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Chapter 5:
Cell Growth and
Division
Mitosis Rap
Where is all the genetic information found in a cell?
• On the genes on the
Chromosomes
• Chromosomes are
actually strands of DNA
and proteins
• If cells were the size of a
basketball, your DNA
would stretch 40 miles
• We have 6 feet of DNA in
each cell!!!!!
Every species has a set number of chromosomes
• Chromosome number:
– Number of Chromosomes in a body cell
• Specific for each species of organisms. List
–
–
–
–
–
–
–
–
–
–
–
–
Human – 46
Chimpanzee – 48
Gorilla – 48
Potato – 48
Bat – 44
Fruit fly – 8
Mosquito – 6
King Crab – 208
Dog - 78
Horse – 64
Donkey - 62
Adder’s tongue fern
1,262
How would you duplicate a cell exactly to be certain that
both new cells have the identical DNA in each cell?
1. Duplicate the DNA first (this is DNA
replication)
2. Find a way to be certain that the DNA does
not get broken or tangled during the
process of dividing it into the two new
cells
3. Be certain that the new daughter cells will
have the exact same set of DNA in each
new cell’s nucleus
4. Divide up the cell’s contents. (Cytokinesis)
What would happen if a cell were to just split
into two without any advance preparation?
Instead, it is more efficient to
• shorten
Imagineuptrying
to divide
up
and then
organized
the
replicated
DNA
pieces
of yarn
byprior
colortoif
dividing
theall
DNA
upthrown
evenly into
they were
just
two
intocells.
a pile together.
This
is whattake
happens
in The
–It would
a long
timeCell
to
Cycle
do this efficiently and
accurately.
Chromosome structure
• Before cell division occurs, the DNA is loose
in the nucleus and known as Chromatin
• DNA starts coiling around proteins called
histones (like thread on a spool)
• DNA shortens up
Chromosome
Coiling animation
• The two identical chromosomes that resulted
from DNA replication will find each other and
come together. The two “twins” are called
chromatids & are held together by a
centromere
This strand of DNA is identical
to this strand of DNA.
Chromatid
Sister
Chromatids
Label the structures on the
Paired Chromosomes
Why do cells need to
reproduce?
• Necessary for:
– Repair and replacement of damaged cells
– Growth (remember your first baby picture)
– Smaller cells are more efficient than are
larger cells.
What would happen to a cell if it continued to grow?
Calculate the Surface area (Length x width x 6) and Volume (Length3) then
the Surface area to Volume ratio (reduce to lowest terms)
As the size of the cell increases, its volume increases faster than its
surface area.
Surface area to volume ratio would decrease.
Makes it difficult to move needed materials in and wastes out of the
cell efficiently.
The Cell Cycle
• Entire process that a cell undergoes in
cell division from start to finish.
• Cells:
1.
2.
3.
4.
–
grow
prepare for division
divide to form two daughter cells
begin the cell cycle over again.
Cells such as skin, lining of digestive
tract and blood cells go through this
process frequently
– Introduction
Stomach
lining cells: 2 days
______________________
Platelets: 10 days
______________________
Skin Cells: 20 days
____________________
Red Blood Cells: 120 days
______________________
Brain cells: 30-50 years
______________________
Intestinal
lining cells: 3 days
______________________
The Cell
Cycle
•
Interphase Divided into 2 parts
– G1 - Cell grows from last cell cycle
– S – Synthesis of DNA (DNA makes a copy of
itself)
– G2 – Cell growth and gets ready for cell
division
– G0 – No cell division – typical of cells like
nerve cells that stop dividing at maturity
• Mitosis – M phase
– Prophase
– Metaphase
– Anaphase
– Telophase
– Cytokinesis
How long does the Cell Cycle take in
a human cell?
Studies have shown that
the average cell works
on a 24 hr cycle as does
typical cell replication.
Embryonic cells will
divide every 8 minutes!!
Liver cells could take up
to a year.
However, many cells will
be in G0 for long periods
of time.
Interphase
• Longest phase in
the Cell Cycle
– over half the time
is spent in this
phase
• Prophase
– longest phase in Mitosis
1. Chromosomes are visible
2. Chromatids pair up
3. Centrioles (if animal cell) migrate to poles
4. Nuclear envelope & nucleolus start to
break down
5. Fibers form
Nuclear
Sister
Chromatids Membrane &
Centrioles
Fibers
Nucleolus
Shorten and
Thicken
Begins to
break down
Move apart
from one
another
Form between
centrioles (in
animal cells)
• Metaphase
– shortest part of
Mitosis
1. Sister
Chromatids line
up on the
equator (middle)
Sister
Chromatids
Become
attached to
the fibers.
