Student Exploration: Chicken Genetics
Vocabulary: allele, codominance, dominant, genotype, heterozygous, homozygous, phenotype,
probability, Punnett square, recessive, trial
Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
1. The image shows a flower that was produced by crossing
a pure red flower with a pure white flower. Which do you
i
think is the dominant petal color: red or white? Explain.
The dominant petal colour is red because in the photo
there are more red pedals than there are white pedals.
2. How is the inheritance pattern shown by this flower different from other inheritance patterns
you have seen or studied? It’s different because it has both colours on it. Even though the red
is dominant, the recessive allele is also present. On a normal pattern, the dominant would
cover all of the plant.
Gizmo Warm-up
There are many different ways traits can be inherited. Some traits are
governed by alleles that are dominant over other alleles. Other traits are
governed by alleles that share dominance. These alleles follow a pattern of
inheritance called codominance. With the Chicken Genetics Gizmo, you will
study how codominance affects the inheritance of certain traits.
1. Turn on Show genotype. The genotype is the allele combination an
organism has. Point to the red chicken.
A. What is the red chicken’s genotype? F^R F^R
B. What is the white chicken’s genotype? F^W F^W
2. What do you think the letters F, R, and W stand for in the genotypes?
The F probably stands for feather, the R stands for red and W stands for white.
, Get the Gizmo ready:
Activity A:
Drag a red chicken and a white chicken into the
Codominant traits
parent boxes, but don’t click Breed yet.
Question: What inheritance patterns do codominant traits display?
1. Predict: What do you think the offspring of a red chicken and a white chicken will look like?
I believe that there is going to be a mix of white areas and some areas are going to be red.
2. Observe: Click Breed. What are the offspring genotypes? F^R F^W
An organism’s appearance is its phenotype. Describe the offspring’s phenotype.
The chickens had a mix of colours like I predicted. The top of the chicken is white while the
bottom half is red.
3. Experiment: Drag four offspring to the Holding Cages. Click Clear, and then drag one of the
offspring to a parent box. Drag a white chicken to the other box. Click Breed several times.
Describe the resulting genotypes and phenotypes of the offspring.
The result of breeding a white chicken and a mixed chicken is that about half of the offspring have the
genotype F^R F^W and a phenotype of red and white feathers. The rest of the offspring have the
genotype F^W F^W and a phenotype of pure white feathers.
4. Revise and Repeat: Click Clear. Drag another chicken from the Holding Cages to the
parent box. Drag a red chicken to the other box. Click Breed several times.
Describe the resulting genotypes and phenotypes of the offspring.
About half of the offspring have the genotype F^R F^W and a phenotype of red and white feathers.
The rest of the offspring have the genotype F^R F^R and a phenotype of pure red feathers.
5. Explain: In dominant/recessive inheritance patterns, the dominant allele is always expressed
when present. The recessive allele is only expressed when the dominant allele is not
present. Use your observations from this activity to describe how codominant inheritance
patterns differ from dominant/recessive inheritance patterns.
In the case of co-dominant alleles, both alleles are present and dominant. One allele does
not mask the other. This is why the phenotype is half and half. But in a dominant/recessive
pattern, there is a ratio between the offspring being all red or all white.
Vocabulary: allele, codominance, dominant, genotype, heterozygous, homozygous, phenotype,
probability, Punnett square, recessive, trial
Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
1. The image shows a flower that was produced by crossing
a pure red flower with a pure white flower. Which do you
i
think is the dominant petal color: red or white? Explain.
The dominant petal colour is red because in the photo
there are more red pedals than there are white pedals.
2. How is the inheritance pattern shown by this flower different from other inheritance patterns
you have seen or studied? It’s different because it has both colours on it. Even though the red
is dominant, the recessive allele is also present. On a normal pattern, the dominant would
cover all of the plant.
Gizmo Warm-up
There are many different ways traits can be inherited. Some traits are
governed by alleles that are dominant over other alleles. Other traits are
governed by alleles that share dominance. These alleles follow a pattern of
inheritance called codominance. With the Chicken Genetics Gizmo, you will
study how codominance affects the inheritance of certain traits.
1. Turn on Show genotype. The genotype is the allele combination an
organism has. Point to the red chicken.
A. What is the red chicken’s genotype? F^R F^R
B. What is the white chicken’s genotype? F^W F^W
2. What do you think the letters F, R, and W stand for in the genotypes?
The F probably stands for feather, the R stands for red and W stands for white.
, Get the Gizmo ready:
Activity A:
Drag a red chicken and a white chicken into the
Codominant traits
parent boxes, but don’t click Breed yet.
Question: What inheritance patterns do codominant traits display?
1. Predict: What do you think the offspring of a red chicken and a white chicken will look like?
I believe that there is going to be a mix of white areas and some areas are going to be red.
2. Observe: Click Breed. What are the offspring genotypes? F^R F^W
An organism’s appearance is its phenotype. Describe the offspring’s phenotype.
The chickens had a mix of colours like I predicted. The top of the chicken is white while the
bottom half is red.
3. Experiment: Drag four offspring to the Holding Cages. Click Clear, and then drag one of the
offspring to a parent box. Drag a white chicken to the other box. Click Breed several times.
Describe the resulting genotypes and phenotypes of the offspring.
The result of breeding a white chicken and a mixed chicken is that about half of the offspring have the
genotype F^R F^W and a phenotype of red and white feathers. The rest of the offspring have the
genotype F^W F^W and a phenotype of pure white feathers.
4. Revise and Repeat: Click Clear. Drag another chicken from the Holding Cages to the
parent box. Drag a red chicken to the other box. Click Breed several times.
Describe the resulting genotypes and phenotypes of the offspring.
About half of the offspring have the genotype F^R F^W and a phenotype of red and white feathers.
The rest of the offspring have the genotype F^R F^R and a phenotype of pure red feathers.
5. Explain: In dominant/recessive inheritance patterns, the dominant allele is always expressed
when present. The recessive allele is only expressed when the dominant allele is not
present. Use your observations from this activity to describe how codominant inheritance
patterns differ from dominant/recessive inheritance patterns.
In the case of co-dominant alleles, both alleles are present and dominant. One allele does
not mask the other. This is why the phenotype is half and half. But in a dominant/recessive
pattern, there is a ratio between the offspring being all red or all white.
