Mathematics and Society - OS X Lion Server

a mode! 50r!nhQfitanc8/(, ,For this activity students will need at least 20 centimetre squares from coloredplastic and 20 centimetre squares from clear plastic. Put each set into an envelope orsmall bag.The colored squares (let's use red) can represent the dominant color (R) of animaginary animal and the clear squares represent the recessive color (1'). To performa cross have a student draw a square from each bag. Record the allele combination.Put the two squares together and look towards a light source. Record the color seen.Repeat the drawing several times. The results should always be a Rr genotype and ared phenotype. R RThe grid looks like this. Students shouldrealize that this cross between a pure dominantRrtrait and a pure recessive trait yields 100%hybrid dominant traits.RY'To continue place an equal number of red and clear squares in each bag. This (simulates the allele combination for hybrid red color. Have students draw a squarefrom each bag and record the combination and color. By repeating the procedure manytimes the results should approximate those shown in the following grid.RrR RR RY'Y' Rr rrPHENOTYPE R.ATIO OF 3 REDS TO I W~nE.GENOTYPE R.ATIO OF I PURE: RED TO 2. l-\YBRIDRED TO I PURE CLEAR.168A similar type of simulation can be done using two coins and letting heads (H)represent the dominant color and tails (h) represent the recessive color.probable outcomes of tossing two coins is t HH, ~ Hh and t hh which agrees with theallele combination for a trait.IDEA FROM:Modern Life Science, by F. L. Fitzpatrick and J. W. Hole,Copyright © 1970 by Holt, Rinehart and Winston, PublishersPermission to use granted by Holt, Rinehart and Winston, PublishersThec·