Genetics Lab: Crossing Fruit Flies

Back to Biology

Step 1 of 9

A family mystery

About this model

This lab models two real fruit fly (Drosophila melanogaster) genes. Vestigial wings and sepia eyes are both recessive, and the two genes are on different chromosomes, so they are inherited independently.

Every offspring gets one random allele from each parent, like flipping a coin for each parent. That is why real counts only come close to the Punnett square prediction.

Real flies are more complicated. Some genes sit on the X chromosome, and temperature can change how vestigial wings look. This lab leaves those out.

About this activity

Breed fruit flies to follow wing shape and eye color. Build Punnett squares, compare predictions with offspring counts, and use a test cross to find a hidden genotype.

Related lessons

Instructions

Breed fruit flies to see how two traits are passed from parents to offspring: wing shape and eye color.

Work through the numbered steps. Tap or click to choose answers. In the Punnett square, drag an allele tile into a box, or tap a tile and then tap a box. With a keyboard, press Enter on a tile and then Enter on a box.

You can go back and redo any step. Nothing is graded, and nothing is saved or sent. Reloading the page or pressing Start over clears your work.

When you finish, open Copy my data. It copies your crosses and counts so you can paste them into your worksheet or document. Write your answers there.

Start over?

This clears every step on this page. You will get the same mystery flies again.