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MITOSIS and the CELL CYCLE
CELL DIVISION AND REPRODUCTION
NOTEBOOK PAGES 54/55
How do little elephants grow up to be BIG elephants?
Why and how do animals shed their skin?
Cell Division is the answer! MITOSIS Asexual cell division
that duplicates a cell exactly with ALL the genetic material in the new cell
DIPLOID CELLS ARE CREATED
MEIOSIS Cell division of sex
cells that have only HALF the regular amount of genetic information in the new cell.
HAPLOID CELLS!
The process of cell division (MITOSIS) begins
after a sperm fertilizes an egg.
GENETIC INFORMATION LOCATED IN THE NUCLEUS
CHROMOSOMES- 46 in every normal human cell, DNA- carries info about all
cells and the organism
CENTROMERE- center where the nucleus and genetic material start to divide
CENTRIOLES- poles that appear at the sides or edges of the cell during mitosis
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.
Cell that reproduce by asexual reproduction reproduce constantly.
Animated Mitosis Cyclehttp://www.cellsalive.com/mitosis.htm
• Interphase
• Prophase
• Metaphase
• Anaphase
• Telophase & Cytokinesis
I PAID MY ATTORNEY THOUSANDS(CONSTANTLY)
I- InterphasePAID- Prophase MY- Metaphase ATTORNEY- Anaphase THOUSANDS- Telophase(CONSTANTLY)- Cytokinesis
Interphase occurs before mitosis begins
resting periodCELLS ARE DIPLOID- FULL NUMBER OF
CHROMOSOMES (46)
• 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
InterphaseInterphase
Animal Cell Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
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
Prophase
Animal Cell Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Spindle fibers
Centrioles
Metaphase 2nd step in Mitosis
• Chromatids (or pairs of chromosomes) attach to the spindle fibers.
Centrioles
Spindle fibers
Metaphase
Animal Cell Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Anaphase 3rd step in Mitosis
• Chromatids (or pairs of chromosomes) separate and begin to move to opposite ends of the cell.
Centrioles
Spindle fibers
Anaphase
Animal Cell Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Telophase 4th step in Mitosis
• Two new nuclei form. • Chromosomes appear as chromatin (threads
rather than rods).• Mitosis ends.
NucleiNuclei
Chromatin
Telophase
Animal Cell Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Cytokinesisoccurs after mitosis
2 new cells have successfully
formed • Cell membrane moves inward to create two
daughter cells – each with its own nucleus with identical chromosomes.
Animal Mitosis -- Review
Interphase
Prophase
Metaphase
Anaphase
Telophase
Interphase
Plant Mitosis -- ReviewInterphase
Prophase
Metaphase
Anaphase
Telophase
Interphase
Cell Cycle
25
The Cell Cycle
26
- A review of the steps of Mitosis:
26
