MITOSIS. How do little elephants grow up to be BIG elephants?

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MITOSIS

Transcript of MITOSIS. How do little elephants grow up to be BIG elephants?

Page 1: MITOSIS. How do little elephants grow up to be BIG elephants?

MITOSIS

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How do little elephants grow up to be BIG elephants?

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Why do animals shed their skin?

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Three reasons why cells reproduce by asexual reproduction:

1. Growth 2. Repair 3. ReplacementSkin cancer - the abnormal growth of skin cells - most often develops on skin exposed to the sun.

CellS that reproduce by asexual reproduction reproduce constantly.

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Asexual ReproductionMitosis

Mitosis is the process in which the nucleus divides to form two new nuclei.

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The process of asexual reproduction begins

after a sperm fertilizes an egg.

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Interphase occurs before mitosis begins

• Chromosomes are copied (# doubles)• Chromosomes appear as threadlike coils

(chromatin) at the start, but each chromosome and its copy(sister chromosome) change to sister chromatids at end of this phase

CELL MEMBRANENucleus

Cytoplasm

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Interphase

Animal Cell Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

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Prophase 1st step in Mitosis

• Mitosis begins (cell begins to divide)• Centrioles (or poles) appear and begin to

move to opposite end of the cell. • Spindle fibers form between the poles.

CentriolesSister chromatids

Spindle fibers

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Prophase

Animal Cell Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Spindle fibers

Centrioles

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Metaphase 2nd step in Mitosis

• Chromatids (or pairs of chromosomes) attach to the spindle fibers.

Centrioles

Spindle fibers

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Metaphase

Animal Cell Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

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Anaphase 3rd step in Mitosis

• Chromatids (or pairs of chromosomes) separate and begin to move to opposite ends of the cell.

Centrioles

Spindle fibers

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Anaphase

Animal Cell Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

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Telophase 4th step in Mitosis

• Two new nuclei form. • Chromosomes appear as chromatin

(threads rather than rods).• Mitosis ends.

NucleiNuclei

Chromatin

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Telophase

Animal Cell Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

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Cytokinesisoccurs after mitosis

• Cell membrane moves inward to create two daughter cells – each with its own nucleus with identical chromosomes.

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Animated Mitosis Cyclehttp://www.cellsalive.com/mitosis.htm

• Interphase

• Prophase

• Metaphase

• Anaphase

• Telophase & Cytokinesis

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Animal Mitosis -- Review

Interphase

                                              

              

Prophase

                                             

               

Metaphase

                                              

              

Anaphase

                                             

               

Telophase

                                              

              

Interphase

                                             

               

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Plant Mitosis -- ReviewInterphase

                                                        

    

Prophase

                                                       

     

Metaphase

                                                        

    

Anaphase

                                                       

     

Telophase

                                                        

    

Interphase

                                                       

     

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Cell Cycle

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- Cell Division

The Cell Cycle

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Mitosis Animation

http://www.cellsalive.com/mitosis.htm