CHAPTER 10 GROWTH AND DIVISION
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Transcript of CHAPTER 10 GROWTH AND DIVISION
CHAPTER 10GROWTH
ANDDIVISION
Cell reproduction is differentin prokaryotes than in eukaryotes.
ProkaryotesLack a nucleusHave a single chromosomeReproduce by binary fission
E. Coli Reproducing by binary fission
EukaryotesHave a nucleus and membrane bound organellesReproduce by mitosis (asexual)
Parent Cell
Daughter cells
In most cases, living things grow by producing more cells.
2 main reasonswhy cells divideare: 1) too large ademand on DNA2) difficulty movingenough materialsacross the cellmembrane
If a cell continuedto grow largerwithout dividing, its DNA would nolonger be able to meet the cell’sneeds
The rate of exchange of materials acrossthe membrane depends on thesurface area of the cell; while the rate at which foodand oxygen are used up and wastes are produced depends on the cell’s volume.
As a cell increases in size, thevolume increases much morequickly than the surface area.this causes problems in moving sufficient materials across the membrane.
Cell division solves the problemof moving enough materials byincreasing the surface area of the cell and solves the problemof insufficient DNA by replicating the chromosomes(making a copy of the DNA).
Before it becomes too large, agrowing cell divides formingtwo “daughter” cells in theprocess called cell division.
CELL CYCLE
Phases of the Cell CycleG1 phaseS (synthesis) phaseG2 phaseM phase (mitosis)
G1, S, and G2 are collectivelycalled Interphase.
INTERPHASE
G1 PHASEFirst growth stageCell increases in sizeSynthesize new proteins and
organelles
DNA molecules are synthesizedChromosomes duplicated
S phase
Time between DNA synthesis & mitosis
Cell continues growingNeeded proteins and organelles produced
G2 phase
M PHASECell growth & protein production stop
Cell’s energy used to make 2 daughter cells
Called mitosis or karyokinesis (nuclear division)
Only occurs in eukaryotes
M phase orMitosis is Divided into4 sub phases:ProphaseMetaphaseAnaphaseTelophase
CELLS UNDERGOING MITOSIS
ProphaseLongest phaseChromosomes become visibleCentrioles move to poles of cellNuclear membrane breaks down
Nucleolus disappearsChromosomes attach to spindle at centromere
23Nucleus & Nucleolus have disintegrated
Chromosomes
Chromosomes
Nucleolus Cytoplasm
Nuclear Membrane
HUMAN CHROMOSOMES
MetaphaseChromosomes line up along equator of cellMicrotubules connect centromeres to pole of spindle
METAPHASE
STEPS IN ANAPHASE
Chromosomes are separated Spindle fibers shorten so chromosomes are pulled to poles of cell
MITOTIC SPINDLE
ANAPHASE
STEPS IN TELOPHASE Separation of chromosomes completed Cell plate forms (plants) Cleavage furrow forms(animals) Nucleus & nucleolus reform Chromosomes uncoil
TELOPHASE
Plant Animal
CYTOKINESIS
Occurs after chromosomes separate
Forms two, identical daughter cells
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CYTOKINESISCleavage furrow in animal cell
Cell plate in plant cell
NO. ALL CELLS DO NOT MOVE THROUGH THE CELL CYCLE AT THE SAME RATE.MUSCLE CELLS AND NERVE CELLS DO NOT DIVIDE ONCE THEY HAVE DEVELOPED.51. SKIN, DIGESTIVE TRACT, AND BONE MARROW CELLS DIVIDE RAPIDLY THROUGHOUT LIFE.
YES. THE CONTROLS ON CELL GROWTH AND CELL DIVISION CAN BE TURNED ON AND OFF.
THE PROCESS OF CELL DIVISION IS TURNED ON WHEN AN INJURY OCCURS. THE CELLS AT THE EDGE OF THE INJURY ARE STIMULATED TO DIVIDE RAPIDLY.
CANCER IS A DISORDER IN WHICH SOME OF THE BODY’S OWN CELLS LOSE THE ABILITY TO CONTROL GROWTH.
CANCER CELLS DO NOT RESPOND TO THE SIGNALS THAT REGULATE THE GROWTH OF MOST CELLS. CANCER CELLS DIVIDE UNCONTROLLABLY AND FORM MASSES OF CELLS CALLED TUMORS. TUMORS ARE HARMFUL BECAUSE THEY DAMAGE SURROUNDING TISSUES.
CANCER MAY BE CAUSED BY TOBACCO, RADIATION, OR VIRAL INFECTION.
ALL CANCERS HAVE ONE THING IN COMMON: THE CONTROL OVER THE CELL CYCLE HAS BROKEN DOWN.
A LARGE NUMBER OF CANCER CELLS HAVE A DEFECT IN THE P53 GENE. THE P53 GENE NORMALLY HALTS THE CELL CYCLE UNTIL ALL CHROMOSOMES HAVE BEEN REPLICATED.
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MITOSIS ANIMATIONName each stage as you see it occur?
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TEST YOURSELF OVER MITOSIS
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MITOSIS QUIZ
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NAME THE STAGES OF MITOSIS:
Interphase
Early prophase
Mid-ProphaseLate Prophase
Metaphase
Late Anaphase
Early Anaphase
Early Telophase, Begin cytokinesis
Late telophase, Advanced cytokinesis
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IDENTIFY THE STAGES
Early, Middle, & Late Prophase
Late ProphaseMetaphase Anaphase
Late Anaphase Telophase Telophase & Cytokinesis
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LOCATE THE FOUR MITOTIC STAGES IN PLANTS
Metaphase
Prophase
Anaphase
Telophase