Transcript Cell Division Mitosis

Cell Division
Mitosis
Overview of Mitosis
1 Cell (mother cell)
divides into 2 Cells
(daughter cells)
 Each new cell is an
exact copy of the
mother cell
Importance of Mitosis
 Growth – adding new
cells
 Replacement –
replacing dead cells
 Repair – Replacing
cells that are
damaged or injured
Structures - Nucleus
 The Nucleus is the
control center of the
cell
Chromatin is the
threadlike structures
in the nucleus
 Chromatin is made of
DNA and a few other
things
Structures – Nuclear Membrane
 The Nuclear
Membrane
separates the nucleus
from the rest of the
cell
 The Nuclear
Membrane
disappears during
cell division
Structures - Chromosomes
Chromosomes
are visible when a
cell is dividing
 All species of plants
and animals have a
certain number of
chromosomes in their
body cells
Structures - Chromosomes
 Chromosomes are
made of two
chromatids
connected by a
centromere
Structures - Genes
Genes are
structures or locations
on the chromosomes
that carry information
for the cell’s activity
 Genes carry coded
instructions that are
similar to an
architect’s blueprint
Structures - DNA
DNA is the chemical
that makes up genes
and chromosomes
Structures - Centrioles
Centrioles are
organelles outside the
nucleus that anchor
the spindle fibers
Structures – Spindle Fibers
Spindle fibers form
when a cell is dividing
 They pull
chromosomes to
opposite ends of the
mother cell
Chromosome Numbers
 Examples
 All members of an animal
or plant species have the
same number of
chromosomes
 Man – 46 (23 pair)
Chromosomes
 Midge – 4 (2 pair)
 Crayfish – 208
 Fern – 768
 Pea – 14
 Corn – 20
 Monkey – 42
 Rabbit – 44
 Mouse – 4
 Moth – 62
 Potato – 48
 Tomato – 24
 Sunflower-34
 Frog-26
 Cow-60
 Horse-64
The Cell Cycle
 The cellscycle includes a
resting phase, the 4
phases of mitosis, and
cell separation.
Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
Mitosis - Interphase
 Interphase is a resting
phase - a period of
growth and
development where
the chromosomes are
not visible.
 Duplication of the
chromosomes takes
place (exact copies
are made)
Mitosis - Prophase
 In Prophase, the
chromosomes
become visible under
a microscope
 They become short,
thick, and paired up
 The nuclear
membrane begins to
disappear
Mitosis - Metaphase
 Nuclear Membrane
completely gone
 Pairs of
Chromosomes line up
in the middle of the
cell
 Spindle fibers attach
to the chromosome
pairs
Mitosis - Anaphase
 The chromosomes
are pulled apart and
the chromatids are
pulled and move to
the opposite ends of
the cell
Mitosis - Telophase
 Spindle fibers
disappear
 Chromosomes begin
to stretch out and lose
their rodlike
appearance.
 A new nuclear
membrane forms
around each region of
chromosomes.
Cytokinesis
 Cell membrane
pinches in around the
middle of the cell.
 The result is a new
daughter cell that is
identical to the parent
cell. It should have
the same number of
identical
chromosomes.