Bio Unit 7.1 Discussion

Bio Unit 7.1 Discussion - (1). Please give an example to...

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(1). Please give an example to discuss the X-linked human phenotypes. Chapter 10 of our textbook, Life: The Science of Biology , covered x-linked human phenotypes extensively. I will start this discussion by more broadly describing the inheritance of sex chromosomes in humans. I will then discuss the inheritance of x-linked traits, with special attention given to X-linked disorders. According to our textbook, a single chromosome, Y, determines whether the sex of a human is male or female. Females and males each have an X chromosome. However, females have a second X chromosome (XX) and males have a Y chromosome (XY). As a result, males produce two kinds of gametes that differ on the basis of which sex chromosome they will pass onto their offspring. Half of the male gametes carry the X chromosome and the other half of the gametes carry a Y chromosome. Unlike genes on autosomes, which are chromosomes that are not sex chromosomes, genes on sex chromosomes are inherited in special ways that do not show mendelian inheritance. Furthermore, the Y chromosome does not carry many known genes, whereas many genes are actually found on the X chromosome. With that being said, females, who are XX, carry two copies of the genes on the X chromosome and males, who are XY, only carry one gene. Because of this, the textbook describes how males are “hemizygous” for genes on the X chromosome because they will only have 1 copy of the gene. Whatever gene is present on the X chromosome will therefore be expressed. Before describing X-linked human phenotypes, let’s first discuss the inheritance of a common X-linked phenotype among drosophila flies, eye color. Among drosophila flies, we often see that these insects have red eyes. However, it is possible for some male flies
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Bio Unit 7.1 Discussion - (1). Please give an example to...

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