Genetic Disorders and Karyotypes

Review Question

• How many chromosomes are in a normal human?

• 46 or 23 Pairs

Autosomes and Sex Chromosomes

• Every normal person has 44 chromosomes that code for all of the functions and characteristic of the body.

• These are called AUTOSOMES.

• The remaining two chromosomes are SEX CHROMOSOMES

• Sex chromosomes can be either X or Y

• Male: XY Female: XX

Review Question

• What type of cell division do sex cells go through?

• Meiosis

Genetic Disorders

• Sometimes chromosomes do not separate correctly during meiosis. This is called NONDISJUNCTION.

• Nondisjunction can cause abnormalities within the pairs of chromosomes• Sometimes there are too few or too many chromosomes.

Down Syndrome

• Caused by a trisomy on the 21st pair of chromosomes.

• Characteristics include:• Wide set eyes

• Small facial features

• Some degree of cognitive impairment

• Average life span is around 60 years.

Klinefelter Syndrome

• Caused by extra X chromosome in males. • XXY instead of XY

• Characteristics:• Tall with long limbs

• Infertility

• May grow breast tissue

• Many times symptoms are mild and go unnoticed

Turner Syndrome

• Caused by a single X chromosome in females.• X instead of XX

• Characteristics:• Short stature

• Skeletal defects

• Infertility

• Heart defects

• Kidney problems

Karyotypes

• A karyotype is a diagram that shows a cell’s chromosomes arranged in order from smallest to largest.

• Made from a photo taken through a microscope.

• A great tool to analyze the chromosomal make up of an individual.

Normal Male Karyotype

Normal Female Karyotype

What is this disorder? Down Syndrome

What is this disorder? Turner Syndrome

What is this disorder?: Klinefelter Syndrome