Fruit Fly – Genetics Virtual Lab
This is an online lab and can take up to 3 hours to complete. Please schedule your time carefully. You get a much class time as I can schedule into the library or a lab, but it is possible you won’t get ANY class hours. There are multiple steps to this lab and you will need to answer questions for each. I would suggest that you work within your lab notebooks rather than writing the answers online or on this sheet of paper. Think-this lab is about genetics and the process of analysis. On most AP tests there are genetics questions and very often it is over the fruit flies.
Procedure A:
Getting to know the Fruit Fly
Go to google or wikipedia and answer the questions about Fruit Flies:
1. Write out the scientific name for the Fruit Fly correctly:
2. Why do geneticists study the fruit fly?
3. Give a brief description of the life cycle.
Procedure B:
Becoming familiar with the Program
Go to the following website: http://www.sciencecourseware.org/vcise/drosophila/
- This is also linked on my web page.
- Your class code (2011-2012) is: 8049949
- Create a student account write down your information – this will allow you to save and you will be taking an online quiz at the end that will be part of your lab grade
- login: ______________ password: _____________
- Peruse this site for about 5min. click around and see what is available. – Do a random cross and understand the process of analysis.
Do Not click the “back” button in your
browser – this will log you out without the data being stored = start over.
-
The
incubator can only have 2 mating jars at a time, so after the F2
generation click the garbage and clean out the incubator.
Procedure C: Investigation
You will perform several types of crosses to let you become familiar with genetic crosses: For each of these crosses you will complete a F1 and F2 cross, predict and analyze your results.
Note: Alleles in this
demonstration do not indicate dominance or recessive – you will have to analyze
to figure that out.
A) Monohybrid Cross
1) Click to order flies
2) You will choose the following: Wild-type male (allele = +) and a female with LOBE eyes (allele = L) (eye shape then choose lobe). When you choose you will click on the “add to cart” for each.
a) Write a hypothesis with an “If …then” statement referring to one of the traits being dominant and one being recessive and what you would predict the results being if the parent flies were homozygous.
(1) Example to get you started: If one of the traits is dominant and one is recessive then I would predict that the offspring will all have __________________ traits.
b) Write down the Genotypes – These are homozygous flies: _____________________
c) Complete
a
d) Go to shopping cart near the top and make sure you have the flies you would like than click checkout
e) Unpack the box, mate, incubate, and get the flies to the microscope for analysis
f) Click – Sort Flies – Take a look at each pile
g) Click – Send Data to Computer – Click “yes” in confirmation box
h) Click – Analyze Results
i) Look at the results and determine if Sex played a role – if you believe it did not – then check the button to ignore sex
(1) Record the results in your lab notebook
j)
Click on
(1) Enter you hypothesis number for the total flies made – this is just your expected ratio.
(a) Ex. In a cross that is Aa x Aa – you would expect a 3:1 ratio in phenotypes. Remember this is only phenotype ratios – we cannot observe genotypes – that is part of the statistical analysis.
(b) Record your Chi-Squared Test Statistics: _________
(c) Degrees of Freedom: ________________
(d) Level of Significance: __________________
(e) Is your hypothesis accepted based upon Chi-Squared analysis?
(i) Explain answer
(f) Click add to notebook to save in your account
k) Is the wild type trait or the lobed eye trait dominant?
(1) Assign alleles based upon your answer – use the letter L
3) F2 Generation
a) Go back to the laboratory and look at your fly offspring again. While they are under the scope you can choose to use those 2 types in a new mating – do this – cross the offspring to get to the F2 generation.
b) Write a If.. then hypothesis
c) What are the genotypes of this cross? Complete a Punnett square to show your predicted results.
d) Complete d-g above for this cross
e) Describe
the alleles in this experiment – What is the dominant trait? Based upon this information complete a
f) Complete step h from above – Analyze Results and Record & Explain.
B) Dihybrid Cross
1) You will follow the same procedure as in the monohybrid cross. The only difference this time is that you will be choosing body color and eye color on the flies. For the parent generation, select a male with Ebony Body, Purple Eyes and a female with Wild type Eyes and body.
2) Assuming that one fly is homozygous dominant for both traits and the other is homozygous recessive for both traits, what are the expected results?
a) Show
the offspring possibilities through a
Ø
Note
on Allele Symbols and Phenotypes in Dihybrid Crosses : When you observe the table of results on the
website a “+” indicates the wild type
phenotype. If a fly is completely
wild-type there will only be a single “+”.
For example, in this dihybrid cross, a listing of “+” indicates a fly
with wild type body color
3) Mate the two parents and analyze results
a) Determine whether the trait is sex linked – Click or do not click ignore sex.
b) Record results
c) Based on the results in the F1, which alleles are dominant?
d) Identify the genotypes of the parents and offspring from these results.
e) Explain whether your expected results support the observed results. Explain.
4) Complete a F2 generation for this mating.
a) Predict
through a
b) Mate the individuals
c) Record Results – What is the phenotypic ratio?
d) Analyze results – do they meet expectations? Explain
C) Complex Traits
1) For the parent generation, select a male with White Eyes, and a female with wild type eyes (red).
a) Mate and analyze both the F1 and F2 generation.
b) What type of complex trait is White Eye Color?
c) Complete
a
2) For the parent generation, select a female that is wild type and a male that is Eyeless (Eye Color) and Shaven Bristles.
a) Mate and analyze both the F1 and F2 generation
b) What type of complex trait are these 2 traits? Explain how this might happen.
3) For the parent generation, select a female that is wild type and a male that has Stubble Bristles
a) Mate and analyze results
b) Is Stubble Bristles dominant or recessive? What could you cross your offspring with to test this hypothesis? Do so – Explain your results.
4) Complete any combination you would like to help with your understanding. For quiz you need to understand – Monohybrids, dihybrids, sex-linked, linked genes, and test cross.
Procedure D:
Take the Quiz
You will need pencil and paper and some time for thinking – recommend about 30min. to take the quiz.
Make a copy of your results page for your lab & When finished do a “quiz analysis” for any question you got wrong.
Procedure E: E-Report
I activated the ability of the webpage to save a guided electronic report. I have never used this function before. For extra credit, fill in the E-report and submit it.