Which trait is controlled by multiple alleles in humans

Each gene is responsible for a distinct aspect of the fly and is subject to mutation and the emergence of new alleles. Normally, the wings of Drosophila melanogaster are quite long. When a fly with vestigial wings is crossed with another with antlered wings, the resulting F1 hybrids have intermediate wing lengths, indicating that none of the mutated genes is dominant.

Occasionally referred to as the vestigial antlered compound, this hybrid contains two mutated genes at the same locus. Mendelian segregation and recombination are evident.

Apart from the vestigial and antlered wings, there are other phenotypes: nicked wings, strap wings, or no wings at all. The gene variants responsible for these phenotypes are the multiple alleles in this particular fruit fly population. There are traits in humans and other organisms that have three or more different types of alleles genes.

When a trait has three or more distinct alleles, we refer to it as having multiple alleles inheritance. If the allele A is present on the chromosome, protein A is produced, and the red blood cells of that individual contain protein A on their membrane.

Finally, if allele i is present on the chromosome, neither protein A nor protein B will be synthesized. These three alleles make up the ABO blood group trait. The inheritance pattern of allele A and allele B shows codominance co-dominance. Co-dominance occurs when neither allele is dominant over the other, and a heterozygous individual expresses both phenotypes. That is, if an individual possesses allele A on one chromosome and allele B on the second homologous chromosome, both proteins are expressed and red blood cells contain both protein A and protein B on their cell membranes.

The ABO blood type hereditary scheme in human beings is an illustration of multiple alleles blood types. Phenotypes are classified into four categories: blood group A, blood group B, blood group AB, and blood group O. In this case, the population has three alleles. The I A allele when expressed results in the presence of A molecules on red blood cells, the I B allele expression leads to the presence of B molecules on red blood cells, and the I O allele expression results in the absence of such antigens on the red blood cells.

Although a population contains three alleles, each individual inherits only two of them from their parents. This results in the genotypes and phenotypes depicted below. Consider that when three alleles are present, there are six distinct genotypes. The number of phenotypes possible is determined by the dominance relationships between the three alleles. Watch the video below to understand multiple alleles in the form of ABO Blood types. While it is widely believed that potato tuber shape is continuous, visual phenotypes such as round or long tubers can be discerned at the diploid level.

Although experimental evidence for the presence of multiple allele systems for a potato tuber is being reported for the first time, this study in potato can be compared to one in maize.

The recessive allele for tuber shape can be regarded as the qualitatively recognized null or near-null allele. Variation between dominant alleles is quantitative. The view that the most recessive allele can be considered a null or near-null allele is consistent with how quantitative effects at a multiallelic locus are described. When additional metric traits are resolved into Mendelian factors using heterozygous parents in experimental designs, conclusions can be drawn about the relative importance of multiple alleles traits to multiple loci in explaining quantitative genetic alleles variation.

Bacteria possess a large number of genes, several of which have multiple alleles. These various wild-type alleles are frequently associated with distinct types of virulence and can be used to classify subspecies e. As a result, it is critical to rapidly identify not only the desired gene but also the relevant allele. Currently available sequencing-based methods are limited to mapping reads to each known allele reference, which is a lengthy process. Understanding and predicting the pathogenic impact and outbreak potential of a bacterial infection requires more than knowledge of the species responsible for the infection.

Bacterial virulence is frequently regulated on a sub-species level by a collection of specific genes or even alleles, necessitating the use of distinct treatment strategies for infections caused by the same bacterial species. And this is why people are not the exact height of their parents. Skin color is another trait that is very obvious in humans that is controlled by many, many different genes.

And this is why you get differences between parents and children in skin color, although they tend to resemble one another. Polygenic traits are quite different from the classical Mendelian trait in where we see that one gene controls one characteristic or one phenotype.

Surprisingly, most traits in humans, and in fact most traits in most organisms, are polygenic. Mendelian traits, although we spend a lot of time talking about them, are really the exception. Being haploid, P. In Southeast Asia, different sulfadoxine-resistant alleles of the dhps gene are localized to different geographic regions.

This is a common evolutionary phenomenon that occurs because drug-resistant mutants arise in a population and interbreed with other P. Sulfadoxine-resistant parasites cause considerable human hardship in regions where this drug is widely used as an over-the-counter malaria remedy. As is common with pathogens that multiply to large numbers within an infection cycle, P.

For this reason, scientists must constantly work to develop new drugs or drug combinations to combat the worldwide malaria burden. Improve this page Learn More. Skip to main content. Module Trait Inheritance. Search for:. Multiple Alleles Learning Outcomes Explain how mutli-allele inheritance will impact a trait within in a population.

Multiple Alleles Confer Drug Resistance in the Malaria Parasite Malaria is a parasitic disease in humans that is transmitted by infected female mosquitoes, including Anopheles gambiae Figure 3a , and is characterized by cyclic high fevers, chills, flu-like symptoms, and severe anemia.

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