DNA & Fruit Fly Genetics
Worksheet
Type in the blanks and submit this worksheet through the assignment tab in iCollege. Paste pictures below the words “Insert Picture Below.” Resize pictures as needed to fit at least two pictures per page.)
Experiment:
You have completed the isolation of DNA from onion cells.
Questions:
Insert a picture of the DNA “gelatinous sludge” below.
Which of the chemicals in the process removes the plasma & nuclear membranes?
Which of the chemicals in the process removes the proteins from the DNA?
Experiment #1: Segregation of Eye Color (Red vs Sepia)
Experiment
Using the fruit fly simulator program, you have mated flies of two different eye colors.
Questions
What were the phenotypes and numbers of your first offspring (F1)? Which parents (P) did they look like?
You have mated fruit flies with different alleles for eye color. Which allele was dominant? What is the definition of dominant?
Your next mating will take males and females from this generation (F1) and mate them together to make the next generation (F2). Write a simple hypothesis for what you think the F2 children will look like. For example, will there be a difference between males and females?
Experiment #2: Segregation of Wings and Apterous
Experiment
Here you have mated flies with wings and no wings (apterous).
Questions
What were the phenotypes and numbers of your second generation offspring (F2)? Calculate a proportion for each by dividing the number of flies with the phenotype by the total number of flies.
Create Punnett Squares for the F1 and the F2 offspring.
F1 offspring F2 offspring
Experiment #3: Independent Assortment of Eye and Wing
Experiment
In this experiment, you have mated wild type winged females and sepia eyed males with no wings. Remember to use the “Ignore Sex” button.
Questions
What were the phenotypes and numbers of your first generation offspring (F1)? Calculate a proportion for each by dividing the number of flies with the phenotype by the total number of flies.
What were the phenotypes and numbers of your second generation offspring (F2)? Calculate a proportion for each by dividing the number of flies with the phenotype by the total number of flies.
Now recalculate the proportion of eye phenotypes alone (ignoring wings). Do the same for wing phenotypes alone (ignoring eyes).
Mendel’s Law of Independent Assortment allows us to consider each trait individually. Create a Punnett Square for the F2 offspring eyes (A & a) and another one for their wings (B & b). Do you see the ratios you expected based on counting eyes alone or wings alone?
F1 Offspring F2 Offspring
For each of the four eye/wing phenotype combinations you saw at the beginning, multiply the proportion for that eye phenotype by the proportion for that wing phenotype. Do you get approximately the same proportions you counted in the beginning of this cross?
