Punnett Squares

• There are different forms of genes called alleles, one inherited from the father and one from the mother.
• A capital letter is used to indicate the dominant gene.
• A lower case letter is used to indicate the recessive gene.
• The Punnett square is a diagram that shows the possible combinations of alleles that can be produced in a particular genetic cross.
• The recessive gene will not show if the dominant gene is present.

  The recessive gene can be passed onto offspring.
• Brown (B) is dominant, blue (b) is recessive.

  
• Homozygous

  Term used to refer to an organism that has two identical alleles for a particular trait.

  e.g. (TT or tt)
• Heterozygous

  Term used to refer to an organism that has two different alleles for the same trait.

  e.g. (Rr)