Download Mitosis

 REPAIRS BROKEN BONES,
BURNS, CUTS, AND SCRAPES?
 CAUSES CANCER?
 TRANSFORMS US FROM 2
CELLS TO 20 BILLION?
 Allows organisms, including
you, to GROW
 Replace old cells
 Increases the number of cells

Every day billions of red blood cells in your body
are destroyed and need to be replaced --- HOW?
MITOSIS

During the time it takes to read this sentence, 6
million new red blood cells were produced!
Begins with organism’s
formation or birth
Growth and Development
Death
Individual cells follow the same life cycle
 Cell Cycle:
series of events that
takes place from one cell division
to the next
 Not the same for all cells
 Examples
▪ Bean Plants 19hours
▪ Animal Embryos 20 min
1.
2.
INTERPHASE
MITOSIS
1. PROPHASE
2. METAPHASE
3. ANAPHASE
4. TELOPHASE
 Period of growth &development
 Before a cell can divide, a copy of its
hereditary material must be made
 So each new cell can receive a copy
 Nucleus divides & cytoplasm
separates
 Mitosis:
nucleus divides to form
two identical nuclei
 Steps
1.
2.
3.
4.
Prophase
Metaphse
Anaphase
Telophase
 A Chromosome is a structure
that contains the cell’s
hereditary material (DNA)
 Found inside the nucleus
When cells are ready to divide, each
duplicated chromosome condenses into
thick strands called chromatids
 Chromatids: duplicated chromosomes
formed during interphase that are thick
and coiled together

 Needed for mitosis
Centromere
Chromatids are
tightly coiled
together
 Nucleolus and
nuclear membrane
disintegrate
 Spindle fibers begin
to stretch across the
cell

 The chromatid
pairs line up
along the
equator (or
middle) of the
cell
Pairs of
chromosomes
are separated
 Each half of the
chromatid is
pulled to an
opposite side of
the cell

 Spindles
disappear
 Chromosomes
uncoil
 New nucleus
forms
 Mitosis ends
Cytokinesis
After mitosis
 Cytoplasm
separates
 Cell membrane
moves inward
and pinches off

 = TWO separate
cells
 Division of the nucleus
 Produces two new nuclei that are
identical to each other and the
original cell
 Each cell in your body has 46
chromosomes or 23 pairs
 Each new cell also has 46
chromosomes
 Sexual reproduction requires two
organisms
 Asexual reproduction: a new
organism is produced from one
parent
 Produces offspring that are identical
to parent
Reproduce
asexually
 Produce
horizontal stems
called runners
that create new
strawberries



Bacteria CANNOT
reproduce by mitosis
They are prokaryotic –
 NO Nucleus

Reproduce by fission
 Used by cells with no
nucleus to copy genetic
information and divide
New organism
grows from the
body of the
parent
 When the bud is
large enough it
breaks away to
live on its own

 Some
organisms can
regrow
damaged or
lost body parts
 Sea Stars


Cancer is the result of errors during mitosis
Normally healthy cells being reproducing out
of control and can grow into structures called
tumors