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Non-Replicated Chromosome
Chromatin
Chromatid
Centromere
Histones
Replicated Chromosome
https://www.youtube.com/watch?v=ofjyw7ARP1c
Stages of Mitosis (first part of M phase)
Mitosis occurs in 4 steps:
1. Prophase
2. Metaphase
3. Anaphase
4. Telophase
http://www.youtube.com/watch?v=VlN7K19QB0
http://www.youtube.com/watch?v=gwcwSZIfKlM
Prophase
• DNA condenses into replicated
chromosomes
• 2 centrioles take positions on
opposite sides of the nucleus
– Centrioles control the
development and attachment
of microtubules
– Microtubules are thin hollow
tubes that are part of the
cytoskeleton.
Prophase
• A spindle begins to form
from each centriole
• Spindle: A structure that
helps move and separate
chromosomes.
• Chromosomes attach to
the spindle at the
centromere
• Nucleolus disappears
• Nuclear envelope breaks
down
Metaphase
• Chromosomes line up
across the middle of the
cell
Anaphase
• The chromosomes in the middle of the cells are split
and each chromatid is pulled in opposite directions.
• When the chomatids separate, each chromatid becomes
a chromosome.
• The chromatids move
away from each other
to opposite sides of the
cell.
Telophase
• Spindle breaks down
• The nucleus begins to reform in each end of the cell.
– Chromosomes uncoil
and relax
– Nuclear envelope
reforms around each
cluster of
chromosomes
– A nucleolus becomes
visible in each
daughter nucleus.