Download 2.4 Mitosis Notes

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Section: _______________________________________________
Date: _______________________________________________
Mitosis Notes
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Cells that perform mitosis: Somatic cells (Body cells)
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Steps that occur before mitosis:
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What happens to the chromosome number before mitosis:
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What happens to the chromosomes physically before mitosis:
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Steps of mitosis:
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Details of each step:
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Cytokinesis: __________________________________________________________________________________________________
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End result of mitosis: ________________________________________________________________________________________
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Why it is so important that body cells complete mitosis: _______________________________________________
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Mitosis Notes
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Cells that perform mitosis: Somatic cells (Body cells)
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Steps that occur before mitosis:
o Interphase
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G1: Cell grows and makes new organelles
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S: DNA replicates
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G2: Cell grows and checks itself for mistakes
What happens to the chromosome number before mitosis:
Interphase
10
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What happens to the chromosomes physically before mitosis:
I I I I
I I I I
I I
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20
Steps of mitosis:
o Prophase
o Metaphase
o Anaphase
o Telophase
Interphase
X X X
X X X
X X X X
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Details of each step:
o Chromatin condenses and DNA forms chromatids (chromosomes)
o The nuclear envelope (membrane) disappears
o Spindle fibers form and connect to the chromosomes (move them around the cell)
o Meta – middle
o Spindle fibers pull the chromosomes and they are lined up in the middle of the cell.
o Spindle fibers pull apart pulling the sister chromatids apart
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1 copy goes to 1 side of the cell
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The 2nd copy goes to the other side of the cell
o Spindle fibers detach for the chromosomes and disappear
o Nuclear membranes reform around the DNA
o DNA (chromatids) unravel to the chromatin form
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Cytokinesis: Division of the cytoplasm; cytoplasm divides and cell membrane pinches off forming
2 new cells.
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End result of mitosis: 2 daughter cells that are identical to the parent cell (same number of
chromosomes and same combination of DNA as the parent cell).
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Why it is so important that body cells complete mitosis: The new cell needs to complete the same
function as the parent sell, so they need the same number of chromosomes and the same
combination of DNA to do that.