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Cell Division and Mitosis
The division of somatic cells
Important Vocabulary
• Mitosis: the
division of somatic
cells (all cells in
your body other
than the sperm and
egg cells).
• Cytokinesis: the
division of the
nucleus.
Chromosomes
• The genetic
information is passed
on from one
generation to the next
in chromosomes.
• Chromosomes are
made from DNA.
• Humans have 46
chromosomes this is
the diploid number.
Chromosomes
• Chromosomes are not
normally visible, but
before a cell starts to
divide the
chromosomes
condense and become
visible.
• Before cell division
starts, each
chromosome is
replicated, this
creates two identical
sister chromatids.
• One chromatid goes to
each new cell.
Chromosomes
• Chromosomes are
connected at the
center at the
centromere.
The Cell Cycle
• The cell cycle
starts with
interphase
• This is the normal
part of the cell
cycle that the cell
grows and DNA
replication takes
place.
Mitosis
• Mitosis is the actual division of the cell
broken down into four phases:
–
–
–
–
Prophase
Metaphase
Anaphase
Telophase
Prophase
• During prophase the
chromosomes become
visible
• The centrioles move to
the opposite sides of
the nucleus
• The chromosomes
attach to spindle
fibers near the
centromere
• The nuclear envelope
dissappears.
Metaphase
• During metaphase
the chromosomes
line up in the
middle of the cell.
• Microtubules
connect the
spindle fibers to
the ends of the cell
and to the
centromere of the
chromosome.
Anaphase
• The centromeres
split the sister
chromatids and
separate and
become individual
chromosomes.
• The individual
chromosomes
move to the poles.
Telophase
• The chromosome
begin to untangle.
• The nuclear
envelope reforms.
• The spindle breaks
down.
• The nucleolus of
each daughter cell
becomes visible in
the daughter cells.
Cytokinesis
• Each new daughter
cell splits its
cytoplasm.
• The new cell
membrane forms.
• In plants the cell
plate is formed and
the cell wall begins
to form.