Name________________________
Genetics of the Baxter Slug
Learning Targets
Learn and apply vocabulary: gene, allele, dominant, recessive, genotype, phenotype.
I can relate genotypes to phenotypes.
I can show how Meiosis selects alleles for sperm and egg cells.
I can explain how genes and traits are passed from parents to offspring.
Introduction
Baxter Slugs reproduce sexually, just like humans. These traits are controlled by their genes (found on
chromosomes) and have two different alleles each:
Trait
Eye Shape
Body Pattern
Teeth
Gender
Phenotype
Round Eyes
Star Eyes
Polka-Dotted Body
Striped Body
Buck-Teeth
Fangs for Teeth
Male (no eyelashes)
Female (long eyelashes)
Symbol for Allele
R
r
D
d
B
b
Y
X
In this activity, you will analyze the genotypes and phenotypes of two parent slugs. You will then
simulate Meiosis in both parents to produce sperm and egg cells. Finally, you will produce an offspring
slug and analyze its genotypes and phenotypes.
Procedure & Results
Part One – Daddy Slug and his Sperm
1. Obtain a set of chromosomes for Daddy Slug.
2. Record the genotypes and phenotypes of Daddy Slug in your table.
3. Make a sketch of Daddy Slug based on his phenotypes (NOTE: give males no eyelashes).
4. Cut out Daddy Slug’s chromosomes.
5. Simulate Meiosis (you will need to replicate all of the chromosomes, perform Meiosis I, then perform
Meiosis II). The end result should be 4 sperm cells. Check your sperm cells with your teacher.
6. Randomly pick one sperm cell to work with and discard the other ones. Enter the alleles of the chosen
sperm cell into the table (NOTE: the sperm cell should only have ONE copy of each gene!).
Table 1: Daddy Slug Genotypes and Phenotypes
Sketch of Daddy:
Trait
Genotype Phenotype
Eye Shape
Body Pattern
Teeth
Gender
Sperm
Cell Allele
Part Two – Mama Slug and her Eggs
1. Obtain a set of chromosomes for Mama Slug.
2. Record the genotypes and phenotypes of Mama Slug in your table.
3. Make a sketch of Mama Slug based on her phenotypes (NOTE: give females eyelashes).
4. Cut out Mama Slug’s chromosomes.
5. Simulate Meiosis (you will need to replicate all of the chromosomes, perform Meiosis I, then perform
Meiosis II). The end result should be 4 egg cells. Check your egg cells with your teacher.
6. Randomly pick one egg cell to work with and discard the other ones. Enter the alleles of the chosen
egg cell into the table (NOTE: the egg cell should only have ONE copy of each gene!).
Table 2: Mama Slug Genotypes and Phenotypes
Sketch of Mama:
Trait
Genotype Phenotype
Eye Shape
Egg Cell
Allele
Body Pattern
Teeth
Gender
Part Three – Slug Reproduction!
1. Have the sperm cell fertilize the egg cell by combining the chromosomes from the sperm and egg cells
to form an embryo.
2. Pair the homologous chromosomes in the new embryo. Check your embryo with your teacher.
3. For each trait, record the allele from Daddy, the allele from Mama, the genotype and the phenotype in
the Baby Slug table.
4. Make a sketch of Baby Slug based on his/her phenotypes.
Table 3: Baby Slug Genotypes and Phenotypes
Allele
Allele
Trait
from
from
Genotype
Daddy Mama
Eye Shape
Sketch of Baby:
Phenotype
Body Pattern
Teeth
Gender
Analysis Questions
Please answer these questions fully and thoughtfully after completing the activity.
1. How many copies of each chromosomes does Daddy Slug have?_____
2. How many copies of each chromosome are in a sperm cell?_____
3. How it is possible for two Round-Eyed parent slugs to have a Star-Eyed baby. Explain this, and show
the Daddy genotype and Mama genotype that could lead to this.
4. Compare your Baby Slug to those of other groups. Most of the Baby Slugs should look different from
each other even though you all used the same parents for this activity. Explain why this is.