Download Notes on Mitosis

Notes on Mitosis
Cell Division
What are the benefits of reproducing asexually?
It is fast.
No partner is required - think of vast oceans, or of
organisms that are not mobile. How would they be
able to reproduce?
Exact copies of parent.
What are the stages in a cell cycle?
1. Interphase - this is when a cell grows and carries
on it’s job. Late in this phase the chromosomes
are duplicated (DNA replication) in preparation
for cell division. This phase is the longest phase
and it can also be broken down into 3 subphases; G1, S and G2.
2. Mitosis - which has 4 phases
3. Cytokinesis - the division of the cytoplasm and all
organelles.
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Of these stages where would the majority of a cell’s life
be spent?
The majority of a cell’s life is spent in
INTERPHASE. This is where a cell grows and
prepares for cell division.
How many phases are there in mitosis?
There are 4 phases.
Prophase, metaphase, anaphase and
telophase.
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What happens in Prophase?
The longest phase of mitosis begins with duplicate
chromosomes called sister chromatids.
Sister chromatids are held together by a centromere.
The nuclear membrane and nucleolus disintergrate.
Centrioles form and move to opposite ends of the cell.
Spindle fibers form.
What happens in metaphase?
The sister chromatids become attached to the spindle
fibers.
This allows the chromosomes to start aligning in the
middle of the cell on what you might imagine to be the
“equator”.
I remember this phase for “M” middle.
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What happens in Anaphase?
The sister chromatids separate!
Each half of the chromosome is pulled
towards the opposite side of the cell.
This ensures that each cell will have a
complete copy of the chromosome.
I remember this for “A” apart.
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What happens in Telophase?
The chromatids are now at opposite ends.
Spindle fibers break down.
The nucleolus reappears and a new nuclear
envelope forms.
A double membrane begins to form between the 2
new nuclei.
I remember this for “T” tear apart.
What is cytokinesis?
This is the division of the cytoplasm and all the
organelles.
The end result is the formation of 2 separate
cells.
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What is the end result of mitosis?
You get TWO IDENTICAL CELLS!
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