Cystic Fibrosis

• What inherited disorder is discussed in the video?

  Cystic fibrosis
• What are alleles?

  Different versions of a gene
• What is the difference between dominant and recessive alleles?

  Dominant alleles are expressed with one copy
• How is cystic fibrosis controlled genetically?

  By a single gene with two alleles
• How many copies of the defective allele must a person have to have cystic fibrosis?

  Two copies of the defective allele
• What do we call a person with one defective allele and one normal allele?

  A carrier of the cystic fibrosis allele
• What is the first step in constructing a Punnett square?

  Write down the genotypes of the gametes
• What should you remember about the numbers in genetic crosses?

  They are probabilities, not certainties