Incomplete and codominance worksheet answer – Embark on an enlightening journey as we delve into the intricacies of incomplete and codominance, unraveling the genetic mechanisms that shape our traits. This comprehensive guide, encompassing both theory and practical application, will provide a profound understanding of these fundamental concepts.
Delving into the realm of incomplete dominance, we explore its definition, uncover captivating examples, and elucidate the underlying genetic principles. We then shift our focus to codominance, unraveling its defining characteristics, showcasing real-world instances, and illuminating the genetic basis of this fascinating phenomenon.
Incomplete Dominance
Incomplete dominance is a genetic phenomenon where the heterozygous genotype of a gene expresses a phenotype that is intermediate between the phenotypes of the homozygous genotypes. In other words, neither allele is dominant over the other.
- Examples of incomplete dominance:
- Snapdragons: When a homozygous red snapdragon (RR) is crossed with a homozygous white snapdragon (rr), the F1 generation will produce pink snapdragons (Rr).
- Four-o’clocks: When a homozygous red four-o’clock (RR) is crossed with a homozygous white four-o’clock (rr), the F1 generation will produce pink four-o’clocks (Rr).
- Carnations: When a homozygous red carnation (RR) is crossed with a homozygous white carnation (rr), the F1 generation will produce pink carnations (Rr).
- Genetic mechanism behind incomplete dominance:In incomplete dominance, the alleles of a gene are codominant, meaning that neither allele is dominant over the other. This results in the heterozygous genotype expressing a phenotype that is a blend of the phenotypes of the homozygous genotypes.
Codominance
Codominance is a genetic phenomenon where both alleles of a gene are fully expressed in the heterozygous genotype. In other words, neither allele is dominant over the other.
- Examples of codominance:
- Blood types: In the human ABO blood group system, there are three alleles: A, B, and O. The A and B alleles are codominant, meaning that individuals with the heterozygous genotype AB will have both A and B antigens on their red blood cells.
- Sickle cell anemia: In sickle cell anemia, there are two alleles: the normal allele (HbA) and the sickle cell allele (HbS). The HbA allele is dominant over the HbS allele, meaning that individuals with the heterozygous genotype HbAS will have both normal and sickle-shaped red blood cells.
- Bombay phenotype: The Bombay phenotype is a rare blood type that results from the inheritance of two recessive alleles (hh) for the H antigen. Individuals with the Bombay phenotype will have neither A nor B antigens on their red blood cells.
- Genetic mechanism behind codominance:In codominance, the alleles of a gene are codominant, meaning that neither allele is dominant over the other. This results in the heterozygous genotype expressing both phenotypes of the homozygous genotypes.
Worksheet Answers
| Genotype | Phenotype | Explanation |
|---|---|---|
| RR | Red | Homozygous dominant genotype |
| Rr | Pink | Heterozygous genotype with incomplete dominance |
| rr | White | Homozygous recessive genotype |
| AA | Type A | Homozygous dominant genotype for blood type A |
| AB | Type AB | Heterozygous genotype with codominance for blood type A and B |
| BB | Type B | Homozygous dominant genotype for blood type B |
| hh | Bombay phenotype | Homozygous recessive genotype for the H antigen |
| HbAHbA | Normal red blood cells | Homozygous dominant genotype for normal hemoglobin |
| HbAHbS | Sickle-shaped and normal red blood cells | Heterozygous genotype with codominance for normal and sickle cell hemoglobin |
| HbSHbS | Sickle-shaped red blood cells | Homozygous recessive genotype for sickle cell hemoglobin |
Detailed FAQs: Incomplete And Codominance Worksheet Answer
What is the key difference between incomplete dominance and codominance?
In incomplete dominance, neither allele is dominant, resulting in an intermediate phenotype. In codominance, both alleles are expressed fully, leading to a distinct phenotype.
Can you provide an example of incomplete dominance?
Snapdragons exhibit incomplete dominance for flower color. When red and white alleles are present, the resulting phenotype is pink flowers.
What is the genetic mechanism behind codominance?
Codominance occurs when both alleles of a gene are fully expressed in the phenotype. This is due to the equal dominance of both alleles.
