Mitosis
Review
• A long stretch of DNA that codes for a protein is a
___________________
• Many of these put together forms a
___________________
• These are all located in the ______________ of the cell
• Each human’s normal cells have ___ chromosomes
• We call these cells ___________ cells
• Each human’s sex cells have ____ chromosomes
• We call these cells ___________ cells
Alleles
• In all of your body cells (also
called somatic cells, you have
2 copies of every gene
• 1 copy from your father, 1
copy from your mother
• The two alleles combined
code for traits and
characteristics
The Cell Cycle
• A cell has 2 main stages in its life:
1. Interphase:
• 95% of the cell’s life is spent in this phase
• Not dividing
2. Mitosis:
• The cell divides into 2 identical daughter cells
• Split into 4 stages
DNA Replication
• Remember: a normal
body cell needs to have
46 chromosomes
• This means before
mitosis can happen, the
mother cell has to
replicate (make a copy)
its DNA
• DNA replicates in S
phase (a part of
interphase)
Mitosis
• Has 4 stages:
•
•
•
•
Prophase
Metaphase
Anaphase
Telophase
Stage 1: Prophase
• Nuclear membrane disappears
• Before mitosis happens, DNA is defused throughout the
nucleus
– During prophase, DNA coil up into chromosomes and take shape
• Organelles called centrioles start to exude spindle fibres
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Stage 2: Metaphase
• The duplicated
chromosomes align
along the equator of the
cell
• The spindle fibres attach
to the centromeres of
each chromosome pair
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Stage 3: Anaphase
• Spindle fibres pull the chromosomes pairs apart towards
the two poles of the cell
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Stage 4: Telophase
• Chromosomes start to uncoil and decondense
• Cleavage furrow forms near the middle of the cell
• One cell splits into two through cytokinesis
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Identify the stages!
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