Inherited disorders and Sex determination

• Gene

  Small section of DNA on a chromosome, codes for a particular sequence of amino acids to make a specific protein
• Polydactyly


  Extra fingers or toes, caused by a dominant allele
• Cystic Fibrosis

  Disorder of cell membranes, caused by a recessive allele
• Embryonic screening Advantages

  • Can find out if the Embryo has an Inherited Disorder
  • Can prepare for the baby (Early Treatment)
  • Can decide whether to continue with the Pregnancy
  • Fewer people with Inherited Disorders overtime
• Embryonic Screening Disadvantages

  • Implies people with genetic disorders are undesirable
  • Future screening for other traits
• Sex determination

  • Ordinary human body cells contain 23 pairs of chromosomes.
  • 22 pairs control characteristics only, but one of the pairs carries the genes that determine sex.
  • In females the sex chromosomes are the same (XX).
  • In males the chromosomes are different (XY).
• What is an Allele?

  Different versions of a Gene
• What is Genotype?

  • The Collection of Alleles a person has
• What is Phenotype?

  • Visual Characteristics a person gets from their Genotype
  • e.g. Black Hair, Brown Eyes
• What is Homozygous?

  • Two Alleles that are the same
• What is Heterozygous?

  • Two Alleles that are different