Part 4: Making your first generation (F1) cross
To make this cross:
1.† Be certain,
by visual inspection, that your females are virgin.† Look for the presence of larvae in the food.† You may need to use the stereomicroscope for
Part 5: Examining the F1 Generation
Construct a data table in your journal.† The table needs to include:
1) The parents you crossed
Also in your data table, write how long it will take for larvae to become adults. Two days after this you can begin taking data.
Below is one type of data table. Feel free to use it as a template or construct your own. You will need a separate data table for each cross you do. Put this in your journal Remember to add a title to your table!
When you have a vial with 30 or more adults,
anesthetize them, count the flies by sex and phenotype, and record in
your data table.
Part 6: Making the F2 Cross
After your F1ís have eclosed (adults emerge), wait 2-3 days before making a F2 cross. Using the procedure from above, obtain 5 virgins from each vial and cross them with 5 males from the same vial.† What should your procedure be if you have several different flies with different phenotypes? Complete the cross as before, recording your information in your journal.† Examine the F2 generation as you did with the F1.
Use your data to construct ratios for the F1 and F2 phenotypes.†
1. Answer these questions in your journal.
2.† Create a poster for the rest of the class to see your results. †The poster must include pictures or drawings of
1. Male and female P1 flies
showing their different phenotypes and genotypes
a drawing of your poster in your journal.
Part 8: Self assessment
At the end of this lesson your journal should contain;
1.† A completed
table of contents
At the end of this lesson you should be able to:
use and understand new vocabulary words
The University of Arizona
Department of Biochemistry and Molecular Biophysics
General Biology Program for Secondary Teachers