Question 24 Who is at higher risk of inheriting a sex-linked single gene disorder? Females Both males and females have equal risk Males Those living in conditions of extreme stress
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Step 1: Sex-linked disorders are caused by genes located on the X chromosome. Show more…
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Given how sex-linked conditions involve genes that are carried on the X chromosome, which statement is true regarding sex-linked recessive condition inheritance pattern of males? Group of answer choices possession of a single X chromosome lessens the likelihood that a male will express a defective copy of the genes that cause this set of genetic disorders possession of a single X chromosome increases the likelihood that a male will express a defective copy of the genes that cause this set of genetic disorders genes found on the Y chromosome can protect males from defective genes found on the X chromosome and decreases male likelihood of expressing this set of genetic disorders males and females always have an equal likelihood of showing this set of genetic disorders
Madhur L.
Information: Sometimes a particular trait is found on a sex chromosome, usually X. These genes are called sex-linked genes only because they are located on the sex chromosome X. The characteristic has nothing to do with the sex of the individual. Since females have two X (XX) and males only have one (XY), males have a higher chance of expressing a defective recessive gene since they don't have another X to act as the dominant X. Females with only one defective allele are said to be carriers. Their phenotype is normal, and they do not express the disorder. A Punnett square to determine sex-linked inheritance must include the sex chromosomes X and Y using a lowercase superscript to denote the defective recessive gene located on the X chromosome. A few sex-linked disorders are commonly found worldwide. The first is colorblindness (noted as xc) in which an afflicted individual inherits a defective gene coding for the color-detecting cones of the eye's retina. This individual may have a hard time distinguishing two colors. A second type of sex-linked disorder is the blood clotting defect called hemophilia. An individual with hemophilia cannot produce adequate blood clots and may bleed to death as a result. This disease is noted as Xh where the h is the defective blood-clotting protein. A third type of sex-linked disease is Fragile X syndrome. A person with Fragile X inherits an addition of 600+ nucleotides on the X chromosome which results in abnormal facial features and intellectual disabilities. This is denoted as X1. The fourth and final common sex-linked disorder is Duchenne's muscular dystrophy (Xd) in which the individual inherits a defective muscle protein causing progressively weakened muscles. The average lifespan for someone with Duchenne MD is 25 years. Questions: 1a. What is a sex-linked trait? 1b. Why are males more prone to inherit the disease or disorder? 1c. Why are females considered carriers? Why can't males be carriers? 2a. Cross a male afflicted with colorblindness and a normal woman. 2b. If a female carrier of Fragile X syndrome has children with a normal male, what are the chances that a boy will be born with Fragile X syndrome? 2c. Cross a male with hemophilia with a female carrier of hemophilia. What are the chances they will have a girl with hemophilia? 2d. Cross a female carrier of Duchenne's muscular dystrophy with a healthy male. What are the chances they will have a girl with Duchenne?
Kaela P.
Clearly explain how the number of alleles for sex-linked genes varies in males and females. Include how this affects the genotypes of each sex. In other words, are these terms applicable: homozygous, heterozygous, carriers, etc.? Considering a recessive genetic disorder that is carried on the X-chromosome, should a male child be more concerned if his mother has the disorder or his father has the disorder? Explain your reasoning. How might this differ for a female child? Include at least one properly cited reference.
Adi S.
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