Study Notes on Cytogenetics

Essay by veryfat November 2004

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karyotype- chromosomes of a person that's photographed at metaphase and arranged in order

autosomes- chromosomes 1-22; not sex chromosomes

sex chromosomes- chromosomes that determine the sex; X and Y chromosomes

translocation- chromosomal abnormality in which a chromosomal segment is transferred to a nonhomologous chromosome

duplication- chromosomal abnormality in which a chromosomal segment is duplicated and present in more than one copy within the chromosome

deletion- chromosomal abnormality in which a chromosomal segment is missing

amniocentesis- method of sampling the fluid surrounding in the fetus by inserting a hollow needle and collecting fluid to diagnose a fetal genetic and developmental disorders; performed in 16th week of pregnancy

chorionic villus sampling- method of sampling fetal chorionic cells by inserting catheter through vagina or abdominal wall into uterus to diagnose biochemical and cytogenetic defects in embryo; performed in 8th and 9th week of pregnancy

polyploidy- chromosomal number that is multiple of normal haploid chromosomal set

aneuploidy- chromosomal number that is not exact multiple of normal haploid chromosomal set

monosomy- one member of chromosomal pair is missing; 2n-1

trisomy- an extra member of chromosomal pair is present; 2n+1

dispermy- fertilization of egg by two sperms, making a triploid zygote

triploidy- condition in which there are three copies of all autosomes and sex chromosomes

tetraploidy- condition in which there are four copies of all autosomes and sex chromosomes

non-disjunction- failure of homologous chromosomes to separate during mitosis or meiosis

Trisomy 13- presence of an extra copy of chromosome 13 (47, +13)

Trisomy 18- presence of an extra copy of chromosome 18 (47, +18)

Trisomy 21- presence of an extra copy of chromosome 21 (47, +21)

Turner syndrome- monosomy of X chromosome (45, X)

Klinefelter syndrome- aneuploidy of sex chromosomes involving XXY condition (47, XXY)

XYY karyotype- Jacob's syndrome; aneuploidy of sex chromosomes involving...