10 – 2 cell division mitosis. chromosomes dna is passed on in chromosomes dna is passed on in...
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10 – 2 Cell Division10 – 2 Cell Division
MitosisMitosis
ChromosomesChromosomes DNA is passed on in DNA is passed on in
chromosomes chromosomes Every organism has a specific # Every organism has a specific #
of chromosomes: of chromosomes:
fruit flies 8 fruit flies 8
humans 46humans 46
Before division called sister Before division called sister “chromatids”“chromatids” Chromatids are attached with a Chromatids are attached with a
centromerecentromere and become … and become …
Chromosomes Chromosomes are only are only visible during cell divisionvisible during cell division
The Cell CycleThe Cell Cycle
During the cell cycle, a During the cell cycle, a cell grows, prepares for cell grows, prepares for division, and divides to division, and divides to form 2 daughter cells, form 2 daughter cells, each of which then each of which then begins the cell cycle begins the cell cycle again.again.
1. Interphase1. Interphase = growth = growth 2. Mitosis2. Mitosis = division = division
Events of the Cell CycleEvents of the Cell Cycle InterphaseInterphase
Period of growthPeriod of growth Hereditary material is in the form of Hereditary material is in the form of
chromatinchromatin 3 stages:3 stages:
GG11 - “growth” - “growth” Increase in cell size in # of organelles, and Increase in cell size in # of organelles, and
in # of proteinsin # of proteins SS – “synthesis” – “synthesis”
DNA replication (chromatin is doubled)DNA replication (chromatin is doubled)
GG22 – “growth” – “growth” Continued cell growthContinued cell growth
nucleolus
chromatin
centrioles
Mitosis BeginsMitosis Begins
Mitosis is when a Mitosis is when a cell divides into two cell divides into two new cells.new cells.
Mitosis is one of the Mitosis is one of the shortest parts of a shortest parts of a cells life.cells life.
However, it has the However, it has the most stages.most stages.
CELLSALIVE.COM
Mitosis (1. prophase)Mitosis (1. prophase) MitosisMitosis – period of cell – period of cell
divisiondivision 4 stages:4 stages:
ProphaseProphase – “prepare” – “prepare” Longest phase of mitosisLongest phase of mitosis Chromatin coils up and Chromatin coils up and
forms chromosomesforms chromosomes Duplicated chromosmes Duplicated chromosmes
are made up of 2 are made up of 2 identical sister identical sister chromatids connected at chromatids connected at the centromeresthe centromeres
Sister chromatid
centromere
IdenticalSisterchromatid
Mitsosis (1. prophase)Mitsosis (1. prophase) Prophase (continued)Prophase (continued) Nucleolus and nuclear membrane Nucleolus and nuclear membrane
fade away, causing the nucleus to fade away, causing the nucleus to disappear.disappear.
Centrioles move to opposite ends of Centrioles move to opposite ends of the cellthe cell CentriolesCentrioles – cylindrical structures made – cylindrical structures made
of microtublesof microtubles Spindle fibersSpindle fibers form between the form between the
centriolescentrioles SpindleSpindle – Pulls the sister chromatides – Pulls the sister chromatides
apart.apart.
*the spindle attaches to the *the spindle attaches to the chromosome at the centromere*chromosome at the centromere*
spindle
centriole
Mitosis (2. Metaphase)Mitosis (2. Metaphase)
MetaphaseMetaphase “middle” “middle” Chromosomes attach Chromosomes attach
to the spindle fibers to the spindle fibers at their centromereat their centromere
Chromosomes line Chromosomes line up along the middle up along the middle of the cell (equator)of the cell (equator)
Mitosis (3. Anaphase)Mitosis (3. Anaphase)
AnaphaseAnaphase – – “apart”“apart” Sister Sister
chromatids are chromatids are pulled apart by pulled apart by centrioles.centrioles.
Mitosis (4. Telophase)Mitosis (4. Telophase) TelophaseTelophase – “tear into two” – “tear into two”
Chromatids reach the opposite Chromatids reach the opposite sides (pole) of the cellsides (pole) of the cell
Chromosomes uncoil or unwind Chromosomes uncoil or unwind (chromatin)(chromatin)
Spindle fibers begin to break Spindle fibers begin to break downdown
Nucleolus reappearsNucleolus reappears New nuclear membrane forms New nuclear membrane forms
around each new set of around each new set of chromosomeschromosomes
Plasma membrane begins to Plasma membrane begins to separate into 2 new nucleiseparate into 2 new nuclei
Cytokinesis Cytokinesis
Division of cytoplasmDivision of cytoplasm In animals: “cleavage In animals: “cleavage
furrow” pinches the furrow” pinches the plasma membrane to plasma membrane to divide the cytoplasmdivide the cytoplasm
In plants: “cell plate” In plants: “cell plate” forms to divide the forms to divide the cytoplasmcytoplasm
Cell division-again!Cell division-again!
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