Sex Chromosomes, Genetic Diagrams and Inherited Disorders

• What is the probability that offspring will have the XX combination of sex chromosomes

  50%
• What are alleles?

  Alleles are alternative forms of a gene that occupy the same position on a chromosome and determine specific traits.
• What does it mean if someone is heterozygous for a gene?

  Two different alleles for a gene.

  E.g. Cc or Dd
• What is the chance of a child being born with polydactyly if one parent had a single dominant allele for the gene that controls it?

  50%
• Give two arguments for and two arguments against screening embryos for genetic disorders?

  For: Early detection, informed decision-making. Against: Ethical concerns, potential for discrimination.