Experiments 5: Do distinct factors interact?

Up to now we have been following at only a one character at a time in our crosses. This kind of cross is known as a monohybrid cross.

We can extend our analysis to multiple characters (dihybrid for two traits, trihybrid for three, etc).  This provides information about the how factors behave with respect to one another, although it quickly becomes quite complicated.

We can look at the behavior of five characteristics:

• plant size (short or tall)
• flower color (white or purple)
• flower position (axial or terminal)
• pod shape (smooth or constricted)
• twisted (straight or twisted)

Experiment 5 Directions:  Design a set of crosses to determine if the inheritance of these five traits are independent of one another.  One way to do this efficiently is to use dihybrid and trihybrid crosses:  make a prediction of the frequency of offspring in an F2 trihybrid cross and compare against what you observe.  How many trihybrid crosses are needed to determine all five traits are inherited independently of one another?  Record your data and defend your conclusions. 

• Use the javaGenetics™ (not currently working) applet for your studies.