Sex Linked, Limited and Influenced Traits Essay

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When Gender Matters: Sex Linked, Sex Limited and Sex Influenced Traits For most inherited traits, the gender of the bearer of the genes is immaterial. Characteristics like free earlobes, fur color, etc., generally operate the same in males as they do in females. But there are exceptions. These fall into three primary categories. Sex Linked Traits are traits whose loci are literally on the sex chromosomes, so their transmission from generation to generation is affected by the sex chromosome complement of the individual. In any species with non-homologous sex chromosomes, these traits can be significant. The first demonstration of sex linkage was the white eye gene in Drosophila, the fruit fly which has become so important to the study of classical genetics. Normal fruit fly eye color is a dull brick red. Mutations in this gene cause the eyes to be white. The white allele is recessive, but it was quickly determined that the inheritance pattern for this gene was different from those of other genes being studied. In some kinds of matings, reciprocal crosses produced different results, something which had never been observed to happen with other genes. Not only that, but in some kinds of matings, the results for the male offspring would be different from the results for the female offspring. For instance, if a white-eyed female was mated to a red-eyed male, all of the female offspring would be red eyed, but all of the male offspring would be white eyed. It turned out that this particular eye color gene was literally located on the X chromosome. Since females have two X chromosomes and males have only one, genetic effects in the two genders are different. And since females contribute an X to each offspring, male or female, and males contribute X chromosomes only to female offspring, naturally transmission patterns were different in different kinds of

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