Drosophila Research: Project I
Group projects are a collaborative effort done mostly outside of regularly scheduled class time, though students may have time during the laboratory period
to make observations and talk together as a group. It is important that every student participate equally in all aspects of the experiment. Your team members
will also grade your participation and willingness to do the work ! Students at a group table must learn to maintain stocks, set up experiments, obtain
necessary virgin females. Figuring out the correct timing for obtaining virgin females is very important. Females newly hatched will mate with males in the
same jar 8-10 hours after hatching. Please understand the difference between keeping viable stock cultures and then setting up the appropriate mating !!!
The Punnett squares representative of each cross must be understood as the expected results. The correct symbols for animal genetics must be used. The
abnormality names the gene, lower case letter signifies recessive, and a “ + “ is used to signify the dominant allele. students had to learn to maintain stocks,
set up experiments, obtain necessary virgin females. Figuring out the correct timing for obtaining virgin females is very important. Females newly hatched
will mate with males in the same jar 8-10 hours after hatching. BUT this year Your team will do a simple Mendelian Monohybrid cross….. YOU will not do
Morgan’s cross……I will give you virgin females of white eye for RECIPROCAL of MORGAN .
After you set up the Parental for Reciprocal of Morgan…. you will have to get rid of parents after 10 days….then wait for F1 flies….and put a bunch ( 6-10 ) into
a new clean vial. That will be your F1 X F1 cross. Again after 9-10 days get rid of the F1 flies……AS the F2 hatch we will count the F2 flies…and hope to see the
1:1 ratio…really 1:1:1:1…….then we will do a Chi Square test to see how “good” our data fits the hypothesis.
Mendel’ results vs. Sex Linkage discovered by Morgan
ALL TEAMS DO THIS:
Typical Mendelian Monohybrid cross
P Female or male recessive X wild type
F1 F1 X F1
F2 3:1 ratio ….. always…..why??
PROBABLY NOT DOING THIS CROSS
Sex –Linked Genes = Exception to Mendel
P Female wild type X Male white eye
F1 F1 X F1
F2 3 wild type red eye: 1 white eye
ALL TEAMS DO THIS:
Reciprocal Cross of Sex linked genes:
P Female white eye X Male wild type
F1 F1 X F1 …….interesting !!!
F2 1: 1 ratio wild type red eyes to white eyes
Actually 1:1:1:1 red eye female :red eye male: with eye female: white eye male
EQUAL CHANCE FOR ALL 4….VERY different from Mendelian genetics where it does not matter what is the sex of the parents in the original Parental cross
Steps in designing and implementing your Group Research Project
• Decide on a research problem: Transmission Genetics ( SEX Linkage in Humans…as explained by Fruit fly crosses !!!)
• Collect and read relevant articles on Mendelian Genetics and compare and contrast with other form of inheritance which you have studied. Include
information on your assigned human gene located on the X Chromosome. Give background and context. Your Paper is about a human sexlonked disease…
you are using fruit flies to demonstrate the transmission of genes in a Mendelian Monohybrid…and showing how final results can differ from Mendel in Sex
linkage…as shown by Morgan !
• Research Paper is always divided into:
▪ Materials and Methods
▪ Results ( including both final results and Chi Square analysis)
o This is a short Paper…..and more instructions will be given…..this will help you to write a “Research Paper” NOT A LAB REPORT !!!