Overview Centromere holds sister chromatids together attachment of mitotic spindle fibers allows chromosomes to be pulled to opposite poles during anaphase variations in position metacentric login to view 1 more bullet submetacentric login to view 1 more bullet acrocentric login to view 1 more bullet Nomenclature long = q short = p remember: p = petite translocation = t deletion = del Types of chromosomal alterations Nondisjunction homologous chromatids do not separate properly during meiosis stage of nondisjunction affects gamete production outcome login to view 2 more bullets zygote receiving 3 copies = trisomy zygote receiving 1 copy = monosomy risk greatly ↑ with ↑ in maternal age more common in oogenesis than spermatogenesis Translocation exchange genetic info between nonhomologous chromosomes by breakage and repair balanced login to view 1 more bullet unbalanced login to view 1 more bullet common in cancers types Robertsonian login to view 9 more bullets reciprocal login to view 3 more bullets Inversion type of rearrangement where part of chromosome is inverted in orientation types pericentric login to view 2 more bullets paracentric login to view 1 more bullet Ring chromosomes causes product of two breakage sites on the chromosome and the segment lost circularizes ends of chromosomes join circularizing entire chromosome usually lost during gametogenesis → monosomy Isochromosome replication of one arm of a chromosome with loss of the other p-q → p-p' lethal for autosomes can be observed on sex chromosomes Deletions loss of chromosome segment types terminal login to view 1 more bullet interstitial login to view 1 more bullet