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This program aims to help learners understand mitosis by defining the term and describing the stages of mitosis. It also teaches how to identify cells in different stages of the cell cycle using a microscope. The program emphasizes the importance of mitosis for growth, development, and maintenance of cells.
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Objectives When you complete this program you should be able to: 1. Define the term Mitosis. 2. List and describe the stages of mitosis. 3. Identify cells in various stages of the cell cycle using a microscope.
Why is Mitosis Necessary? • The parent cell is too fat (too much volume) compared to its skin (surface area) • Wastes do not exit quickly • Nutrients do not enter quickly • Growth and development • Maintenance and repair
Cell Cycle • Cell Cycle can be defined as the life span of the cell. • The cell cycle consists of… • Interphase • Mitosis • Cytokinesis • Remember IPMAT!
Interphase • Organelles are multiplied • It madly copies its DNA in this phase in preparation for the inevitable cell division • Proteins necessary for metabolism multiply
Prophase • Chromatin condenses to produce double-stranded chromosomes • Centrioles (animal cell) or centrosomes (plant cell) go to opposing POLES or ends of the cell • Nuclear membrane begins to dissolve • Centrioles start casting out MITOTIC SPINDLE or NET
Metaphase – think “M” for MIddle • Chromosomes line up in the middle of the cell (equator/metaphase plate) attached to the spindle fibres at the centromere • Chromosomes are double-stranded here • Anaphase will not start until chromosomes are correctly lined up
ANAPHASE • Chromatids are separated and move to the poles of cell • Spindle fibres hauled in by the centrioles • Equal distribution of DNA is the objective
Telophase • Chromosomes reach the poles • Furrow appears between cells about to divide in animal cells - cell plate grows in the middle of plant cells to separate the two daughter cells • Cytoplasm and mitochondria are equally distributed to the daughter cells • Nucleus reappears • Chromosomes revert to chromatin
Interphase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Prophase Plant Cell Animal Cell Spindle fibers Centrioles Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Metaphase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Anaphase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Telophase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
IPMAT – in the order of the letters (from bottom right to top left)
Summary • The cell cycle is the life span of the cell. • Interphase is the first step in the cell cycle. Normal cell growth and DNA replication occur during interphase. • Prophase is the beginning of mitosis. The replicated chromosomes become visible in this phase. The nuclear membrane disappears • Metaphase follows prophase and is the stage in which the lining up of sister chromatids occurs at the metaphase plate.
Summary Cont. • Anaphase is the stage of mitosis in which the chromosomes begin moving to the poles of the cell. • Telophase marks the end of the mitotic process and the nucleus reappears • The two new daughter cells will now enter Interphase and begin the cell cycle over again.
Terms you must know! • Chromatin • Chromosome • Chromatid • Centromere • DNA • Interphase • Prophase • Metaphase • Anaphase • Telophase • Cytokinesis • G1 • S • G2 • Centrosome • Centriole • Spindle fibres • Cleavage furrow • Cell plate • Daughter cell
