GENETICS

Mitosis and the Cell Cycle

Cell reproduction

How do little elephants grow up to be BIG elephants?

Why do animals shed their skin?

Three reasons why cells reproduce by asexual reproduction:

1. Growth 2. Repair 3. Replacement

Skin cancer - the abnormal growth of skin cells - most often develops on skin exposed to the sun.

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

As you can see Mitosis is a continuous cycle and does not stop at each phase like shown in the picture.

The Cell CycleThe sequence of growth and

division of a cell.95% of cell cycle

in interphase5% of cell cycle

in mitosis

Interphase

Growth Stage 1 (G1) – metabolic activity of the cell

Synthesis Stage (S) – metabolic activity of the cell, replication of DNA

Growth Stage 2 (G2) – metabolic activity of the cell, prepare for division

InterphaseInterphase

Animal Cell Plant Cell

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

MITOSIS

There are

four phases

of mitosis.

PROPHASE METAPHASE ANAPHASE TELOPHASE

Prophase

Nuclear membrane fades Chromosomes condense – can see

sister chromatids

and centromere Spindle fibers form Centrioles start to move

to opposite poles

Prophase

Animal Cell Plant Cell

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

Spindle fibers

No Centriolesmicrotubules

Metaphase

Chromosomes line up along the equator (middle) of the cell

Each chromatid is attached to spindle with centromere

Metaphase

Animal Cell Plant Cell

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

Anaphase

Centromeres divideSister chromatids are pulled

apart to opposite poles of the cell

Each chromatid is now a separate chromosome

Anaphase

Animal Cell Plant Cell

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

Telophase

Spindle fibers dissolveChromosomes reach the

opposite poles and begin to uncoil (lengthen)

Nuclear envelopes (2) reform

Telophase

Animal Cell Plant Cell

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

Cytokinesis

Cytoplasm dividesTwo new daughter cells are

now separate

Animal Mitosis -- Review

Interphase

                                              

              

Prophase

                                             

               

Metaphase

                                              

              

Anaphase

                                             

               

Telophase

                                              

              

Interphase

                                             

               

Plant Mitosis -- ReviewInterphase

                                                

            

Prophase

                                               

             

Metaphase

                                                

            

Anaphase

                                               

             

Telophase

                                                

            

Interphase