Simple Inheritance, Pedigrees, & Karyotypes

Pedigrees

•Similar to family trees

•A graphicgraphic representation of genetic inheritance

Pedigree Symbols

Female

Male

Carrier

Female

Affected

Female

Carrier

Male

Affected

Male

Mating

Example of Pedigree

Simple Recessively Inherited Disorders

• Disorder only seen if two recessivetwo 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

•Leads to lipidslipids accumulating in the central central nervous systemnervous system

•Children with disease can can not controlnot control their bodily functions (muscles)

Tay-Sachs Diseaseproblem breaking down lipids; change diet to fix

Phenylketonuria (PKU)

• Body can’t break down an enzyme found in milk; causes nerve damage

• PKU children appear normalappear normal at first• Leads to the build up of the amino

acid: phenylalaninephenylalanine • Can lead to mental retardationmental 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 ChinWidow’s Peak

                                               

Polydactyly – presence of more than 5 fingers and toes

Huntington’s Disease

• Dominantly Inherited

• Neurological disorder that Neurological disorder that causes causes lack of muscular controllack 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: anindividual heterozygous for a specifictrait…(carriesthe trait can pass to theiroffspring)

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

malesXYY Condition

•Down Syndrome – trisomy 21 (extra chromosome on 21st)

Tests to Detect Inherited Disorders

AmniocentiesisUltrasoundFetoscopy

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