Download The Cell Cycle and Mitosis Notes

11/18/16
The Cell Cycle
and Mitosis
Notes
Page ___
Biology is the only
subject in which
multiplication is the
same thing as division…
THE CELL CYCLE
•  Series of events that cells go through as they
grow and divide
•  Consists of four phases:
–  G1 PHASE – CELL GROWTH
–  S PHASE – CHROMOSOME REPLICATION
–  G2 PHASE – PREPARATION FOR MITOSIS
–  M PHASE – MITOSIS AND CYTOKINESIS
Cell Cycle: order does matter!
•  Remember:
Cell Cycle phases as
IPMAT
•  I= Interphase (G1, S, G2
phases)
•  P= Prophase (M phase)
•  M= Metaphase (M phase)
•  A= Anaphase (M phase)
•  T= Telophase (M phase)
MITOSIS:
Making New Body Cells
Making New DNA
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Where it all began…
And now look at you…
You started as a cell smaller than
a period at the end of a sentence…
How did you
get from there
to here?
Getting from there to here…
•  Going from egg to baby….
the original fertilized egg has to divide…
and divide…
and divide…
and divide…
Why do cells divide…
"  One-celled organisms
# 
# 
for reproduction
asexual reproduction (clones)
amoeba
"  Multi-celled organisms
# 
for growth & development
# 
for repair & replacement
"  from fertilized egg to adult
starfish
"  replace cells that die from
normal wear & tear or from injury
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Dividing cells…
Copying DNA
•  What has to be copied
•  A dividing cell duplicates its DNA
–  DNA
–  organelles
–  cell membrane
–  lots of other
molecules
–  creates 2 copies of all DNA
–  separates the 2 copies to opposite ends of
the cell
–  splits into 2 daughter cells
DNA
•  enzymes
cell
plant cell
animal cell
nucleus
Organizing & packaging DNA
" But the DNA starts
loosely wound in the
nucleus
" If you tried to divide it
like that, it could
tangle & break
Chromosomes of Human Female
DNA
46 chromosomes
23 pairs
cell
nucleus
DNA has been
wound up
DNA in chromosomes in
everyday working cell
cell
nucleus
4 chromosomes
in this organism
DNA in chromosomes in cell
getting ready to divide
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Chromosomes of Human Male
double-stranded
human chromosomes
ready for mitosis
46 chromosomes
23 pairs
MITOSIS=body cells
DNA must be duplicated…
chromosomes in cell
DNA in chromosomes
cell
nucleus
•  Asexual reproduction for single cells
(remember: My toe needs to grow; this does
not need a partner !)
4 single-stranded chromosomes
•  Growth & development for multicellular organisms
•  Four phases of Mitosis: (Hint: PMAT)
1st P= Prophase
duplicated chromosomes
duplicated
chromosomes
cell
2nd M= Metaphase
3rd A= Anaphase
4th T= Telophase
4 double-stranded chromosomes
nucleus
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Mitosis: Dividing DNA & cells
•  Stage 2: DNA winds into chromosomes
•  Stage 1: cell copies DNA
–  DNA is wound up into chromosomes to keep it
organized
Copy DNA!
DNA
Mitosis: Dividing DNA & cells
duplicated chromosomes
Wind up!
cell
cell
nucleus
(prophase)
Cells spend the most time in Interphase
nucleus
(interphase)
Mitosis: Dividing DNA & cells
•  Stage 3: Chromosomes line up
–  chromosomes line up in middle
–  attached to protein cables that will help them
move
Line up!
duplicated chromosomes
lined up in middle of cell
(metaphase)
Mitosis: Dividing DNA & cells
•  Stage 4: Chromosomes separate
–  chromosomes split, separating pairs
–  start moving to opposite ends
Separate!
chromosomes split &
move to opposite ends
(pull apart)
(anaphase)
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Mitosis: Dividing DNA & cells
•  Stage 5: Cell starts to divide
Mitosis: Dividing DNA & cells
•  Stage 6: DNA unwinds again
–  cells start to divide
–  nucleus forms again
–  cells separate
–  now they can do their every day jobs
Divide! Makes 2
new cells
(telophase)
New daughter cells
Bye Bye!
(cytokinesis)
Cell division in Animals
•  Get 2 exact copies of original cells
–  same DNA
–  clones
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Mitosis in whitefish embryo
Mitosis in plant cell
Overview of mitosis
interphase
I.P.M.A.T.C.
prophase
Please Make Another Two Cells
cytokinesis
metaphase
anaphase
telophase
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REGULATING THE CELL
CYCLE
•  REGULATORY PROTEINS (Cyclins)
–  CONTROL CELL GROWTH
–  STIMULATES THE CELL TO PRODUCE SPINDLE AND BEGIN
CELL DIVISION
–  NORMAL CELLS STOP GROWING WHEN THEY COME INTO
CONTACT WITH EACH OTHER
What happens when there is Cancer
Cells?
•  Cancer Cells
–  Don t respond to signals
that control the cell cycle
–  Do not stop dividing
–  Can form tumors
•  Carcinogens
–  Damage DNA, results in
cancer
–  Radiation
–  Cigarette smoke
–  Environmental chemicals
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