Fruit Flies and Genetics

 

Eye Mutations in Drosophila	Male and Female Drosophila	Normal and Mutant Drosophila
	(click each image for larger version)

Fruit flies (scientific name Drosophila melanogaster) were used as the experimental organism for modern genetics in the early 20th century. They also serve as a great teaching tool to illustrate how physical traits vary and are linked to genes. This is certainly appropriate for a middle school biology curriculum. However, I found that I could explain the basics of DNA, mutations, genes and physical traits to 4th graders (with lots of analogies to beads on a string being a “code” and the code makes small machines that produce physical features (eye color, etc)). DNA, genes, etc may sound daunting, but the basics (if explained simply) are easy enough for kids to understand.

Kids have heard of “mutants”, but it is fun to see a mutant in real life (although your explanation of a mutant may not fully satisfy their vivid imaginations). You can buy a great set of fruit flies to illustrate basic genetics and connections of genes to physical traits from Carolina Biological (see below). For ~$53, you get 9 vials of living fruit flies- 1 vial of normal flies (called “wild type” in genetic lingo) and 8 different mutants (different colored eyes, body color, wing shape, and even one with legs where the antenna should be!). It comes with an excellent teaching manual and also a fly anesthetic to put them to sleep so that you can look at them under the microscope (or if you want them totally knocked out, you can put them in the freezer). There are enough flies to keep a few classes of students happy! You can propagate the Drosophila if you want to do genetic crosses (explained in the teaching manual). Or they will keep for ~7-10 days in the vials (containing food) as shipped from the company.

Fruit flies are perfect for viewing with QX5 by top illumination and ideally with enhancement with a LED flash light (see How to Use QX5 Microscope). First view at 60x and then have a look at 200X where you can see fine details of the compound eye, bristles, and wings.

With the fly kit and QX5, the kids can be scientific detectives. Don’t tell them what the mutations are. Have them view the normal (wild type) flies first- then label the other mutant flies with numbers (1, 2, 3, etc). Have the kids observe and describe what is different for each mutant (this is what the original geneticists did when they discovered the mutant flies in the first place). Write down their observations and share with the class. Fly geneticists get to “name” their mutant flies (and the responsible gene), often giving them descriptive, but fun names. What name would the kids give to their mutant fly? The students can also learn how to identify male and female flies under the microscope.

Fruit Flies: Exploring Mutant Organism Kit Cat# 21-1340 $53.50
https://www2.carolina.com/webapp/wcs/stores/servlet/ProductDisplay?jdeAddressId=&catalogId=10101&storeId=10151&productId=46133&langId=-1&parent_category_rn=&crumbs=n