Ouli Maty
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1- both are reciprocal translocation ( 2 non-homologous chrom exchanging pieces), opposite to robertsonian translocation (when two acrocentric chrom lose their p arms and join together at the centromere to form one chrom) .
2-Lets say you have 2 normal nonhomologous chrom A and B and their transloc forms a and b
During Meiosis1, reciprocal transl will have three possible combinations:
-alternate segregation :1 normal cell( 2 nonhomologous AB) and 1 abnormal ( 2 nonhomologous transl chrom ab)
-Adjacent I : 1 off each nonhomologous in a cell(normal chrom+transl chrom Ab or aB)
-Adjacent II: 2 homologous chrom in each cell (normal chrom+transl chrom Aa or Bb )
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| doc4life
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Thanks Maty
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I thought adjacent and not adjacent segregations repate to robertsonian translocation, at least in Kaplan it is written so, when they give example of 14 and 21 chromosomes, that have short arms. What do you think?
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| Ouli Maty
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I think they are saying that after a robertsonian translocation, the translocated chrom can be subject to either an alternate or adjacent segregation, if the chrom itself goes through meiosis.
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| Ouli Maty
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Robertsonian translocation involve two acrocentric chromosomes.
The person who has a Rob transl is OK because he has almost the same number of genes but a little mixed-up (e.g. 1normal 14, 1 normal 21 and 1 big chr 14-21 translocated)
But if his germ cells go through Meiosis.
-If alternate segregation occurs : 1 normal (14, 21) and 1 balanced carrier t(14;21).
-If adjacent segregation occurs, it can give unbalanced cells with 1 monosomy 21 ; 1 monosomy 14; 1 trisomy 14 and 1 trisomy 21( the only one viable).
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