Inheritance and Punnet squares

• what is a homozygote

  individual with 2 identical alleles (BB or bb)
• what is a heterozygote

  individual with different alleles (Bb)
• what is a genotype

  alleles present or genetic makeup (Bb or bb)
• what is a phenotype

  physical appearance of characteristic
• how do you construct a punnet square

  1. determine parental genotypes (Aa, Bb, Dd)
  2. split alleles for each parent and add to punnet square around the edges
  3. work out possible genetic combinations
• fill in the punnet square

  parent 1- Aa

  parent 2- Aa

  A) AA

  B) Aa

  C) Aa

  D) aa

  
• what is a dominant allele

  only one (out of the two alleles) is needed for it to be expressed and for the corresponding phenotype to be observed
• what is a recessive allele

  two copies of the allele are needed for it to be expressed and for the phenotype to be observed
• what is a gene

  short section of DNA that codes for protein and therefore contributes to a characteristic
• what is an allele

  different forms of an allele
• what are uppercase letters used for in punnett squares

  dominant characteristics
• what are lowercase letters used for in punnett squares

  recessive alleles