Mitosis. “The Life and Times of the Cell”. Objectives. List factors that influence when cells divide Understand & describe the ‘Cell Cycle’ Study the events of cell division (Mitosis) Compare Mitosis in plant & animal cells Cell Division Animation. Reading Assignment.
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“The Life and Times of the Cell”
List factors that influence when cells divide
Understand & describe the ‘Cell Cycle’
Study the events of cell division (Mitosis)
Compare Mitosis in plant & animal cells
Cell Division Animation
An enzyme called Helicase causes the hydrogen bonds that hold DNA together to break or ‘unzip’
Then DNA Polymerase allows free floating nucleotides to attach to the single strand of DNA
DNA is Replicated
DNA Replication..Who wants to try?
Replicated centrioles split and start moving to opposite sides of the cell forming ASTERS.
Nuclear envelop disappears
Replicated chromatin shortens, thickens and forms CHROMATID PAIRS
Centrioles have reached opposite poles of the cell
Chromatid Pairs float throughout the cytoplasm.
Shortest stage of Mitosis
Chromatid pairs align at the equator of the spindle
Chromatid pairs split
Spindle fibers contract and the single CHROMOSOMES are pulled to opposite poles
Often described as the opposite of prophase
Nuclear envelop reappears
The chromosomes unravel to become chromatin
Cleavage furrow begins to form
Cleavage furrow completes it’s indentation.
“Mother” cell splits into 2 identical “Daughter” cells in a process called CYTOKINESIS
Replicated chromatin condense into chromatid pair
Centrioles move to opposite poles
Nuclear envelope disappears
Spindle fibers start to form
Chromatid pairs line up at the equator
Chromatid pairs split
Chromosomes are pulled to opposite poles by the spindle fibers
Chromosomes de-condense into chromatin
Nuclear envelope reappears
Cytoplasm is divided into 2 cells
Some cells do not replicate their centrioles during Prophase.
They lose their ability to divide
They enter the Gap 0 stage
Neurons of the Spinal cord / Brain cells
Plants have no centrioles but still form spindle fibers
Plant cells divide from the inside out
Method of reproduction for all single celled organisms
Allows us to regenerate cells (tissue) repair cuts, bone breaks, etc
Growth – one cell to trillions