Are moved to
middle of cell
Nuclear
Centrioles
Membrane
Remains
dissolved
At opposite
ends of cells
Fibers
Go from the
poles to
centromeres
• Anaphase
– “An away they go!”
1. Chromatids separate
2. Go to opposite poles.
Now called chromosomes!!
1. Fibers shorten up
Sister
Chromatids
Pulled apart by
fibers.
Each chromatid
is separate from
its “sister”
Now called a
chromosome
Nuclear
Membrane
Remains
dissolved
Centrioles
Still at cell’s
poles;
Fibers
Pull each
chromosom
e toward
opposite
ends of the
cell
• Telophase
– “the end” – Final phase
1.Chromosomes reach opposite ends
2.Cell membrane pinches in or Cell plate
forms (if plants)
3.Chromosomes uncoil
4.Nuclear membrane & nucleolus reappear
5.Fibers disappear
Sister
Nuclear
Chromatids Membrane &
Nucleolus
Cell
Membrane
Each end of
cell has a
complete set of
identical
chromosomes.
Begins to
pinch, forming
two new cells
Begins to
reform
Fibers
Begin to
disappear
• Cytokinesis
Dividing up of cellular
contents.
Occurs simultaneously
with Telophase
Mitosis and Cytokinesis
• Cytokinesis differs in animal and plant cells.
In animal cells, the
membrane
pinches closed.
In plant cells, a cell
plate forms.
What was the point of Mitosis?
• Results in two identical daughter cells
• Each cell will have the SAME number of
chromosomes as the original cell
• Each cell will have the SAME function
as the original cells
Mitosis animations
Try them all!
• http://www.sumanasinc.com/webcontent/animations/
content/mitosis.html
• cellsalive.
• John Kryk
• You tube (really good)
• Hybrid (love the music)
• http://www.csuchico.edu/~jbell/Biol207/animations/m
itosis.html
• Arizona
Mitosis Rap
• Movie Clip
• McGraw
Mitosis Another
Interphase
Prophase
Anaphase
Metaphase
Late Prophase
Telophase
Checking your understanding Mitosis
Starting with Prophase, draw a cell undergoing mitosis. Your original cell
has 4 chromosomes.
Make certain to include the nuclear membrane, nucleolus, chromatids,
centrioles (animal cell), chromosomes and spindles.
Give the events
occurring in
each of the
stages of the
Cell Cycle
_______________
_______________
_______________
_______________
_______________
_______________
_______________
_______________
_______________
_______________
_______________
_______________
_______________
_______________
_______________
_______________
_______________
_______________
_______________
_______________
Interphase
Metaphase
Telophase
Prophase
Anaphase
___________________
___________________
___________________
___________________
___________________
___________________
• Cancer cells are abnormal cell growth due to either a:
• malfunction in the Cell Cycle
• change in the genes during DNA replication during
the S phase of Interphase
Cancer cells do not carry out normal, necessary
functions.
• Cancer cells form disorganized clumps called tumors.
• Benign tumors remain clustered and can be removed.
• Malignant tumors metastasize, or break away, and can
form more tumors.
Blood cells
Normal cells
Mutated cell
Cancerous
cells
• Carcinogens are substances known to promote
cancer.
• UV radiation
• Chemicals such as formaldehyde, asbestos, arsenic, benzene…
• Tobacco smoke
• Standard cancer treatments typically kill both cancerous
and healthy cells.
Stem cells are unique body cells.
• Stem cells have the ability to
– divide and renew themselves
– remain undifferentiated in form
– develop into a variety of specialized cell types
Some people save the
placenta or umbilical
cord to harvest these
• The use of stem cells offers many currently
realized and potential benefits.
– Stem cells are used to treat leukemia and lymphoma.
– Stem cells may cure disease or replace damaged
organs.
– Stem cells may revolutionize the drug development
process.
Henrietta Lacks
The Immortal Hela cells
• Basic Information
• Please Do Now:
– Write 4 LINES about your reaction to this
video
• Was the action of the scientists right or wrong?
Why?
• Include at least 1 fact about cancer from your
notes or the video.