Meiosis summary
theproduction ofgametes geneticvariation diversity
diploid 4 haploidcellswith a completesetofchromosomes
createsgeneticdiversityby 1 crossingover
2 independantassortment
prophase1 synapsis
siteon whencrossingferric
recombination ProphaseII sameasmitosisprophase
degenerationofnuclearmembraneenvelope nucleolus
crossing occursbetweennonsisterchromatids
Ema spindlefibresform
genetic synapsis
diversity a metaphase I chromosomealigninmiddleofcellanitasmata
IIE attachto spindles
condensingofchromosomes
nuclearenvelopebreaksdown d
centrioismovetopolesformationofspindlefibers chromosomalsegregation oppositepoles
spindlefiberscontract
metaphase 1
g
tetradslineuponequatorialplate
orderisrandom
telophase chromosomesarriveat poles assinglechromatids
genetic
t I I independentassortment
geneticdiversity a haploidnucleiareformed
centromeresorchromosomesattaintospindles
resultsina nonidenticalhaploiddaughtercens
Ijn
conemomonedad theproductsof meiosis I dueto
I separateintotetrads
are gametes sperm iscrossingover pi
arandomassortmentofhomologous
meres
gift sisterchromatidsremain chromosomesand
spindlefiberscontract
nomologuspairmigrate
topoles
Torana
haploid
formationofnewnuclearmembranes
a
cytokinesisi formationof ageneticallydifferent
daughter cells
eachcellhashalfthenumberof
chromosomesthentheparentcellnad
Haploid
cellsproceed tomeiosisa
nondisjunction failtoseparate inanaphase112
resultsin aneuploidy
with anabnormal
oneextra numberofchromosomes
eg triosoma
opioid normalchromosome
monosomy
missingone chromosome
cells willoften notsurvivemostzygotes
exception triosomy21 downsyndrome
Polyploidy additional homologous setsof chromosomes in a normallydiploidorganismcell triploid3h tetraploidan
common inplants
dueto isextraroundof Dnareplication beforemeiosis
a lackofspindleformation in meiosis prophase
naturalofunnatural
eg seedlesswatermelon triploid
chromosomalrearrangements bigchunks of chromosomes affected
4 types
iscopiedandagain
deletion 3 inversion
partofchromosome partofchromosome partofchromosome
isremoved isflipped
goodorbadcodeis acodeisnowgone
I changed
changesnowgene
isread
4 translocation
recipnica
duringcrossingover
whennonhomologouschromosomescrossover
nonreciprical
new I new
swappingbetweentwo notmutualtranslocation
chromosomes isonechunkfroma chromosomemoves
toanother
new
nonhomologous
severityof rearrangement depends on how wellgeneisreadwhereitoccurred
twoways
1 necrosis themessyway
why cell is damagedbyharmful factors
or starved gingutrients e.g injury toxicchemicals Kemalradiation
now membrane control passage ofionswater
cell will swellup burst
results contents will be leakedthroughholes in membrane intoextracellular enviornment
causesinflamationin tissue
2 apoptosis cleanway
why internalsignals cell is notneeded olddamaged DNA
now cell willdetachfromneighbors
m
cell shrinks and developesmembranouslobes
will breakinto cellfragments with help of activated caspase
Dna in nucleus is hydrolysized cut into fragments
livingcells use phagocytosis todigestdeadcell
lysosomedigests and some is digestingrecycled
plant apoptosis is used as a hypersensitive response to protect themselves from
spreading diseases
partsdigested in vacuoledue tocellwall