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Dr. Karen Harrison
Department of Pathology &
Molecular MedicineQueen’s University
!asics of "ytogenetics#Mitosis and Meiosis $utorial
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%'ectives#( Descrie the process of somatic cell
division ) mitosis ) and the
conseuences of any errors
( Descrie the process of germ cell
division ) meiosis ) and the
conseuences of any errors
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"hromosome *unction
( "arry genetic information in a defined
structure
( ensure somatic cell division +mitosis,
⇒complete genetic complement
( ensure gamete formation +meiosis,
⇒uniue set of parental genes
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-hat is Mitosis
( /omatic cell division consisting of
nuclear division and cyto0inesis
( /ingle cell divides to produce t1o
identical daughter cells
• crucial for gro1th and development( human 2ygote 3 4 cell
( mature adult 3 4 5 46 47 cells
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Mitosis
*rom $hompson & $hompson 8th 9d +:664,
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"onseuences of Mitosis
( ;ormal mitosis#
< %ne cell⇒: progeny cells 1ith identical
genetic content < crucial for gro1th and development
( Mitotic errors#
< daughter cells do not have identical geneticcontent 3 =mosaicism=
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-hat is Mosaicism
( >n individual 1ith : different cell lines
derived from a single 2ygote
= 47
= 46
lethal
=45
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Mitosis and ;on)dis'unction
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-hat is Meiosis
( ?erm cell division
< gametogenesis
( Key event that alternates haploid and
diploid phases of human life cycle
< production of haploid germ cells
( : successive cell divisions 1ithout
intervening D;> replication
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"onseuences of Meiosis#
reproduction and species maintenance
( eduction of chromosome numer +78
⇒:A,
( random segregation of alleles
( random assortment of homologous
chromosomes
( increase genetic variation
+recomination,
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( "omparison
of mitosisand meiosis
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>normalities Bn Meiosis#( Meiotic non)dis'unction#
< meiosis B
→ aneuploidy
< meiosis BB
*
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"auses of Meiotic ;on)
dis'unction( Primary "ause#
>ging effect on primary oocyte
< Cate maternal age +CM>, ⇒ predisposes to
non)dis'unction
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"onseuence of ;on)
dis'unction( >neuploidy 3 any chromosome numer
that is not the eact multiple of the
haploid numer +:A, < trisomy +:4E 4AE 4F,
< monosomy +5,
( Meiotic ;D ) not mosaic( Mitotic ;D ) mosaic
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/ome Useful -esites
( 111.iology.ari2ona.eduGcellioG
tutorialsGcellcycleGcellsA.html
( http#GG111.accessecellence.orgG>!G
??Gcomparison.html
( http#GG111.sci.sdsu.eduGmultimediaGmitosisGmitosist4.html
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Questions
Dr. Karen Harrison
( K?H 5776I