Mutations

Chromosomal Mutations

• Nondisjunction– Result of errors in Meiosis– Results in gametes with missing or extra

chromosomes– Examples: Downs Syndrome, Turner’s

Syndrome, Kleinfelters Syndrome

Nondisjunction

Chromosomal Mutations

• Broken chromosomes– Deletions = section of chromosome is lost

during cell division – Inversion = broken section of chromosome is

reversed and reattached to the chromosome

Chromosomal Mutations • Duplication = fragment attaches to its

homologous chromosome

• Translocation = fragment attaches onto a nonhomologous chromosome

Sources of Genetic Variation

• Independent assortment• Crossing over• Mutations

Types of Mutations in Genes• Point mutation–Mutation in a single base pair

Types of Mutations in Genes• Frame shift mutation–Alters the entire amino acid sequence

Genetic Disorders

• Single gene defect– Mutation in an allele (point mutation or frame

shift)– Examples: cystic fibrosis, sickle cell disease,

Huntington’s

• Treatments– Modify lifestyle– Drug therapy– Gene therapy

Genetic Disorder Diagnosis • Fetal Screening–Amniocentesis –Ultrasound

• Newborn Screening• Blood tests can screen for a few disorders

(PKU)

• Gene Testing•DNA tested to see if carrying a

specific gene.

Pedigree• Allows us to track traits and/or mutations

among related individuals over many generations