Simple Inheritance, Pedigrees, & Karyotypes

Pedigrees Similar to family trees graphicA graphic representation of genetic inheritance

Pedigree Symbols Female Male Carrier Female Affected Female Carrier Male Affected Male Mating

Example of Pedigree

Simple Recessively Inherited Disorders two recessiveDisorder only seen if two recessive alleles are inherited.

Cystic Fibrosis Leads to excess amounts of mucus in the digestive and respiratory tract Can be treated

Sickle-Cell Anemia Proteins on blood are changed, thus changing the shape of the blood Abnormal red blood cells they are shaped like a sickle, or half –moon.

Tay-Sachs Disease lipids central nervous systemLeads to lipids accumulating in the central nervous system can not controlChildren with disease can not control their bodily functions (muscles)

Tay-Sachs Disease problem breaking down lipids; change diet to fix

Phenylketonuria (PKU) Body can’t break down an enzyme found in milk; causes nerve damage appear normal PKU children appear normal at first phenylalanineLeads to the build up of the amino acid: phenylalanine mental retardationCan lead to mental retardation

Albinism lacking melanin in skin

Dominantly Inherited Traits Trait or Disorder seen if one dominant allele inherited

Different Dominantly Inherited Traits Free Earlobes Hitchhiker’s Thumb

Cleft Chin Widow’s Peak Polydactyly – presence of more than 5 fingers and toes

Huntington’s Disease Dominantly Inherited Neurological disorder that causes lack of muscular controlNeurological disorder that causes lack of muscular control Onset around age 30

Sex-Linked Traits Traits determined by genes carried on the sex chromosomes (X-chromosome) Ex: colorblindness, hemophilia, muscular dystrophy

Red-Green Color Blindness Common in males People who have red-green color blindness can’t differentiate these two colors

What Colors Do You See?

Hemophilia More common in males Causes a problem with blood clotting

Carrier: an individual heterozygous for a specific trait…(carries the trait can pass to their offspring)

Chromosomal Mutations Mutation: change in the DNA Nondisjunction: chromatids or homologous chromosomes stick together instead of separating…they do not disjoin or come apart Trisomy: has one extra chromosome Monosomy: missing one chromosome

Nondisjunction Turner Syndrome – XO (missing sex chromosome) Klinefelter’s Syndrome XXY males XYY Condition Down Syndrome – trisomy 21 (extra chromosome on 21 st )

Tests to Detect Inherited Disorders Amniocentiesis Ultrasound Fetoscopy

Karyotypes Chart of chromosomes used to diagnosis chromosomal disorders. Chromosomes are arranged in order from the largest to the smallest Also used to determine gender

Example Karyotype