Select The Correct Answer.In Chickens, A Flat Single Comb Is A Recessive Trait, While The Short, Thick Rose Comb Is Dominant. In A Particular Population Of Chickens, 45 Are Homozygous For The Dominant Trait, 30 Are Heterozygous Dominant, And 25 Have
Understanding Genetics: A Case Study of Chicken Combs
In the fascinating world of genetics, understanding the interactions between dominant and recessive traits is crucial for grasping the complexities of heredity. The humble chicken, with its diverse array of comb types, provides an excellent example of this concept. In this article, we will delve into the genetics of chicken combs, exploring the relationship between dominant and recessive traits in a particular population of chickens.
The Genetics of Chicken Combs
In chickens, the type of comb is determined by a single gene with two alleles: one for the flat single comb (recessive) and one for the short, thick rose comb (dominant). This means that an individual chicken can be homozygous recessive (ff), homozygous dominant (FF), or heterozygous (Ff), where F represents the dominant allele and f represents the recessive allele.
Homozygous Dominant (FF) Chickens
In the population of chickens we are studying, 45 are homozygous for the dominant trait (FF). This means that these chickens have two copies of the dominant allele, one from each parent. As a result, they will always express the dominant trait, which is the short, thick rose comb.
Heterozygous Dominant (Ff) Chickens
On the other hand, 30 chickens in the population are heterozygous dominant (Ff). This means that they have one copy of the dominant allele and one copy of the recessive allele. Since the dominant allele is expressed in the presence of the recessive allele, these chickens will also express the dominant trait, which is the short, thick rose comb.
Homozygous Recessive (ff) Chickens
Finally, 25 chickens in the population are homozygous recessive (ff). This means that they have two copies of the recessive allele, one from each parent. As a result, they will always express the recessive trait, which is the flat single comb.
Genotype and Phenotype
To summarize, the genotype of a chicken refers to its genetic makeup, while the phenotype refers to its physical characteristics. In this case, the genotype of a chicken can be FF, Ff, or ff, while the phenotype can be either the short, thick rose comb (dominant) or the flat single comb (recessive).
Punnett Squares
To predict the probability of different genotypes and phenotypes in the offspring of two chickens, we can use a Punnett square. A Punnett square is a diagram that shows the possible combinations of alleles that can be inherited by an offspring.
Punnett Square for FF x FF
Let's consider the cross between two homozygous dominant chickens (FF x FF). The Punnett square for this cross would be:
| F | f | |
|---|---|---|
| F | FF | Ff |
| f | Ff | ff |
As we can see, the possible genotypes of the offspring are FF, Ff, and ff. Since the dominant allele is expressed in the presence of the recessive allele, the phenotype of the offspring will always be the short, thick rose comb.
Punnett Square for FF x Ff
Now, let's consider the cross between a homozygous dominant chicken (FF) and a heterozygous dominant chicken (Ff). The Punnett square for this cross would be:
| F | f | |
|---|---|---|
| F | FF | Ff |
| f | Ff | ff |
As we can see, the possible genotypes of the offspring are FF, Ff, and ff. Since the dominant allele is expressed in the presence of the recessive allele, the phenotype of the offspring will always be the short, thick rose comb.
Punnett Square for Ff x Ff
Finally, let's consider the cross between two heterozygous dominant chickens (Ff x Ff). The Punnett square for this cross would be:
| F | f | |
|---|---|---|
| F | FF | Ff |
| f | Ff | ff |
As we can see, the possible genotypes of the offspring are FF, Ff, and ff. Since the dominant allele is expressed in the presence of the recessive allele, the phenotype of the offspring will always be the short, thick rose comb.
Conclusion
In conclusion, the genetics of chicken combs provides a fascinating example of the interactions between dominant and recessive traits. By understanding the genotype and phenotype of a chicken, we can predict the probability of different genotypes and phenotypes in the offspring of two chickens. The Punnett square is a powerful tool for predicting the outcomes of genetic crosses, and it has many applications in fields such as agriculture, medicine, and biotechnology.
References
- Bateson, W. (1909). Mendel's Principles of Heredity. Cambridge University Press.
- Mendel, G. (1866). Experiments on Plant Hybridization. Journal of the Royal Horticultural Society, 1, 1-32.
- Sturtevant, A. H. (1913). The Linnean Society of London and the Origin of Species. The Linnean Society of London, 1-12.
Further Reading
- Biology: The Core by Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, and Jane B. Reece
- Genetics: From Genes to Genomes by Leland Hartwell, Leroy Hood, Michael L. Goldberg, Ann E. Reynolds, and James E. Silver
- Molecular Biology of the Cell by Bruce Alberts, Alexander Johnson, Julian Lewis, Martin Raff, Keith Roberts, and Peter Walter
Frequently Asked Questions: Understanding Genetics and Chicken Combs
In our previous article, we explored the fascinating world of genetics and chicken combs, delving into the interactions between dominant and recessive traits. We also discussed the use of Punnett squares to predict the probability of different genotypes and phenotypes in the offspring of two chickens. In this article, we will answer some of the most frequently asked questions about genetics and chicken combs.
