Chromosomes and reproduction - chromosomal abnormalities
3 important questions on Chromosomes and reproduction - chromosomal abnormalities
T 3 hetypes of numerical abnormalities?
- polyploidy -> possessing more than two complete stets of chromosomes -> 3n, 4n, 5n -> caused by polyspermic fertilizations or retention of second polar body.
- haploidy -> n -> in general non compatible with post-natal life
aneuploidy -> possessing any chromosomes number that is not an exact multiple of the haploid number of chromosomes -> 2n-1 (monosomy), 2n+1 (trisomy)
- most of the time arise from oocyte meiotic devisions after fertillisation.
- turner syndroom is the only monosomy compatible with live (45, X0), girls will not enter puberty becauseteh mis a X chromsome
- aneuploidy can also occur in tumors.
The orgins of trploidy (3N)
- Retention of second polar body, which lead to 3 nuclei
- Di-spemic fertilization --> 3
pronuclei and allot of centrosomes
Structural chromosome abnormalities? (8)
- Deletion
- duplication
- iversion
- insertion
- translocation
- reciprocal translocation
- nonreciprocal translocation
- robertsonian transloaction
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