Mitosis Notes
Mitosis is Asexual Reproduction
• Produces genetically identical cells to the
parent cell.
•Done by somatic (body) cells in humans
Somatic cells…
• …Are diploid or 2n
•Have two of each type of chromosome
•Humans have 23 pairs or 46 total
chromosomes
Cell Cycle
• Series of events that cells go through as
they grow and divide.
4 Phases: G1, S, G2, and M
Interphase…
• …consists of G1, S, and G2
•Cell Division = M Phase = Mitosis and
Cytokinesis
•Mitosis = Prophase, Metaphase,
Anaphase, Telophase
*Interphase
• G1 = Cell growth
•S = DNA Replication
•G2 = Preparation for Mitosis
•(more organelles produced)
Prophase
• 1st Phase of Mitosis,
or M Phase
– Longest
•Chromosomes
become visible
•Condensed DNA
Prophase (cont.)
• Centrioles (in animals) move to the poles
•Aster Microtubules form around centrioles
•Spindle Microtubules Form
•Attach to the centromere and help to
move the chromosomes
Prophase (cont)
• Nuclear Membrane breaks down
•Nucleolus disappears
•Chromosomes moving towards the equator
Prophase
Asters
Centrioles
Spindle
Chromosome
Nuclear
membrane
breaking
down
Metaphase
• 2nd Phase of Mitosis
•Chromosomes line up in the middle of
the cell
Metaphase
Anaphase
• 3rd Phase of Mitosis
•Centromeres Split
•Sister chromatids now become
individual chromosomes
•Chromosomes move to the poles
Anaphase
Telophase
• 4th Phase of Mitosis
•Chromosomes begin to unwind and
become chromatin again
•Nuclear Membrane and Nucleolus reforms
•Spindles and Asters break apart
Telophase
•Mitosis or division of the nucleus is
complete
•Cytokinesis has to occur to divide the
cell or cytoplasm
•Usually occurs during Telophase
Animal Cytokinesis
• Forms a furrow
– “Pinches” from the Outside to Inside
Plant Cytokinesis
• Forms a cell plate made of cellulose
– Starts from the inside and works to the outside
Product
• 2 Genetically Identical Daughter Cells
•If not identical:
1. Cell will not function properly
2. Cell can die
Importance of Mitosis
1. Growth
2. Healing
3. Regeneration