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Explain each of the following phenomena and how they extend our understanding of genetics from the work done by Gregor Mendel and classical inheritance patterns. Provide a real-world example for each:Incomplete Dominance

Co-Dominance
Multiple Alleles
Polygenic Inheritance
Pleiotropy
Epistasis
Sex Linkage
Gene linkage

User Technupe
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●Incomplete dominance is a kind of transitional inheritance of which a allele for a certain trait is partially expressed above its paired allele. This leads to the production of a third phenotype with the expressed physical trait acting as a summation of the phenotypes of both alleles. In incomplete dominance the full dominant trait is not fully expressed. E.g. A red and white flower reproduce to give a pink flower

●Codominance is seen when two “alleles,” of the same type of gene is found and both expressed in an organism. Both traits appear without one trait being dominant over the other trait that is present. It is mostly seen in plants and animals that possess more than a singular pigment color e.g. Blood type, A and B are both dominant (Blood has ia ib shows BOTH A and B carbohydrates).

●multiple alleles: In this case Three or more different forms of a gene (alleles) are located in the same locus with only two of the alleles evident in the singular organism. For example, the ABO system of blood groups is regulated by three alleles, with two of it being found in an individual.

●Polygenic inheritance is seen when one characteristic is regulated by two or more genes that are more in quantity but small in it's impact. E.g. spectrum of colors of different genes that code for a certain trait -skin color

●Pleiotropy is due to the influence of a singular gene known as pleiotropic gene on two or more apparently unrelated phenotypic traits. Such a gene that exhibits multiple phenotypic expression is called a pleiotropic gene e.g. one gene multiple traits of sickle-cell disease.

●Epistasis has to do with interaction of genes which are not alleles, take for instance, the suppression of the activities of a certain gene by another. Example of a one trait but multiple genes is seen in the coat color of Labrador retrievers; yellow, chocolate, black.

●Sex linkage explains the sex-specific process of inheritance and presentation as seen in a gene mutation being found on a sex chromosome instead of a non-sex chromosome. E.g. genes on sex chromosomes Xs and Ys.

●Genetic linkage is the likelihood of DNA sequences which are in proximity in a chromosome to be transferred or passed on together at the meiosis stage of sexual reproduction. E.g. genes for hair color and eye color are linked, this produce specific hair and eye colors that can be inherited together, as seen in blonde hair with blue eyes and brown hair with brown eyes.

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