Drosophila Simulations Activity © David Faure, InThinking www.biology-inthinking.co.uk  

Learn to identify the fly phenotypes and the male and female flies, click “Find out about”

Hover over each of the flies

Morgan’s first experiment

Make a prediction about the second cross.

Morgan’s White Eyed Male Breeding Experiments

Select white eyed male and wild type female

Carry out a cross

Click “Cross”

F1 offspring flies appear, ready for sorting F1 offspring flies appear, ready for sorting. Drag each fly into a box, top right.

Notice the green tick – if you sort correctly

Final totals / 25 for first cross

Click “cross” again for a second run, note first totals and sort the second set of flies.

Add your results to the chi squared test

Can females be white eyed?

F1 x F1 - cross the heterozygous flies – drag one of each fly to the “New parent” boxes

Click Cross – to see F2 offspring

Sort the flies once again for F2 results.

Choose a white eye male and a heterozygous wild type female, drag them to the “New parents” boxes

Notice the white eyed females

Add your results to the chi squared test

Morgan hypothesized that the eye colour trait was connected to the sex chromosome.

More evidence of gene linkage

Chose a female wild type and a scarlet eyed and ebony body male for the next experiment

Notice the F1 flies are all wild type (but heterozygous)

Choose a male and a female as new parents

Click “Cross”, then sort the F2 flies Click “Cross”, then sort the F2 flies. Notice the low number of recombinants !

A final chi-square test of goodness of fit

Linkage notation

A new type of punnet square for linkage