The Cell Cycle and Mitosis

Why Do Cells Divide?

Why Do Cells Divide Healing and Tissue Repair An average human looses 105 pounds of dead skin cells in their life Every second, millions of your body cells are injured or die and must be replaced Replacement of dead cells also occurs in plants

Why Do Cells Divide Growth All plants and animals begin life as a single cell Only two ways for an organism to grow: 1) single cell gets bigger; or 2) the single cell divides into more cells

Why Do Cells Divide One of the most important jobs of a cell is to exchange materials with its environment (the body or outside world) The cell needs to get food and nutrients in and waste out

Why Do Cells Divide Why Don’t Cells Just Keep Getting Bigger? Eventually a cell will reach a size where it will not be able to get enough exchange of materials to sustain cell function

Why Do Cells Divide Perpetuate Life Important for unicellular (prokaryotes) organisms like bacteria – creates 2 new organisms

Why Do Cells Divide Perpetuate Life Also essential for reproduction of multicellular organisms

The Cell Cycle The repeating cycle in the life of a cell Interphase : when a cell is preparing for cell division; this is the majority of the time Cell division : the process of 1 cell dividing into 2 cells Mitosis: division of the nucleus Cytokinesis : division of the cytoplasm

Interphase First Growth Phase (G1) Synthesis Phase (S) Period of growth for a cell Produces new proteins and organelles Synthesis Phase (S) Cell synthesizes entire copy of DNA Second Growth Phase (G2) – shortest phase Cell produces organelles and structures for cell division

Mitosis: What is it basically? DNA copies (chromosomes) are separated & sorted into two sides of the cell the cell then splits in two and part of each parent is carried to the two new cells. each ‘daughter’ cell is identical to the parent cell results in cells such as internal organs, skin, bones, blood, etc. Mitosis animation: http://www.youtube.com/watch?v=2WwIKdyBN_s&feature=related

Interphase occurs just before Mitosis begins: DNA is replicated along with organelles and other cellular components and the cell prepares for division. http://www.bioweb.uncc.edu/1110Lab/notes/notes1/lab6.htm

Before Mitosis : Interphase Animal cell Plant cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

1st step in Mitosis: Prophase (preparation phase) the DNA recoils, and the chromosomes condense the nuclear membrane disappears mitotic spindles begin to form. http://www.bioweb.uncc.edu/1110Lab/notes/notes1/lab6.htm

Mitosis Prophase Animal cell Plant cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

2nd step in Mitosis: Metaphase (organizational phase) spindle fibres attach to the chromosomes at the centromere chromosomes line up the middle of the cell http://www.bioweb.uncc.edu/1110Lab/notes/notes1/lab6.htm

Mitosis Metaphase Animal cell Plant cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

3rd step in Mitosis: Anaphase (separation phase) the chromosomes split at the centromere the ‘sister ‘chromatids are pulled by the spindle fibers to opposite poles of the cell. http://www.bioweb.uncc.edu/1110Lab/notes/notes1/lab6.htm

Mitosis Anaphase Animal cell Plant cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

4th step in Mitosis: Telophase the chromosomes, the cytoplasm and organelles divide into 2 portions.  this diagram shows the end of telophase. http://www.bioweb.uncc.edu/1110Lab/notes/notes1/lab6.htm

Mitosis Telophase Animal cell Plant cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

After Mitosis: Cytokinesis Beginning of cytokinesis in a plant: the actual splitting of the daughter cells into two separate cells is called cytokinesis occurs differently in both plant and animal cells. Beginning of cytokinesis in an animal: http://www.bioweb.uncc.edu/1110Lab/notes/notes1/lab6.htm

MITOSIS

Mitosis http://www.youtube.com/watch?v=2WwIKdyBN_s&feature=related http://www.youtube.com/watch?v=VlN7K1-9QB0 http://www.cellsalive.com/mitosis.htm http://www.sci.sdsu.edu/multimedia/mitosis/mitosis_gif2.html http://www.teachersdomain.org/resource/tdc02.sci.life.stru.dnadivide/ http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__mitosis_and_cytokinesis.html Beginning of second class

The Cell Cycle Remember iPMATc Interphase Mitosis Cytokinesis Prophase Metaphase Anaphase Telophase Cytokinesis

Homework Describe the events in the cell cycle. Explain how mitosis ensures genetic continuity. How does mitosis make the growth and repair of cells possible in an organism? Get a textbook and describe each phase of mitosis along with a picture (pg. 30-32) Also define cytokinesis and apoptosis