Polydactyly

• What is the inherited disorder discussed in this video?

  Polydactyly II
• What is a characteristic of individuals with polydactyly II?

  They have extra fingers or toes
• What type of allele causes polydactyly II?

  A dominant allele
• Can a person be a carrier of the polydactyly allele?

  No, if you have a dominant allele, you will express the characteristic
• What are the genotypes of a man who is heterozygous for the polydactyly allele and a woman who is homozygous for the normal allele?

  Man: Pp, Woman: pp
• What are the expected genotypes and phenotypes of the offspring from the cross between a heterozygous man and a homozygous normal woman?

  • Genotypes: 50% heterozygous (Pp), 50% homozygous normal (pp)
  • Phenotypes: 50% with polydactyly, 50% unaffected
  • Ratio: 1:1 (polydactyly to unaffected)
• What does the ratio of 1:1 in the offspring indicate?

  It indicates equal probabilities of having polydactyly or being unaffected
• What is embryo screening?

  Testing embryos for alleles of inherited disorders
• What happens to embryos that do not have defective alleles during embryo screening?

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

  Some healthy embryos are destroyed
• What is a potential future application of embryo screening that raises ethical concerns?

  Producing offspring with desirable features
• What is gene therapy?

  A method to correct faulty alleles to treat inherited disorders
• Is gene therapy currently a standard treatment for inherited disorders?

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

  • Expensive process
  • Ethical concerns about destroying healthy embryos
  • Potential for screening for desirable traits
• Where can students find more questions on polydactyly and embryo screening?

  In the revision workbook