Absolutely not! Although the R and S are of the same type style (Old English), their values for word formation are different. Just as the word ROSE can be written with different mixes of letter styles, as long as the letters are properly placed, there is no doubt as to the meaning. Letters cannot be substituted for each other although different styles of the same letter can. Similar situations prevail with genes and their alleles. Genes are responsible for a particular product. Their variable expressions however are interchangeable. See examples at the right. Flip to the next card for more defined terms or use the PREV. button to go to the previous card. Click on the MULTIPLE ALLELES button and see how they are inherited.