Download Mitosis & the Cell Cycle

Mitosis & the Cell
Cycle
Fall 2009
Cell Growth & Development
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Are cells of organisms the same size? Do your
cells get bigger as you grow, or do you just
produce more cells?
When talking about Cell Size…… Smaller is
Better!
The larger a cell becomes, the more demands
the cell places on its DNA, and the harder it is
to supply with nutrients.
Cell Division
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Before a cell becomes to large, a growing cell
will divide.
Cell division is the process by which a Single cell
divides into 2 Daughter cells.
Cell Division = the series of events that cells go
through as they grow and divide.
Chromosomes
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Chromosomes= are
composed of DNAWhich carries the cell’s
coded genetic
information.
Humans have 46
chromosomes(23 pairs).
The chromosomes
consist of two identical
sister chromatids.
Two Major Types of Cell Division
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Mitosis- Somatic cells
(Body Cells)
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Diploid 2N
Meiosis- Sex cells/
Gametes
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Haploid 1N
Mitosis
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Mitosis is the process by which the genetic
information is replicated and distributed to
daughter cells.
2 diploid(2N) daughter cells are produced from
1 diploid (2N) parent cell.
The Daughter cells are genetically identical to
the parent cell.
There are 4 major stages to mitosis, PMAT.
Mitosis does NOT include interphase.
Interphase
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Interphase= The cell spends most of its life
here; not part of the actual reproduction. NOT
PART OF MITOSIS.
Cell grows and replicates its DNA and centrioles.
 Nuclear membrane is visible
 Nucleus, Nucleolus, and chromatin can be seen.
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Interphase
Prophase
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Prophase: first phase of
Mitosis
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Nuclear membrane breaks
down
Chromosomes become
visible
 Centrioles separate
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Spindle forms
Metaphase
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Metaphase: Second part
of Mitosis
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Chromosomes attach to
spindle
Chromosomes line up
across the center of the
cell
Anaphase
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Anaphase: Third step in
Mitosis
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The sister chromatids
separate into two
groups near the poles of
the spindles. The
chromatids are now called
chromosomes.
Telophase
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Telophase: Fourth stage
of Mitosis
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Chromosomes gather at
opposite ends of the cell
The nuclear membrane
begins to form and
enclose the chromosomes
Cell membrane begins
to move inwards
Cytokinesis
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Cytokinesis: Final stage in
cellular division
Not Mitosis
Works with telophase
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The cytoplasm divides
completely in half.
2 daughter cells with
identical genetic
information are produced.
Cancer: Loss of Cell Control
All cancer is due to genetic mutation
Most mutations occur during an individual’s lifetime and are not
inherited (although some people have inherited a genetic
predisposition for a higher likelihood that mutations will occur)
The signals that turn on the cell cycle remain on and the signals
that block excessive division remain off. Division does not stop!
Cancer cells, if given a continual supply of
nutrients, are immortal.
A mass of abnormal cells called a tumor forms
A malignant tumor – cancer cells remain at the
original site
Metastasis – cancer cells have spread
Treatment
1. High-energy radiation that damages DNA in cancer
cells
Cancer cells have lost the ability to repair damage!
2. Chemotheraphy – toxins that interfere with cell
division are administered