Q: What is the difference between genotype and phenotype?
A: The genotype of a chicken refers to its genetic makeup, while the phenotype refers to its physical characteristics. In the case of chicken combs, the genotype can be FF, Ff, or ff, while the phenotype can be either the short, thick rose comb (dominant) or the flat single comb (recessive).
Q: What is the dominant allele in the case of chicken combs?
A: The dominant allele in the case of chicken combs is the allele that codes for the short, thick rose comb. This allele is represented by the letter F.
Q: What is the recessive allele in the case of chicken combs?
A: The recessive allele in the case of chicken combs is the allele that codes for the flat single comb. This allele is represented by the letter f.
Q: What is a Punnett square?
A: A Punnett square is a diagram that shows the possible combinations of alleles that can be inherited by an offspring. It is a powerful tool for predicting the outcomes of genetic crosses.
Q: How do I use a Punnett square to predict the probability of different genotypes and phenotypes in the offspring of two chickens?
A: To use a Punnett square, you need to know the genotype of the two parents. You then draw a square with the alleles of the two parents on the top and left sides. The possible combinations of alleles that can be inherited by the offspring are then listed in the squares. The probability of each genotype and phenotype can be calculated by counting the number of squares that contain each combination.
Q: What is the probability of a chicken being homozygous dominant (FF) if one parent is homozygous dominant (FF) and the other parent is heterozygous dominant (Ff)?
A: To calculate the probability of a chicken being homozygous dominant (FF) if one parent is homozygous dominant (FF) and the other parent is heterozygous dominant (Ff), we need to use a Punnett square. The Punnett square for this cross would be:
| F | f | |
|---|---|---|
| F | FF | Ff |
| f | Ff | ff |
As we can see, the possible genotypes of the offspring are FF, Ff, and ff. Since the dominant allele is expressed in the presence of the recessive allele, the phenotype of the offspring will always be the short, thick rose comb. The probability of a chicken being homozygous dominant (FF) is therefore 1/2, since there is a 50% chance that the offspring will inherit the dominant allele from each parent.
Q: What is the probability of a chicken being heterozygous dominant (Ff) if one parent is homozygous dominant (FF) and the other parent is heterozygous dominant (Ff)?
A: To calculate the probability of a chicken being heterozygous dominant (Ff) if one parent is homozygous dominant (FF) and the other parent is heterozygous dominant (Ff), we need to use a Punnett square. The Punnett square for this cross would be:
| F | f | |
|---|---|---|
| F | FF | Ff |
| f | Ff | ff |
As we can see, the possible genotypes of the offspring are FF, Ff, and ff. Since the dominant allele is expressed in the presence of the recessive allele, the phenotype of the offspring will always be the short, thick rose comb. The probability of a chicken being heterozygous dominant (Ff) is therefore 1/2, since there is a 50% chance that the offspring will inherit the dominant allele from one parent and the recessive allele from the other parent.
Q: What is the probability of a chicken being homozygous recessive (ff) if one parent is homozygous dominant (FF) and the other parent is heterozygous dominant (Ff)?
A: To calculate the probability of a chicken being homozygous recessive (ff) if one parent is homozygous dominant (FF) and the other parent is heterozygous dominant (Ff), we need to use a Punnett square. The Punnett square for this cross would be:
| F | f | |
|---|---|---|
| F | FF | Ff |
| f | Ff | ff |
As we can see, the possible genotypes of the offspring are FF, Ff, and ff. Since the dominant allele is expressed in the presence of the recessive allele, the phenotype of the offspring will always be the short, thick rose comb. The probability of a chicken being homozygous recessive (ff) is therefore 1/4, since there is a 25% chance that the offspring will inherit the recessive allele from both parents.
Conclusion
In conclusion, understanding genetics and chicken combs is a fascinating and complex topic. By using Punnett squares and understanding the interactions between dominant and recessive traits, we can predict the probability of different genotypes and phenotypes in the offspring of two chickens. We hope that this article has provided you with a better understanding of genetics and chicken combs, and that you will find it useful in your future studies.
References
- Bateson, W. (1909). Mendel's Principles of Heredity. Cambridge University Press.
- Mendel, G. (1866). Experiments on Plant Hybridization. Journal of the Royal Horticultural Society, 1, 1-32.
- Sturtevant, A. H. (1913). The Linnean Society of London and the Origin of Species. The Linnean Society of London, 1-12.
Further Reading
- Biology: The Core by Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, and Jane B. Reece
- Genetics: From Genes to Genomes by Leland Hartwell, Leroy Hood, Michael L. Goldberg, Ann E. Reynolds, and James E. Silver
- Molecular Biology of the Cell by Bruce Alberts, Alexander Johnson, Julian Lewis, Martin Raff, Keith Roberts, and Peter Walter