Cell Growth and
Division
Chapter 10
By the time you finish reading this
sentence, 50 million of your cells will
have died and been replaced by
others. Some are lost through 'wear
and tear’, some just reach the end of
their life, and others deliberately
self-destruct.



A. Importance of Cell Growth
and Division
Allows for an
organism’s growth
Replaces damaged
cells
Allows cells to
maintain the proper
surface area-tovolume ratio
WHY CAN’T A CELL JUST KEEP GETTING
BIGGER?
HOWEVER>>>>The
larger a cell becomes,
the more demands it
places on it’s DNA. It
also has more trouble
moving nutrients and
wastes across the cell
membrane.
Allows cells to maintain the proper
surface area-to-volume ratio


1. Cells cannot simply
grow by increasing in
size.
Cells of adults and
children of a species
are the same size.
•
•
•
The Cell membrane determines the surface
area of the cell.
The volume of a cell is determined by the
amount of cytoplasm present with all its
contents.
As a cell’s size increases, its volume
increases much faster than its surface area.


The cell overcomes
these problems
through the process
of cell division.
Ratio of Surface Area to
Volume
As the size of a cell increases, its
volume increases faster than the
surface area.
 The decrease in the cell’s ratio of
surface area to volume makes it
more difficult for the cell to move
needed materials in and waste
products out quickly enough for the
cell to survive.

Find surface area
Find surface area
Find surface area
Find surface area
Find Volume
Find Volume
Find Volume
Find Volume
Find Ratio
Find Ratio
Find Ratio
Find Ratio
How do little elephants grow up to be
BIG elephants?
Why do animals shed their
skin?
Cell Division!
More next time!
Quiz over Ch 10.1
Cell Growth
Next Time
Regulating Cell Division (Cell Cycle)
Cells stop
growing when
they come in
contact with
each othersuch as when a
wound is healing
Cyclins-proteins
within the cell
that regulate the
timing of
eukaryotic cell
division
a. Internal Cyclinsusually controls cell
division events inside
the cell like the
beginning and end of
cell cycle stages.
b. External Cyclins for events outside
the cell. These
usually speed up or
slow down the cell
cycle and heal
wounds.
CANCER
Occurs when cells do not respond
to normal signals that regulate
growth
*Most cancer cells have defect
in the p53 gene
Malignant Tumorinvasive
uncontrolled
growth of cells
Skin Cancer
Benign Tumor-a
tumor that only
grows in one place.
Noninvasive and
usually treatable
Cell Division!
Ch 10.2
Cell Reproduction


Prokaryotes
Bacteria
Eukaryotes
Plants & animals
Prokaryotes
 Lack
a nucleus
 Have a single chromosome
 Reproduce asexually by binary
fission
 Include bacteria
Steps in Binary Fission
Cells increase their
cell mass slightly
2. DNA & cell
components are
replicated
3. Each cell divides
into 2 daughter cells
1.
Binary Fission of Bacterial
Cell
E. Coli Dividing by Binary
Fission
Eukaryotes
 Contain
a nucleus &
membrane bound organelles
 Asexually reproduce cells by
mitosis
Vocabulary
Mitosis = division of the cell nucleus and
its contents
 Cytokinesis = the division of cell
cytoplasm into two identical daughter
cells
 Chromatin = the combination of DNA
and histone proteins
 Chromosome-main organelle involved in
Cell Cycle
 Diploid = Two copies of each
chromosome, one paternal, one maternal

Chromosomes
in the
Larger
Scheme
Chromosome
Structure
1 – Chromatidbecause each
has an identical
half they are
“sister”
chromatids
2 – Centromere
3 – Short arm
4 – Long arm
Chromosomes

Made from DNA
– Genetic material
 directs activities
 determines characteristics

Formed from chromatin
– Uncoiled DNA
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Chromosomes

(cont.)
Each chromosome (at this point) is
made up of 2 identical chromatids
– Joined strands of identical duplicated
genetic material

Joined at centromere
– Chromatids separate and each cell has
identical information

Formed in S phase of cell cycle
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From: http://www.rothamsted.bbsrc.ac.uk/
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notebook/courses/guide/chromo.htm
From: http://www.accessexcellence.org/RC/VL/GG/nucleosome.html
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Sets of chromosomes

Each human somatic (body) cell
– 23 pairs of chromosomes (46 total)

Homologous chromosomes
– Each pair is called homologous
 Similar in size, shape and genetic content
 Not identical!
 One from each parent
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Cell Cycle

Interphase
– G1 - growth and normal cell activity

G0 – never divides again
– S - Synthesis of DNA

DNA replication
– G2 - Growth for division, organelles double

Mitosis - Division of the nucleus
 Cytokinesis - Division of the cytoplasm (cell)
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Cell Cycle






Stages in growth
& division
G1 Phase
S Phase
G2 Phase
M Phase
Cytokinesis
Growth for division
Organelles double
Growth &
normal cell activity
G0
DNA replication
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Length of cell cycle

