When parents reproduce, they pass different versions of genes, or
genetic
, for different traits to their
offspring
. The word
dominant allele
is used to describe a trait that is expressed whenever an allele is present. The word
recessive
is used to describe a trait that is only expressed when there is not a
allele
allele present. Because there are different versions of genes, an organaism can be
homozygous
, with two matching alleles, or
, with two different alleles. The offspring of any cross can be described in therm of
, the genetic code of alleles present, or
, the way the trait looks when it is expressed. For example, the
of having freckles can be represented by the
, FF or Ff.