Download - 13346 CellCycle&Mitosis
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Cell Cycle&
Mitosis
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Cell Reproduction
Cell Theory Cells come from preexisting cells
Cell division - process which ends with newcells formed from an old cell.
All organisms grow and change; worn outtissues are repaired or replaced by new cells
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CHROMwords
Chromatin uncoiledDNA + proteins
Chromosome coiledDNA + proteins (Looks likean X)
Chromatid only half of a chromosome
Sister chromatids Two chromatids joinedtogether, by a centromere,to form a chromosome
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Chromosomes
Contain DNA
Becomes dark when stained
Carriers of genetic material that is copiedand passed from generation to generation
Identity of cell
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Chromatin
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Cell CycleThe sequence of growth and divisionof the cellTwo general periods
Growth(interphase)
Division (mitosis)Majority of time isspent in the growthperiod known asInterphase
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The entire sequence of events happening fromThe end of one nuclear division to the beginningof the next.Involves following cycles:-1. Chromosome cycle:- In it, DNA synth. Alternateswith mitosis.2. Cytoplasmic cycle:- In it, cell growth alternates with
Cytokinesis.3. Centrosome cycle:- Both the above cycles require
proper inheritance of centrosome and its distributionon poles.
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Cell Cycle
Four stages to the cellcycle (by Howard &
Pelc, 1953) Growth period -
Interphase includes:G1S StageG2
Division period -Includes:
Mitosis
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Interphase:
Known as thegrowth period
Majority of cellslifeThree stageswithin Interphase
G1 S Stage G2
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G1Stage #1
Chromosomes are notvisible under a
microscope - becausethey are uncoiled,therefore calledchromatin
Proteins are quicklymade
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S Stage
Stage #2Chromatin isreplicated in the
nucleus
Chromatin divides toform sister
chromatids whichare connected bycentromeres
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G2Stage #3
Chromatin shortens and coils
Organelles are made
Most proteins made are for mitosis
Animals - centriole pair replicates and prepares toform spindle fibers.
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Interphase InformationBusiest phase of cell cycleReplication of chromosomesMost protein production
Organelles madeCell parts madePackaging of chromatins atthe latter part of interphase
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Mitosis
Four Phases of mitosis
Prophase Metaphase Anaphase Telophase
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Prophasefirst phase of mitosis
Longest PhaseChromatin coils up intovisible chromosomes
Chromosomes lookhairyEach chromosome nowhas two halves
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Prophasefirst phase of mitosis
Chromosomes are also called sister chromatids Two sister chromatids can be
called a diploid chromosome One sister chromatid can also be
called a haploid chromosome DNA in sister chromatids are
alike Sister chromatids are held
together by a centromere
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Prophase
first phase of mitosisNucleus disappears
Nuclear envelopedisintigrates
Nucleolus disintigrates
Completely absent by theend of prophase
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Prophasefirst phase of mitosis
ANIMAL CELLS Centrioles begin to go to
opposite ends of the cell Centrioles are small dark and
cylinder like Centrioles help to separatesister chromatids
ANIMAL AND PLANT CELLS Spindles begin to appear -
look like footballs Spindles have fibers in them
which help to separate sister chromatids
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Metaphase
second stage of mitosisShort stageSister chromatidsline up at theequator Sister chromatidsare attached by their centromeres to thespindle fibers
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Anaphasethird stage of mitosis
SC are pulled apart atthe centromere toopposite ends of thecell
This ensures that eachnew cell gets one set of the information needed
SC are pulled apartbecause the spindlefiber shortens
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Telophase
fourth stage of mitosisChromatids reach opposite polesof cellChromosomes unwindSpindle breaks downNucleolus reappearsNew nuclear envelope formsaround each set of chromosomesNew double membrane begins toform between the two newnuclei.
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Cytokinesis
end of telophaseThe dividing of thecytoplasm
ANIMALS Plasma membrane
pinches along theequator
Two new cells areseparated
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Cytokinesisend of telophase
PLANTS B/c rigid cell wall:
Cell plate is laid across the equator Cell membrane forms around each cellNew cell walls fom on each side of the cellplate until separation is complete
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P rophase
Metaphase
Anaphase
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Mitosis: Significance
Guarantees genetic continuity
Results in two new cells, daughter cells
Daughter cells carry out samefunction and cellular process as theparent cell
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Cells
Cells can function on their own or together as a group.
One-celled organisms remain one-celled
Multicellular organisms use mitosis toreplace and replenish their existing cells
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http://www.sinauer.com/cooper5e/animation1604.html
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