Ranges from 20 minutes to 20 hours
 Some cells divide constantly and others
never divide
– Muscle cells
– Red Blood cells
– Skin cells
– Bone cells
– Nerve cells
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G1 Phase
 First
growth stage
 Cell increases in size
 Cell prepares to copy its
DNA
Synthesis (S) Phase
 Copying
of all of DNA’s
instructions
 Chromosomes duplicated
G2 Phase
 Time
between DNA synthesis
& mitosis
 Cell continues growing
 Needed proteins produced
Mitosis

Significance of the
process of mitosis
A process in which eukaryotic cells form
two identical nuclei.
– Each cell receives a complete set of
chromosomes
– division of the nucleus

Cytokinesis
– division of the cytoplasm

2 independent cells (genetically identical)
– Different in plant and animals
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M Phase
 Cell
growth & protein
production stop
 Cell’s energy used to make 2
daughter cells
 Called mitosis or
karyokinesis (nuclear
division)
Life Cycle of a Cell
Mitosis is a cycle with no beginning or end.
Interphase – Resting Stage
 Cells
carrying on normal
activities
 Chromosomes aren’t visible
 Cell metabolism is occurring
 Occurs before mitosis
Interphase
D. Stages of Mitosis
 Prophase
 Metaphase
 Anaphase
 Telophase
Major Events in Mitosis
Cells Undergoing Mitosis
Steps in Prophase
1.
2.
3.
4.
5.
DNA coils tightly & becomes visible
as chromosomes
Nuclear membrane disappears
Nuceolus disappears
Centrioles migrate to poles
Spindle fibers begin to form and
the chromosomes attach
Eukaryotic Chromosome
Spindles attach here
Prophase
Animal Cell
Plant Cell
Spindle fibers
Centrioles
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Steps in Metaphase
 Spindle
fibers from
centrioles attach to each
chromosome
 Cell preparing to
separate its
chromosomes
 Cell aligns its
chromosomes in the
middle of the cell
Metaphase
Metaphase
Animal Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Plant Cell
Steps in Anaphase
 Cell
chromosomes are separated
 Spindle fibers shorten so
chromosomes pulled to ends of
cell
Mitotic Spindle
Anaphase
Anaphase
Animal Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Plant Cell
Steps in Telophase
 Separation
of
chromosomes completed
 Cell Plate forms
(plants)
 Cleavage furrow
forms(animals)
 Nucleus & nucleolus
reform
 Chromosomes uncoil
Telophase
Plant
Animal
Telophase
Animal Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Plant Cell
Cytokinesis
 Occurs
after chromosomes
separate
 Forms two, identical
daughter cells
Cytokinesis
Cell Plate Forming in Plant Cells
Animal Mitosis -- Review
Interphase
Prophase
Metaphase
Anaphase
Telophase
Interphase
Plant Mitosis -- Review
Interphase
Prophase
Metaphase
Anaphase
Telophase
Interphase
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From: http://www.kumc.edu/instruction/medicine/anatomy/histoweb/cytology/large/Cyt001.JPG
Page: 75
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http://virtual.yosemite.cc.ca.us/randerson/Lynn's%20Bioslides/45.jpg
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http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/Bio%20101/Bio%20101%20Laboratory/
Mitosis/Photographs/whitefish_mitosis_prophase_metaphase_anaphaseX400.jpg
Page: 77
http://faculty.clintoncc.suny.edu/faculty/michael.gregory/
files/Bio%20101/Bio%20101%20Laboratory/Mitosis
/Photographs/whitefish_mitosis_telophaseX400.jpg
http://faculty.clintoncc.suny.edu/faculty/michael.gregory/
files/Bio%20101/Bio%20101%20Laboratory/
Mitosis/Photographs/whitefish_mitosis_anaphaseX400.jpg
4/13/2015
Page: 78
Quiz
Next time!
Regulating Cell Division (Cell Cycle)
Cells stop
growing when
they come in
contact with
each othersuch as when a
wound is healing
Cyclins-proteins
within the cell
that regulate the
timing of
eukaryotic cell
division
a. Internal Cyclinsusually controls cell
division events inside
the cell like the
beginning and end of
cell cycle stages.
b. External Cyclins for events outside
the cell. These
usually speed up or
slow down the cell
cycle and heal
wounds.
Malignant Tumorinvasive
uncontrolled
growth of cells
Skin Cancer
Benign Tumor-a
tumor that only
grows in one place.
Noninvasive and
usually treatable
CANCER
Occurs when cells do not respond
to normal signals that regulate
growth
*Most cancer cells have defect
in the p53 gene
Make a little book
Page one – Title
 Page two – interphase including G1, S, G2
 Page three – prophase
 Page four – metaphase
 Page five – anaphase
 Page six – telephase
 Page seven – cytokinesis
 Page eight – the end

Test information

Cell Cycle
–
–
–
–

Order
S phase
Cancer
Interphase
Mitosis completed
– What does each cell have?


Chromosomes
Mitosis
–
–
–
–

Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
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