Meiosis Poster

Poster for AQA Biology AS Level on Meiosis 

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  • Created by: JH
  • Created on: 25-04-12 07:46
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3.2.2 DNA is an information-carrying molecule. Its sequence of bases Independentsegregationofhomologouschromo-
determines the structure of proteins, including enzymes. PROPHASE 1: MEIOSIS 2: ANAPHASE 2:
somes.
Theimportanceofmeiosisinproducingcellswhicharegeneticallydifferent.Within --Chromosomescondense
--Chromatidsmoveapart.
--Fibrespullchromosomes
towardseachpole Thistakersplaceduringmeiosis1andeachchro-
thisunit,meiosisshouldbestudiedonlyinsufficientdetailtoshow --Nuclearenvelopedisperses
Attheendfourcellsare
--
mosomelinesupwithitshomologouspair.These
· the formation of haploid cells formed.
Crossingoverandrealign-
-- homologouspairsarrangesthemselvesrandomly
· independent segregation of homologous chromosomes. Gametes are mentbetweenhomologous
TELOPHASE 2:
andoneofeachpairwillpasstooneofthedaugh-
geneticallydifferentasaresultofdifferentcombinationsofmaternalandpaternal pairs Chromatidsatpoles,new
--
nuclearenvelopesform
tercellswithoneoftheotherpairs.
chromosomes
-- Cytokinesis:Cellsandcyto- Geneticrecombinationbycrossingover
· genetic recombination by crossing over. INTERPHASE 2:
METAPHASE 1: plasmdivide.Therearenow
Whenthechromosomeslineupwithitshomologous
Prometaphase:
Sameasmitosisbutwithno
-- fourcells,eachwithhalfthe
Meiosisisthedivisionofonecelltocreatefourdaughtercells, DNAreplication. numberofchromosomes
pair,thechromatidsofeachpairbecometwisted
--Centriolesareatpoles
aroundeachother.Tensioniscreatedandsome
eachwithhalfthenumberofchromosomesoftheparentcell.It
isrequiredbecausewithsexualreproduction,twogametesfuse -Spindlefibresfromeach
-- partsofthechromatidsbreakoff.Thebrokenpor-
centrioleattachtoonechromo- PROPHASE 2: tionsre-joinwiththechromatidswithitshomologous
togiverisetothenewoffspringandiftheyhadafullsetofchro- someofhomologouspair
mosomes,thenumberofchromosomeswoulddoublewitheach --Chromosomescondense, partner.
Metaphase:
nuclearenvelopedisperses
generation.Inordertomaintainaconstantnumberofchromo- Thecellsproducedbymeiosiswillbegenetically
howeverthereisnocrossing
somesintheadultsofaspecies,thenumberofchromosomes Chromosomepairslineup
-- differentasaresultofthedifferentcombinationsof
over
oneithersideoftheequator
mustbehalvedsomewhereinthelifecycle.Thishalvingis thematernalandpaternalchromosomestheycon-
[independentassortment]
causedbymeiosis.Theprocessissummarisedbelow: tain.
METAPHASE 2:
MEIOSIS 1: Prometaphase:
Homologouschromosomes
--
ANAPHASE 1: --Centriolesareatpoles
pairupwiththeirchromatids --Fibrespullchromosomes -Spindlefibresfromeach
--
andwraparoundeachother. towardseachpole centrioleattachtoonechromo-
Equivalentportionsofthese
-- someofhomologouspair
chromatidsareexchangedin
TELOPHASE 1: Metaphase:
crossingover.
Halfofchromosomesat
-- Chromosomepairslineup
--
eachpole oneithersideoftheequator
[independentassortment]
INTERPHASE 1: Newnuclearenvelopeforms
--
aroundeachhaploidset
--Sameasmitosis
Cytokinesis:Thecellandits
--
--Periodbetweencelldivisions
cytoplasmdivideintotwo
---DNAreplicates

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