What arekaryotypes? Karyon = kernel, seed, or nucleus the number and appearance of chromosomes in the nucleus of a eukaryotic cell Chromosomes: an organized structure of DNA & protein found in cells 23 pairs (23 from each parent) karyogram--compare pairs, sizes, position of centromere Giemsa dye-staining
What are karyotypes evenused for? (or karyograms of karyotypes) are often Karyotypes used to determine things about a fetus. A blood sample is taken from the mother, and by looking at the karyotype, chromosomal abnormalities can be determined. Observed to see chromosomal and genetic differences between species and within the same species over time. # of chromosomes, the shape/size of chromosomes, and sex of an individual can be observed among other things.
How karyotyping is done. Staining Giemsa dye after cell division Can use almost any cell or tissue1. Blood drawn2. Amniocentesis (to test amniotic fluid)3. Sample grows4. Stained
History Karl Wilhelm von Nägeli first observed chromosomes (via plant cells) in 1842 1920’s-T.S. Painter, XX/XY system for determining sex (not XX/X0) 48 chromosomes 1955/1956, Joe Hin Tijo correctly determined # of chromosomes (46)
T.S. PainterKarl Wilhelm von Nägeli Joe Hin Tijo
Abnormalities/Diseases Turner Syndrome missing or incomplete X chromosome develop as females Down Syndrome error in cell division...extra 21st chromosome impairments in both cognitive ability and physical growth Patau Syndrome trisomy of chromosome occurs in approximately one out of every ten-thousand to sixteen-thousand infants