LAB: Virtual Fruit Fly Genetics (Sex-linked)- DIRECTIONS
Purpose: To investigate the principles of genetics using an online simulation with fruit flies.
Background: Drosophila melanogaster is a fruit fly, a little insect about 3mm long, of the kind that accumulates around spoiled fruit. It is also one of the most valuable of organisms in biological research, particularly in genetics and developmental biology. Drosophila has been used as a model organism for research for almost a century, and today, several thousand scientists are working on many different aspects of the fruit fly.
WHY work with Drosophila? Part of the reason people work on it is historical - so much is already known about it that it is easy to handle and well-understood - and part of it is practical: it's a small animal, with a short life cycle of just two weeks, and is cheap and easy to keep large numbers. Mutant flies, with defects in any of several thousand genes are available, and the entire genome has recently been sequenced.
In today’s virtual lab, you will be focused on a gene located on the X chromosome (the trait is sex-linked) which codes for body color. Wild type body color is dominant to yellow body color
Materials: computer data table to record results of ALL crosses (provided)
directions (these!) *online notebook to record information (part of activity)
pen or pencil *Lab Analysis sheet (provided)
Directions:
1) Getting Started
1) Start computer
2) Open web browser (preferably Mozilla Firefox or Explorer)
3) Launch this website: http://www.sciencecourseware.org/
4) Select the “Virtual Courseware for Inquiry-based Science Education” (top right).
5) Under Life Science, select “Drosophila.”
6) As a “New User,” you need to create a new account, so select “Create New Account.”
7) Follow the directions and prompts to create a new account.
**You will need your class code to do this; record your class code here:
**Record your account information here for future reference:
Username: password:
8) When you finish creating an account, it takes you back to the log-in page. Log in using your newly created account info.
9) You should now see a screen titled “The Lab Bench” with a picture of a science workstation (lab bench, computer, etc.).
10) You are now ready to go on to the Sex-linked Cross!
FOLLOW DIRECTIONS CAREFULLY and be ready to record the results of each cross.
2) Sex-linked Cross 1 …start at “The Lab Bench” screen – see step 9 above
1) Click on Computer to order flies
2) Click on the picture of the fly that says “Order Flies” on left/center of screen
3) Look at screen and read the paragraph titled “Welcome to Fly’s Supplies”
at the bottom of the screen.
4) The default fly is a female, Wild Type. Add this fly to your shopping cart by
clicking on the green shopping cart icon to the right of and below the fly.
5) Once you’ve added the female the male will pop up. On the right tabs
choose “Body Color” (see screenshot). There will be six options.
Select “yellow”. You should see that the picture of the fly on the left now
shows a male with a yellow body. Add this fly to your shopping cart.
6) Your cart is now full with male and female flies. Before checking out click on the shopping cart icon at the top right of the screen.
7) In your shopping cart you should see the following two flies:
1) Female: Wild type
2) Male: Yellow Body
**If you do indeed have these two flies in your shopping cart, click the “Check Out” button. When asked if you are sure you want to purchase these flies, before you check “yes” make sure the box that says “Also add flies to the notebook” is checked. Then complete the purchase by checking “yes.”
8) Back at your lab station, click on the box to unpack the flies you ordered. This will open your box and add both male and female flies to your mating jar. Extra male and female flies will be placed into flasks and stored in the incubator in case you need them for future crosses.
9) Follow the prompt to click on the mating jar to place it in the incubator. Your flies will mate and lay eggs. The eggs will hatch and eventually become adults, the F1 generation.
10) Follow the prompts to remove your mating jar from the incubator, anesthetize the flies and place them under the microscope for viewing. Once they are under the ‘scope, click on “Sort Flies” to separate the flies by both sex and phenotype.
11) Move the cursor over each of the piles to see the sex and phenotype. Click on a pile to view it close up.
12) While viewing under close up you will be able to select two additional options:
1) Add to notebook.
2) Use in new mating.
For each pile do both of these things. On the top right of the page
next to the male and female symbols and the count for each you should
see a small jar icon (added to new mating jar) and a red square icon
(added to notebook). (see the icons in the diagram below, to the left of
the ‘male’ symbol).[1] (“Zoom out” in order to switch piles)
13) Record all F1 offspring data in your paper data table.
14) Before you perform a cross of the F1 generation please go to your “notebook” to make sure that everything has been added. (To see your lab notebook click on the “Notebook” tab on the top left of the screen). REMEMBER TO SAVE THE NOTEBOOK when you are done!!! To return to the activity click on the “Activity” tab in the upper left section.
15) Do the “Checkpoint” and “Check for Understanding” questions for the Parent Sex-linked Cross.
16) Now that you have added both male and female flies from this F1 generation to the new mating jar return to the lab to perform the next cross. (click the “Return to Lab” button)
17) Click on the new mating jar on the lab bench and follow the prompt to put in the incubator. Again, your flies will mate and lay eggs. The eggs will hatch and eventually become adults of the F2 generation.
18) Follow the prompts to remove your mating jar from the incubator, anesthetize the flies and place them under the microscope for viewing. Make sure that you have chosen the correct mating jar, the SECOND cross, not the first. Once they are under the ‘scope, again click on ‘“Sort Flies” to separate the flies by both sex and phenotype.
19) Click on each pile to investigate the sex and phenotype. As you view each group make sure to “Add to Notebook” so you can save your data. Also record these F2 results on your paper data sheet in the appropriate section.
20) Once you have added all of the data to your paper data table as well as your computer lab notebook (and SAVED your notebook data!), return to the lab. (go back to “Activity” and click the “Return to Lab” button)
21) Answer all the “Check for Understanding” questions for the first cross on your paper data sheet.
22) Before proceeding to your next cross, clean up your “lab station” by clicking on the TRASH CAN and follow prompts to perform the clean up – this will clean out the flies from the previous cross and reset your computer. Continue on to the next cross!
**CHECK: in your computer notebook, you should now have data for the 2 crosses (the F1 and F2 generations) described above (they will be recorded as Cross 1 and Cross 2).
3) Sex-Linked Cross 2
1) Back at the lab station, click on Computer to order flies.
2) Click “Order Flies” on left/center of screen.
3) Click on the male fly this time. It should be a Wild Type (+). Add this male fly to your shopping cart.
4) Once you’ve added the male the female will pop up. On the right tabs choose “Body Color”. There will be six options. Select “yellow”. You should see that the picture of the fly on the left now shows a female with a yellow body.
5) Your cart is now full with male and female flies. Before checking out click on the shopping cart icon at the top right of the screen.
6) In your shopping cart you should see the following two flies:
1) Female: Yellow Body
2) Male: Wild Type (+)
**If you do indeed have these two flies in your shopping cart, click the “Check Out” button.
7) To complete this cross follow steps 7-21 from the previous cross.
8) RECORD all F1 and F2 results in your paper data sheet as well as in your online notebook.
9) Clean up your lab station (TRASH CAN).
10) Answer the rest of the questions on the Lab Analysis sheet provided.
[1]