cytogenics flash Flashcards
Questions
answers
Mitosis
Converts 2N–>4N–>2N (but with 2 cells). Nondisjunction called mosaicism.
Meiosis
Generate haploid from diploid. Independent assortment. Crossing over.
Crossing over
Meiosis prophase 1: Homologous chromosomes (chromatids) line up and crossover in area known as chiasma. Basis of genetic linkage.
Acrocentric
Stalk
Isochromosome
Abnormal centromere division. Iso-p or iso-q. Loss of genetic material.
Robertsonian translocation
Translocation between acrocentric chromosomes, short acrostalk/ p is lost and the q’s fuse. 45 chromosomes, problem with gamete formation (33% normal)
amniocentesis
0.5% risk, 15-16 weeks gestation, amniotic fluid obtained for cytogenetic study by placing needle in uterus
chorionic villus sampling
0.5% risk, 10-12 weeks, remove cells from placenta (chorion) for cytogenetic study, remove mothers cells
Cordocentesis
1-2% risk, 18 weeks, umbilical blood sampling