BI226 2009 Section 1: Variations on Mendel’s theme
• Alleles are inherited according to Mendelian principles, but the traits encoded by some
alleles do not appear in typical Mendelian ratios because of variations in the ways in which
genes are expressed phenotypically.
• Different types of gene expression and gene interaction can be detected phenotypically.
• DNA markers are inherited like alleles that affect physical characteristics, but are free of
many of the limitations for genetic analysis that physical traits may have.