A picture of chromosomes arranged by size and shape Karyotypes A picture of chromosomes arranged by size and shape

To make a Karyotype Cells are obtained and allowed to grow in a petri dish As cell grow and divide a chemical is applied to stop Mitosis. A Pictures is taken (used to be film now digital) Individual chromosomes are cut and pasted to create diagram

Normal Female Karyotype

Used as a Diagnositic tool to determine if Chromosomes are Missing or Damaged Chromosomes are arranged in Homologous pairs The Largest set comes first Size decreases as pair number increases Last pair Consists of Sex chromosomes Sex chromosomes code for gender and a few other traits All other pairs are called AUTOSOMES.

Normal male Karyotype

Normal Human Karyotype 44 Autosomes or 22 pairs 2 Sex Chromosomes or 1 pair Total 46 Chromosomes or 23 pair Female XX Male XY

Nondisjunction When chromosomes fail to separate during Anaphase, the result is known as nondisjunction Result is having too many or too few chromosomes Too many chromosomes is called POLYPLOIDY or Trisomy Too few chromosomes is called MONOSOMY Disorders resulting from nondisjunction are usually classified by the Number present and the chromosomes number where the problem occurs Often named for the scientist that discovered the problem Some always result in death and are not named

Turner’s Syndrome Monosomy 45XO One sex chromosome missing Automatically girl Always “pre-teen body” Usually never menstrate

Edwards Syndrome Involves 3 copies of 18th chromosome Mental retardation Feeding difficulties, cleft palate Usually die by age 2

Down’s Syndrome Trisomy of 21st Characteristic facial and body shape Can be very low or high functioning but always show mental retardation Often have heart defects

Klienfelter’s Syndrome Trisomy of Sex Chromosome 47XXY Tend to be tall and lean, “lanky” Efeminant—may have breast development or high pitch voice Mentally retarded Usually infertile

Not all are nondisjunction Cri du Chat results from a broken or missing arm on the 5th chromosome Named for the way they cry 1/3 die by age 2

Fragile X Missing or broken arm on sex chromosome. Causes more problems for males who only have one X Have long face and large ears Speech problems and low muscle tone