family trees or family pedigrees

• Cystic fibrosis is a recessive inherited disorder
• To have the disease cystic fibrosis, you need to have two cystic fibrosis alleles, represented by lowercase f
• The healthy version of the allele that doesn't cause cystic fibrosis is dominant and represented by a capital F
• If you have the homozygous recessive genotype (two lowercase f's), you will have cystic fibrosis
• If you have the homozygous dominant genotype (two capital F's), you won't have cystic fibrosis
• If you have one cystic fibrosis allele and one healthy dominant allele (genotype: capital F lowercase f), you are a carrier of cystic fibrosis
• In a family pedigree for cystic fibrosis, circles represent females and squares represent males
• Unshaded shapes indicate a person without the condition
• Shaded shapes indicate a person with the condition
• Half-shaded shapes indicate carriers of the condition
• Each new row in the family tree represents a new generation
• Horizontal lines connecting individuals indicate a couple relationship
• Using the family tree, you can determine the genotype of each person:

  <|>Unaffected females have the genotype capital F capital F (homozygous dominant)
• Male carriers have the genotype capital F lowercase f (heterozygous)
• Carriers have the genotype capital F lowercase f (heterozygous)
• Unaffected individuals have the genotype capital F capital F (homozygous dominant)
• Individuals with cystic fibrosis have the genotype lowercase f lowercase f (homozygous recessive)
• In a Punnett square analysis for two carriers (capital F lowercase f), there is a:

  <|>1 in 4 chance of the baby being completely unaffected (capital F capital F)
• 2 in 4 chance of the baby being a carrier (capital F lowercase f)
• 1 in 4 chance of the baby having cystic fibrosis (lowercase f lowercase f)