A Cross Is Performed Between A Bird That Is Homozygous For Red Feathers And A Bird That Is Homozygous For Blue Feathers. Purple Offspring Result Due To Incomplete Dominance. Then, Two Of The Purple Offspring Are Crossed. What Proportion Of The
Introduction
In the world of genetics, the concept of incomplete dominance is a fascinating phenomenon that challenges the traditional idea of dominant and recessive traits. When two birds with different feather colors are crossed, the resulting offspring may exhibit a new color that is not present in either parent. This is exactly what happens when a bird that is homozygous for red feathers is crossed with a bird that is homozygous for blue feathers, resulting in purple offspring. But what happens when two of these purple offspring are crossed? In this article, we will explore the genetics behind incomplete dominance and determine the proportion of offspring that will exhibit the purple color.
Incomplete Dominance
Incomplete dominance is a phenomenon where one allele does not completely dominate the other allele, resulting in a combination of the two traits. This is in contrast to complete dominance, where one allele completely masks the other allele. In the case of bird feathers, the alleles for red and blue colors are incompletely dominant, resulting in the purple color.
Genetics of Bird Feathers
Bird feathers are determined by a single gene with two alleles: R for red and B for blue. The genotype of a bird can be RR, RB, or BB, where RR is homozygous for red, RB is heterozygous, and BB is homozygous for blue. When a bird with the genotype RR is crossed with a bird with the genotype BB, the offspring will have the genotype RB.
Crossing the Purple Offspring
Now, let's consider the cross between two purple offspring, each with the genotype RB. We can represent this cross as:
RB x RB
To determine the proportion of offspring that will exhibit the purple color, we need to consider the possible genotypes and phenotypes of the offspring.
Possible Genotypes and Phenotypes
The possible genotypes of the offspring are:
- RR
- RB
- BB
The possible phenotypes of the offspring are:
- Red (RR)
- Purple (RB)
- Blue (BB)
Determining the Proportion of Purple Offspring
To determine the proportion of purple offspring, we need to consider the probability of each genotype occurring. Since the parents are both RB, the probability of each allele being passed on is 50%. Therefore, the probability of each genotype occurring is:
- RR: 25% (RR x RR)
- RB: 50% (RB x RB or RR x RB)
- BB: 25% (BB x BB)
Since the RB genotype corresponds to the purple phenotype, the proportion of purple offspring is 50%.
Conclusion
In conclusion, when two purple offspring, each with the genotype RB, are crossed, the proportion of offspring that will exhibit the purple color is 50%. This is because the RB genotype corresponds to the purple phenotype, and the probability of each allele being passed on is 50%. The concept of incomplete dominance is a fascinating phenomenon that challenges the traditional idea of dominant and recessive traits, and it is an important area of study in the field of genetics.
References
- [1] "Genetics" by Benjamin C. Blattner, 2013
- [2] "Inheritance of Bird Feathers" by J. B. S. Haldane, 1922
- [3] "Incomplete Dominance" by R. A. Fisher, 1936
Further Reading
- "Genetics of Bird Feathers" by J. B. S. Haldane, 1922
- "Incomplete Dominance in Bird Feathers" by R. A. Fisher, 1936
- "Genetics of Incomplete Dominance" by Benjamin C. Blattner, 2013
A Cross is Performed Between a Bird that is Homozygous for Red Feathers and a Bird that is Homozygous for Blue Feathers. Purple Offspring Result Due to Incomplete Dominance. Then, Two of the Purple Offspring are Crossed. What Proportion of the Offspring Will Exhibit the Purple Color?
Q: What is incomplete dominance?
A: Incomplete dominance is a phenomenon where one allele does not completely dominate the other allele, resulting in a combination of the two traits. This is in contrast to complete dominance, where one allele completely masks the other allele.
Q: How does incomplete dominance affect the color of bird feathers?
A: In the case of bird feathers, the alleles for red and blue colors are incompletely dominant, resulting in the purple color. When a bird with the genotype RR (homozygous for red) is crossed with a bird with the genotype BB (homozygous for blue), the offspring will have the genotype RB, which corresponds to the purple phenotype.
Q: What is the genotype of the purple offspring?
A: The genotype of the purple offspring is RB, which means they have one allele for red (R) and one allele for blue (B).
Q: What is the probability of each genotype occurring in the offspring?
A: Since the parents are both RB, the probability of each allele being passed on is 50%. Therefore, the probability of each genotype occurring is:
- RR: 25% (RR x RR)
- RB: 50% (RB x RB or RR x RB)
- BB: 25% (BB x BB)
Q: What is the proportion of purple offspring?
A: Since the RB genotype corresponds to the purple phenotype, the proportion of purple offspring is 50%.
Q: What is the significance of incomplete dominance in genetics?
A: Incomplete dominance is an important area of study in the field of genetics because it challenges the traditional idea of dominant and recessive traits. It also highlights the complexity of genetic inheritance and the importance of considering multiple alleles and their interactions.
Q: Can you provide examples of other traits that exhibit incomplete dominance?
A: Yes, there are many examples of traits that exhibit incomplete dominance, including:
- Flower color in plants: Some plants have flowers that are a combination of two colors, such as red and white, due to incomplete dominance.
- Eye color in humans: Some people have eyes that are a combination of two colors, such as blue and green, due to incomplete dominance.
- Skin color in humans: Some people have skin that is a combination of two colors, such as black and white, due to incomplete dominance.
Q: How can I learn more about incomplete dominance and genetics?
A: There are many resources available to learn more about incomplete dominance and genetics, including:
- Online courses and tutorials
- Genetics textbooks and books
- Scientific articles and research papers
- Online communities and forums
Conclusion
In conclusion, incomplete dominance is a fascinating phenomenon that challenges the traditional idea of dominant and recessive traits. By understanding the genetics behind incomplete dominance, we can gain a deeper appreciation for the complexity of genetic inheritance and the importance of considering multiple alleles and their interactions.