Lionfish Genetics Instructor Guide
This lesson is designed to cover high school biology standard B-4.6 Predict inherited traits by
using the principles of Mendelian genetics (including segregation, independent
assortment, and dominance). It takes approximately 90 minutes to complete.
In order to give students a variety of parental genotypes, I set up 30 strips each with a different
sex and genotype (see picture below).
I helped the class through the process of segregation using independent assortment to find the
gametes they could produce. I explained it this way:
1. Assign each letter of your genotype a number 1-6
R r S s M m
1 2 3 4 5 6
2. Find all possible combinations of numbers using one number from each allele pair.
There are 8 possible combinations which are:
135
145
235
245
136
146
236
246
3. Write the alleles that correspond to each number in the combinations. Using the example
from above, the gametes would be:
RSM RsM rSM rsM
RSm Rsm rSm rsm
I created strips of card stock with 8 one inch squares for the students to copy into their gametes
into (see picture below).
The students then use these strips to complete the scavenger hunt. I made 8x8 Punnett squares
with a 1 inch grid and had them laminated so the students could use dry-erase markers to
complete the crosses. Their strips with gametes lined up perfectly and this saved lots of paper.
The picture below shows how the Punnett squares were set up.
If a student starts with a parental genotype with two dominant alleles for any of the traits, there
are some offspring that they are unable to produce. I didn’t tell them this up front but we did
discuss it at the end of the activity.
I also told the students that they had to use the Punnett squares to find their offspring. However,
if they found 2 offspring listed for the scavenger hunt before they completed the square, they
could stop and didn’t have to fill out the whole thing.