Polydactyly

• What is the inherited disorder discussed in the 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
• If a person has one copy of the polydactyly allele and one copy of the normal allele, what will their phenotype be?

  They will have polydactyly
• What is the genotype of a man who is heterozygous for the polydactyly allele?

  One copy of the polydactyly allele and one copy of the normal allele
• What is the genotype of a woman who is homozygous for the normal allele?

  Two copies of the normal allele
• What are the expected genotypes and phenotypes of the offspring from a cross between a heterozygous man and a homozygous normal woman?

  • 50% heterozygous for polydactyly (will have polydactyly)
  • 50% homozygous normal (unaffected by polydactyly)
  • Ratio: 1:1 polydactyly to unaffected
• What does it mean that the ratio of offspring is just probabilities?

  It means that all offspring could potentially have polydactyly or none could
• What is embryo screening used for?

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

  Screening for desirable features like height or intelligence
• 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 should students expect to find in their revision workbook regarding polydactyly and embryo screening?

  • Plenty of questions on polydactyly
  • Questions on embryo screening