Today’s Agenda…  Bellringer: Life Science Multiple Choice Questions  Discuss homework from last night  Notes on Human Genetic Disorders

Human Genetic Disorders Study Pack #13

Genetic Disorders  An abnormal condition that a person inherits through genes or chromosomes  Caused by mutations or changes in a person’s DNA Mutations may occur during meiosis Mutations may be passed on from a parent

Cystic Fibrosis  Produces abnormally thick mucus in the lungs and intestines Difficult to breath Difficult for digestion to occur  Carried on a recessive allele  No cure, only treatments Medicines and physical therapy

Sickle-Cell Disease  Red blood cells have an unusual “sickle” shape Cannot carry as much oxygen as normal blood cells Get stuck in blood vessels  Suffer from lack of oxygen in blood  Experience pain and weakness  The allele is codominant with the normal allele If the person is a hybrid, they will produce both normal and sickle cells  Malaria

Hemophilia  A person’s blood clots very slow or not at all  Person can bleed to death from a minor cut  Caused by recessive allele on X chromosome  Sex-linked disorder Occurs more in males

Down Syndrome  A person’s cells have an extra copy of chromosome 21  Error during meiosis Chromosomes fail to separate properly when sex cells are formed  Distinct physical appearance  Mental retardation

Diagnosing Genetic Disorders  Amniocentesis Doctor removes fluid surround baby and examines the chromosomes from the cells Can determine whether the baby has the correct number of chromosomes and whether it’s a boy or girl

Genetic Counseling  Help couples understand the chances of having a baby with a genetic disorder  Use Punnett squares, pedigrees, karyotypes

Karyotype  A picture of a person’s chromosomes

Pedigrees  Page 319  A visual tool for following a trait through generations of a family  Males are squares, females are circles  Colored circles show where the trait is expressed

Pedigrees  Half colored circles are carriers Heterozygous for the trait but it is not seen in the individual Can pass the trait on to offspring

Homework…  Choose 2 of the genetic disorders we have discussed today and in your OWN words, describe how each is inherited.