Genetics and Mutation Note s
__________________is based on predictable patterns of inheritance. Understanding genetics
depends on understanding these patterns, which are based on possible combinations of
gametes. ___________________ ______________ provide a way to det ermine these
combinations. Thus, it is possible to predict offspring traits.
MONOHYBRI D CROSS ES
In Mendelian genetics, each trait has two alleles. In__________________ _______________,
one trait is involved. In a monohybrid cross, each parent contributes two alleles, producing four
possible combinations for the one trait.
____________________ _________________ involve two traits. A dihybrid cross involves two
alleles per trait for two traits, for a total of four alleles. The gamete combinations predict which
offspring (F2 generation) can be produced from these F1 parents. The ________________
__________________(relative count of trait combinations) can now be determined. It is
recommended that phenotypes be written in each square when working a Punnett square
problem. Remember that phenotype is determined by genotype. Therefore, the phenotypes can
be det ermined by the alleles in eac h offspring square: an uppercase letter represents a dominant
allele. Any offspring with one uppercase letter for a particular trait will have
that trait.