Modern Genetics

Chp 4 Section 2

Notes

Genetic Disorders- an abnormal condition that a person inherits through genes or chromosomes.

Some genetic disorders are caused by changes in the overall structure or number of chromosomes.

Cystic Fibrosis - this genetic disorder is caused bya recessive allele on one chromosome that had three nitrogen bases deleted from the DNA molecule. It causes abnormally thick mucus that fills the lungs and intestines, which makes it hard to breathe.

Sickle-Cell Disease - affects the hemoglobin, a protein in reb blood cells that carries oxygen. Sickle cell shaped red blood cells clog the blood vessels and cannot carry as much oxygen as normal blood cells. The allele is codominant with normal blood cell alleles.

Two sickle cell alleles = full sickle cell disease

Tne sickle cell allele = half sickle cell half regular blood cells

Hemophilia- disorder in which a person's blood clots very slowly if at all. This is caused by a recessive allele on the X chromosome. Males are more likely to get this then females.

Down Syndrome- causes mental retardation, heart defects are common. This is caused by an extra copy of chromosome 21 being produced.

Doctors use a tool called a karyotype to help diagnose genetic disorders. People with genentic disorders are helped through medical care, education, job training, and other methods.

Karotype - a picture of all the chromosomes in a cell.