Using seeds of Wisconsin Fast Plants, Brassica rapa, we’ll study the inheritance of two phenotypes, stem color and stem height. These phenotypes can be observed in the seedling stage. You will be provided with seeds from the F1 and F2 generations. You will germinate the seeds, make predictions and analyze the data you collect.
THE GENES:
Stem Length Gene – codes for a protein called gibberellic acid that acts as a hormone that stimulates growth in the length of the stem.
G = normal stem length
g = short stem legth
Stem Color Gene – codes for a protein called anthocyanin that functions as a pigment
A = purple / red stem in sprouting plant*
a = non-purple stem in sprouting plant
*the stem may turn green in older plants
THE CROSSES:
Cross 1: P1 X P2 (parent 1 crossed with parent 2) to create F1 seedlings
P1 seeds have the genotype aaGG.
P2 seeds have the genotype AAgg
Cross 2: F1 X F1 to create F2 seedlings
PROBLEM QUESTION: does the predicted phenotypic ratio for the offspring (the seeds) of the dihybrid cross matches the actual ratio observed in the germinating seeds for the F1 and F2 generation.
In order to complete the task, you must create a typed final draft quality report in which you:
Write the problem question
Write a hypothesis predicting what the phenotypic outcome of the cross will be, using a Punnett Square or the rule of multiplication to explain your prediction. Note: you'll have a hypothesis for each the F1 and F2 generation. Be sure to include a key to the notation used to represent the genes and alleles.
Record and analyze the phenotypes of your F1 and F2 seedlings (following IB standards for data collection) to determine whether your F1 and F2 results are significantly different from the theoretically expected results. It's two separate analysis; one for the F1 seeds and another for the F2 seeds. Note: not all seeds will have germinated, so there will be some seeds for which data collection is not possible.
Present results graphically (following IB standards)
Write a conclusion statement (full IB conclusion is not required).
Lab report due: Friday, 06 May, 2011
