What happens in incomplete dominance when you cross a red and a white flower?
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The phenotype of a plant is the collective expression of the genotype in conjunction with the impacts of the environment on a plant’s observable characteristics. However, plants of the same genotype interacting with different environments may manifest as different phenotypes; on the other hand, plants may have the same phenotype but different genotypes. The latter may occur in situations where: Show
A gene or genes display incomplete dominance, for example, if a plant is heterozygous for a gene and as a result, its phenotype is intermediate to the two homozygous classes (see Appendix D for dominance, heterozygosity). ▪A gene or genes associated with a phenotype are changed by the presence of modifiers, suppressors, or other regulators produced by other genes (epistasis, epistatic interaction) such that the phenotype is altered (see Chapter 10, Section 3.1.3). ▪A certain combination of environmental conditions affects the relative expression of a gene or genes, or a combination of these factors affects the relative expressivity of a gene or genes, thus altering the degree to which the genotype manifests a phenotype. Phenotypic variation is usually assessed in replicated field trials under a range of environmental conditions that are representative of where the crop is grown. View chapterPurchase book Read full chapter URL: https://www.sciencedirect.com/science/article/pii/B9780128185643000020 Basic Genetics: The Cell, Mitosis and Meiosis, and Mendelian LawsGuan Wang, in Handbook of Pharmacogenomics and Stratified Medicine, 2014 2.4.3 Mendelian Patterns of Inheritance in HumansIn modern genetics, Mendelian principles have been extended to more complex inherited traits than Mendel described. His peas have a relatively simple genetic basis—each character is determined by only one gene with two versions (or alleles), of which one is completely dominant. In fact, the relationship between genotype and phenotype for the majority of heritable traits is very complicated, but the laws of segregation and independent assortment can still be applied. Recall from previous sections that pea characters, such as flower color, seed color, and seed shape, are completely controlled by their respective dominant alleles: P, Y, and R. In the case of flower color, Mendel’s heterozygous F1 offspring (Pp) all had purple flowers because the P allele shows a completely dominant effect over the recessive p allele. However, some heterozygous genotypes may cause incomplete dominance, meaning that the appearance of those heterozygous individuals has an intermediate phenotype between the phenotypes of the parent generation. Along with complete and incomplete dominance patterns of inheritance, there is co-dominance, in which a heterozygous individual expresses both phenotypes of the two alleles. Furthermore, the dominant effect of one allele on a phenotype is reflected by the mechanisms/pathways from genotype to phenotype, which does not imply the ability of one allele to mute another at the DNA level or the abundance of that allele in a population. The relationship between genotype and phenotype may also be explained by multiple gene alleles (instead of only the two reported by Mendel); pleiotropy (i.e., one gene affects several phenotypic traits); epistasis (i.e., a gene at one locus interferes with the expression of a second gene at a different locus); and environment (e.g., nutrition affects human height and sun exposure affects skin color). Some characters, such as human height and skin color, result from an additive effect of two or more genes in a continuous fashion. These characters are said to be polygenic. Environment influences these polygenic traits, which are thus known as multifactorial. Mendel’s discovery of the patterns of individual gene transmission from parents to offspring led to Mendelian models, which were developed and broadly used to explain the inheritance patterns of epistasis and polygenic characters. In the case of human inheritance, family pedigree analysis shows evidence that supports Mendelian patterns, with some following those patterns recessively (i.e., inherited from the heterozygous genotype) or dominantly (i.e., inherited from the dominant allele). Besides these simple Mendelian disorders, humans are more prone to diseases that have a multifactorial basis. For example, heart disease, diabetes, cancer, and many others diseases are the result of multiple genes, interactions between genes, and interactions between genes and the environment. Using technologies developed in recent years, studies have been conducted on the genetic and environmental components of multifactorial human traits. These will be discussed in later chapters. What happens when you cross a red flower and a white flower?The crossing of a red flowered plant and a white flowered plant produces all the offspring with pink flowers. This cross illustrates red and white exhibit incomplete dominance. This situation occurs due to the blending of both the alleles.
Which genotype would represent incomplete dominance when a red and a white flower are crossed?Explanation: The genotypes of the offspring can be determined by crossing the red flowers, RR, with the white flowers, rr. Offspring: all offspring are Rr. Incomplete dominance means that neither color shows dominance in the hybrid generation.
When incomplete dominance is expressed in red and white snapdragons What color is most common?Figure 21: A cross between a red and white snapdragon will yield 100% pink offspring. This pattern of inheritance is described as incomplete dominance, meaning that neither of the alleles is completely dominant over the other: both alleles can be seen at the same time.
What happens during incomplete dominance?Incomplete dominance is when a dominant allele, or form of a gene, does not completely mask the effects of a recessive allele, and the organism's resulting physical appearance shows a blending of both alleles. It is also called semi-dominance or partial dominance. One example is shown in roses.
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