Download Mitosis PPT

Mitosis
Division of regular (somatic) cells
Mitosis
• First you duplicate DNA
• Why?
– You have 2 pairs of 23
chromosomes
– If cell splits, you will only
have 1 pair
– Duplicate DNA, cell splits,
still have 2 pair
Sex chromosomes- X and Y: XX is female in humans, XY is male
Interphase
• Prior & After Mitosis
• G1 period
– 90% of cell life spent here
– Cell goes about it’s business
• S period
– DNA is duplicated
• G2 period
– Cell prepares to divide
• Cannot see DNA- uncoiled as chromatin
1. Prophase
• DNA becomes visible
as chromosomes
• Nuclear membrane
dissolves
• Centrioles migrate to
opposite poles
• Spindle fibers form
Easy to remember- Prophase- proceeding into mitosis
2. Metaphase
• Spindle fibers attach
to centromeres
• Chromosomes line up
at midline of the cell
Pole
Spindle Equator
Pole
Easy to remember- metaphase, DNA at middle
3. Anaphase
• Spindle fibers pull
apart centromeres
• One chromatid goes
to each centriole (they
look like V’s)
Easy to remember- anaphase, apart they go
4. Telophase
• Chromatids reach
centrioles
• Mitosis ends when new
nuclear membranes form
• Some evidence of cell
dividing
Easy to remember- telophase, terminal phase
Last part- Cytoplasmic division
• Technically not in mitosis
– Animal cell- pinching of cell
membrane- cleavage
– Plant cell- formation of new cell
wall- cell plate
– DNA becomes non-visible,
back to chromatin
• Daughter cells enter G1
period of interphase