Karyotypes and Karyotyping

What Are They? A karyotype is “a visual representation of an individual’s chromosomes arranged in a specific way.” Karyotyping chromosomes involves classifying and organizing them according to the arrangement, number, size, shape, or other characteristics of the chromosomes. These pictures of an individual’s chromosomes allow scientists/doctors to identify characteristics of a person such as gender and genetic disorders, among other things.

How Scientists Read Chromosomes? To "read" a set of human chromosomes, scientists first use three key features to identify their similarities and differences: Size. This is the easiest way to tell two different chromosomes apart. Banding pattern. The size and location of Giemsa bands on chromosomes make each chromosome pair unique. Centromere position. Centromeres are regions in chromosomes that appear as a constriction. They have a special role in the separation of chromosomes into daughter cells during mitosis cell division (mitosis and meiosis). Image taken from: http://learn.genetics.utah.edu/content/begin/traits/scientists/ Using these key features, scientists match up the 23 pairs – one set from the mother and one set from the father.

Typical Female Karyotype 46 Total Chromosomes Image taken from: http://worms.zoology.wisc.edu/zooweb/Phelps/karyotype.html

Typical Male Karyotype 46 Total Chromosomes Image taken from: http://worms.zoology.wisc.edu/zooweb/Phelps/karyotype.html

Monosomy X - Turner Syndrome - Karyotype 45 Total Chromosomes One “X” Chromosome Image taken from: http://worms.zoology.wisc.edu/zooweb/Phelps/karyotype.html

Trisomy 21- Down’s Syndrome - Karyotype 47 Total Chromosomes Three Chromosomes at the 21st Pair Image taken from: http://worms.zoology.wisc.edu/zooweb/Phelps/karyotype.html

XYY Karyotype 47 Total Chromosomes One “X” and Two “Y” Chromosomes Image taken from: http://worms.zoology.wisc.edu/zooweb/Phelps/karyotype.html