Overview examine chromosomal structure Process mitotic cells in metaphase selected from actively dividing cell population white cells, bone marrow, placenta, amnion when chromosomes are most condensed chromosomes are stained with or without G-banding G-banding involves partial digestion with trypsin leaves alternating dark and white bands staining with Giemsa or other stains which have affinity for DNA spectral karyotyping 5 different fluorescent probes are added special digital image processing colors each chromosomes differently chromosomes are ordered, numbered based on unique properties of all 23 chromosomes Clinical use can analyze whether a gross chromosomal abnormality exists ex.) trisomy, monosomy used commonly for prenatal diagnosis via chorionic or amniotic sampling spectral karyotyping can also diagnose translocations, inversions, or deletions of specific chromosomal segments if the change is large enough