosis • Telophase • 4th step • Cytoplasm begins to pinch in at center of cell • Eventually the 1 cell splits to form 2 cells • Each new cell has its own nucleus and set of DNA
Results of Mitosis • Mitosis produces normal cells in the body • Skin and muscle cells • 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
Meiosis • Meiosis: cell division that produces reproductive cells • Reproductive cells are also called gametes • 2 basic types of gametes (reproductive cells) • Females – egg cells • Males – sperm cells
Why Meiosis is Needed • Fertilization: combining of sperm and egg cells to form a zygote • the zygote then grows and develops into a new organism • how living things reproduce sexually (combining of 2 cells)
Meiosis • Meiosis has 8 steps • Basically goes through mitosis twice • There are 2 cell divisions
Meiosis • 8 Steps of Meiosis: • Prophase 1 • Metaphase 1 • Anaphase 1 • Telophase 1 • Prophase 2 • Metaphase 2 • Anaphase 2 • Telophase 2
Results of Meiosis • Meiosis produces reproductive cells (gametes) • Sperm and egg cells • 1 cell splits to form 4 cells • The 4 new cells have ½ of the DNA that the original cell had • Haploid cells: cells with ½ of the amount of DNA of a normal cell • Diploid cells: cells with the normal amount of DNA
2 Types of Cell Division in Humans Mitosis Characteristics Meiosis Normal body cells Types of cells produced Reproductive cells 4 # of steps 8 PMAT (1 and 2) PMAT Step names 2 # of cells produced 4 46 (single) # of chromosomes in cells 23 (single) Identical Comparison to original cell ½ the DNA