Download MITOSIS NOTES

MITOSIS NOTES
A. How does a cell divide / reproduce? (It’s asexual, you know)
1. First, the nucleus divides. This is called MITOSIS
a. Remember the 5 steps as IPMAT
2. Second, the cytoplasm (and all the organelles) divides. This is called CYTOKINESIS
a. Most include this in the last phase (telophase), but your book considers it a
separate phase
B. What are the 5 steps of mitosis and what happens in each step?
1. INTERPHASE
a. Called the “resting” phase. The chromosomes (chromoatin) are duplicating and
making copies of themselves. You CANNOT see this happening with a
microscope.
2. PROPHASE
a. The chromosomes become thicker (chromatids) and you can see them in a
microscope. The nuclear membrane begins to disappear. Centrioles start to move
to opposite ends of the cell.
3. METAPHASE
a. The choromosomes line up in the middle of the cell. Spindle fibers attach to the
centromere.
4. ANAPHASE
a. The chromosomes pull apart and move to opposite sides of the cell. The spindle
fibers pull the chromosomes.
5. TELOPHASE
a. The nuclear membrane reappears and the chromosomes begin to disappear
(back to chromatin). The cell divides into 2 daughter cells (CYTOKINESIS).
(1. INTERPHASE…cell goes right back into interphase, growing and duplicating
everything but the chromosomes…)
VOCABULARY YOU HAVE TO KEEP STRAIGHT
CENTROSOME – Two centrioles together. Called this during interphase
CENTRIOLES – Two small rod shaped structures, only in animal cells. Play a role in cell division.
CHROMATIN – When chromosomes appear as thin, threadlike coils
CHROMATID – When chromosomes shorten and thicken, and become dark and visible
CENTROMERE – A button like structure that holds the two sister chromatids together
SPINDLE FIBERS (OR SPINDLE) – Thin rope like structures that attach to the centromere
CHROMOSOME – Two chromatids attached by a centromere