Name: _______________________________
Date: ________________________________
Due: ________________________________
Monster Genetics Lab
Pre Lab Discussion
Heredity is the passing on of traits, or characteristics, from parent to offspring. The units of heredity are
called genes. Different versions of the same gene are called alleles. Genes are found on the chromosomes
in a cell. The combinations of genes for each trait occur by chance.
When one allele in a pair is stronger than the other allele, the trait of the weaker allele is masked, or
hidden. The stronger allele is the dominant allele, and the allele that is masked is the recessive allele.
Dominant alleles are written as capital letters and recessive alleles are written as lowercase letters. If both
alleles are different, the trait is said to be heterozygous, or hybrid. Sometimes alleles are neither dominant
nor recessive. The result of such a situation is a blending of traits.
The genetic makeup of an individual is known as its genotype. The observable physical characteristics of an
individual that are the result of the genotype are known as its phenotype.
In humans, the sex of an individual is determined by the particular combination of the two sex
chromosomes. Individuals that have two X chromosomes (XX) are females, whereas those with an X and a Y
chromosome (XY) are males.
In this investigation, you will work with a partner to observe how the results of different gene combinations
produce certain traits.
Problem: How are traits inherited?
Materials:
Pencil
Lab Sheet
Two Coins
Procedure:
1. Clear an open space on your lab table in which to toss the coins.
2. You and your partner should now toss your coins at the same time.
Heads = allele 1, Tails = allele 2
Example: If you flip two heads, your monster will have two copies of allele 1 for its genotype. The
two coins should be flipped only once for each trait.
3. Determine the genotype for each trait and record it in Table 1.
4. Determine the phenotype resulting from the allele pair for each trait and record it in Table 1.
5. Repeat steps 1-2 for each trait and complete Table 1.
6. Draw a picture of your female monster in the space provided on the last page.
Table 1: Genotypes & Phenotypes for Female Monster
Trait
Allele 1
Allele 2
Genotype
Phenotype
Eye
Two small eyes (E)
One large eye (e)
Tail Shape
Curly (C)
Straight (c)
Tail Color Purple (P) Orange (p)
Teeth
Sharp (S)
Round (s)
Horn Color
Purple (W)
White (w)
Ear Shape
Pointy (Y)
Round (y)
Claws
Long (L)
Short (l)
Skin Color
Green (G)
Blue (B)
