a review about mitosis and meiosis and different stages of cell cycle.

1. 11
RIDDHI SRIVASTAVA
15BBT0142
SLOT- E1+TE1

2.  GG11 - primary growth phase- primary growth phase
 S – synthesis; DNA replicatedS – synthesis; DNA replicated
 GG22 - secondary growth phase- secondary growth phase
collectively these 3 stages arecollectively these 3 stages are
called interphasecalled interphase
 M - mitosisM - mitosis
 C - cytokinesisC - cytokinesis
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3. 33

4. 44

5.  Division of theDivision of the
nucleusnucleus
 Also calledAlso called
karyokinesiskaryokinesis
 Only occurs inOnly occurs in
eukaryoteseukaryotes
 HasHas fourfour stagesstages
 Doesn’t occur inDoesn’t occur in
some cells such assome cells such as
brain cellsbrain cells
55

6.  ChromatinChromatin in nucleus condenses to formin nucleus condenses to form
visible chromosomesvisible chromosomes
 Mitotic spindleMitotic spindle forms from fibers informs from fibers in
cytoskeleton orcytoskeleton or centrioles (animal)centrioles (animal)
66
ChromosomesChromosomes
NucleolusNucleolus CytoplasmCytoplasm
Nuclear MembraneNuclear Membrane

7. 77
What the cellWhat the cell
looks likelooks like
What’s happeningWhat’s happening

8. Chromosomes, attached to theChromosomes, attached to the kinetochorekinetochore
fibersfibers, move to the center of the cell, move to the center of the cell
Chromosomes are now lined up at the equatorChromosomes are now lined up at the equator
88
Pole ofPole of
the Cellthe Cell
Equator of CellEquator of Cell

9. 99
What the cell looksWhat the cell looks
likelike
What’sWhat’s
occurringoccurring

10.  OccursOccurs rapidlyrapidly
 SisterSister
chromatidschromatids areare
pulled apart topulled apart to
opposite polesopposite poles
of the cell byof the cell by
kinetochorekinetochore
fibersfibers
1010

11. 1111
What theWhat the
cell lookscell looks
likelike
What’sWhat’s
occurringoccurring

12. Sister chromatids atSister chromatids at oppositeopposite
polespoles
SpindleSpindle disassemblesdisassembles
Nuclear envelopeNuclear envelope forms aroundforms around
each set of sister chromatidseach set of sister chromatids
NucleolusNucleolus reappearsreappears
CYTOKINESISCYTOKINESIS occursoccurs
Chromosomes reappear asChromosomes reappear as
chromatinchromatin 1212

13.  Means division of the cytoplasmMeans division of the cytoplasm
 DivisionDivision of cell into two,of cell into two,
identical halves calledidentical halves called daughterdaughter
cellscells
 In plant cells, cell plateIn plant cells, cell plate formsforms
at the equator to divide cellat the equator to divide cell
 In animal cells,In animal cells, cleavage furrowcleavage furrow
forms to split cellforms to split cell
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14. 1414
Cleavage furrowCleavage furrow
in animal cellin animal cell
Cell plate inCell plate in
animal cellanimal cell

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16.  Preceded by interphase whichPreceded by interphase which
includesincludes chromosome replicationchromosome replication
 TwoTwo meiotic divisions ---meiotic divisions --- Meiosis IMeiosis I
and Meiosis IIand Meiosis II
 Called Reduction- divisionCalled Reduction- division
 Original cell is diploid (2n)Original cell is diploid (2n)
 Four daughter cellsFour daughter cells produced thatproduced that
areare monoploid (1n)monoploid (1n)
1616

17.  Daughter cellsDaughter cells contain half thecontain half the
number of chromosomesnumber of chromosomes as theas the
original celloriginal cell
 ProducesProduces gametesgametes (eggs & sperm(eggs & sperm))
 Occurs in theOccurs in the testestestes in malesin males
((SpermatogenesisSpermatogenesis))
 Occurs in theOccurs in the ovariesovaries in femalesin females
((OogenesisOogenesis))
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18. 1818
 Start withStart with 46 double stranded46 double stranded
chromosomes (2n)chromosomes (2n)
After 1 division -After 1 division - 23 double23 double
stranded chromosomes (n)stranded chromosomes (n)
After 2nd division -After 2nd division - 23 single23 single
stranded chromosomes (n)stranded chromosomes (n)
 Occurs in ourOccurs in our germ cellsgerm cells thatthat
produce gametesproduce gametes

19. 1919
Early prophaseEarly prophase
Homologs pair.Homologs pair.
Crossing overCrossing over
occursoccurs.
Late prophaseLate prophase
Chromosomes condense.Chromosomes condense.
Spindle forms.Spindle forms.
Nuclear envelopeNuclear envelope
fragments.fragments.

20.  HomologousHomologous
chromosomeschromosomes in ain a
tetradtetrad cross overcross over
each othereach other
 Pieces ofPieces of
chromosomes orchromosomes or
genes aregenes are
exchangedexchanged
 ProducesProduces GeneticGenetic
recombinationrecombination inin
the offspringthe offspring
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21. 2121
Homologous pairsHomologous pairs
of chromosomesof chromosomes
align along thealign along the
equatorequator of theof the
cellcell

22. 2222
Homologs separateHomologs separate andand
move to opposite poles.move to opposite poles.
Sister chromatidsSister chromatids remainremain
attachedattached at theirat their
centromerescentromeres.

23. 2323
Nuclear envelopesNuclear envelopes
reassemble.reassemble.
Spindle disappears.Spindle disappears.
CytokinesisCytokinesis divides celldivides cell
into two.into two.

24. Only one homolog of eachOnly one homolog of each
chromosome is present inchromosome is present in
the cellthe cell.
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Meiosis II produces gametes withMeiosis II produces gametes with
one copy of each chromosome andone copy of each chromosome and
thus one copy of each gene.thus one copy of each gene.
Sister chromatids carrySister chromatids carry
identical geneticidentical genetic
informationinformation..
Gene XGene X

25. 2525
ProphaseProphase
IIII
MetaphaseMetaphase
IIII
AnaphaseAnaphase
IIII
TelophaseTelophase
IIII 4 Identical4 Identical
haploid cellshaploid cells

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Nuclear envelopeNuclear envelope
fragments.fragments.
Spindle forms.Spindle forms.

27. 2727
Chromosomes alignChromosomes align
alongalong equatorequator of cellof cell..

28. 2828
Sister chromatidsSister chromatids
separate andseparate and
move tomove to oppositeopposite
polespoles.
EquatorEquator
PolePole

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Nuclear envelopeNuclear envelope
assembles.assembles.
ChromosomesChromosomes
decondense.decondense.
Spindle disappears.Spindle disappears.
Cytokinesis dividesCytokinesis divides
cell into two.cell into two.

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Gametes (egg & sperm)Gametes (egg & sperm)
formform
Four haploid cells withFour haploid cells with
one copy of eachone copy of each
chromosomechromosome
One allele of each geneOne allele of each gene
Different combinations ofDifferent combinations of
alleles for differentalleles for different
genes along thegenes along the
chromosomechromosome