Polydactyly

• What is the inherited disorder discussed in this video?

  Polydactyly II
• What is a characteristic of polydactyly II?

  Extra fingers or toes
• What type of allele causes polydactyly II?

  Dominant allele
• Can a person be a carrier of the polydactyly allele?

  No, they will express the trait
• What are the genotypes of a heterozygous man and a homozygous normal woman in a cross?

  Man: heterozygous, Woman: homozygous normal
• What is the expected ratio of offspring in the cross between a heterozygous man and a homozygous normal woman?

  1:1 polydactyly to unaffected
• What percentage of the offspring will have polydactyly in this cross?

  50%
• What is embryo screening used for?

  To test embryos for inherited disorders
• What happens to embryos that do not have defective alleles?

  They are implanted into the woman
• What is a major ethical concern regarding embryo screening?

  Destruction of healthy embryos
• What is a potential future application of embryo screening?

  Producing offspring with desirable features
• What is gene therapy?

  Correcting faulty alleles to treat disorders
• Is gene therapy currently widely used?

  No, it is still experimental
• What are the issues surrounding embryo screening?

  • Expensive process
  • Ethical concerns about embryo destruction
  • Potential for selecting desirable traits
• What are the characteristics of polydactyly II and cystic fibrosis?

  • Polydactyly II: Extra fingers or toes, dominant allele
  • Cystic fibrosis: Recessive disorder affecting lungs
• What are the steps involved in using a Punnett square for genetic crosses?

  1. Identify parent genotypes
  2. Set up the Punnett square
  3. Fill in the square with possible offspring genotypes
  4. Calculate ratios and percentages