Which statement describes X-linked traits? O X-linked traits are carried on the autosomes that have an "x"-shaped configuration. O X-linked traits are carried on the X chromosome. O X-linked traits are carried on the Y chromosome.
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X-linked traits are traits whose genes are located on the X chromosome. The X chromosome is one of the two sex chromosomes in humans (XX for females, XY for males). Show more…
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These traits will show a range of phenotypes within a population, known as ____________________ variation. 36. A sex-linked trait is a trait that is expressed from genes on either the ______ or ______ chromosomes. It is more likely that a sex-linked trait and its gene will be on the ______ chromosome because it is a larger chromosome. 37. A female that has one copy of a mutated gene and one normal copy of the gene will not show the mutated phenotype, but will instead be a ____________________ of the mutated phenotype. 38. Males only have one copy of the X chromosome, so they will only need one copy of a mutated X chromosome gene to have the mutated phenotype. Make a Punnet square showing the genotypes and phenotypes of offspring of a mother that is not colorblind, but is a carrier for colorblindness (X = normal, x = colorblind; her genotype is Xx) and a father that is not colorblind (his genotype is XY) below (you can do this on a separate piece of paper and take a picture - #38). F1 genotypes and percentages: _____________________________________________________________________ F1 phenotype and percentages: _____________________________________________________________________ 39. Autosomes are non-sex chromosomes and genes will therefore be on chromosomes 1-22. Individuals, regardless of gender, will have two copies of each of these genes. When a disorder or disease only occurs in an individual when it has two copies of a mutated allele that is RECESSIVE to the normal, completely dominant gene, we call it an ________________________________________ (3 words). An example of this type of disease is ________________________________________ (3 words). These disorders tend to stay in populations because they can be masked in heterozygous individuals. Make a Punnet square showing the genotypes and phenotypes of offspring of a mother that does not have sickle cell anemia, but is a carrier for sickle cell anemia (S = normal, s = sickle cell) and a father that does not have sickle cell anemia, but is a carrier for sickle cell anemia (you can do this on a separate piece of paper and take a picture - #39).
Adi S.
Traits that are carried on the X chromosome are said to be X-linked, gametalleles, or autosomal alleles.
Rabeya Z.
X-linked Disorders Traits carried on the sex (X or Y) chromosomes have a different inheritance pattern than those on the autosomal chromosomes. Although the X and Y chromosomes line up in meiosis I, they are not homologous and do not carry the same genes. For this reason, there is often only one allele present for a trait rather than two. X-linked disorders are carried on the X chromosome. Females have two copies of the X chromosomes, while males only have a single copy of the X chromosome. The cells of males only contain a single X chromosome; therefore, they cannot be considered homozygous or heterozygous for that allele. Instead, they are considered hemizygous, meaning that they only carry a single allele for that gene. For X-linked recessive disorders, because XY individuals are hemizygous, they are more commonly affected compared to XX individuals. X-linked Dominant For X-linked dominant traits, if the allele is present, it is expressed. Hypophosphatemic rickets is an X-linked dominant disease that causes rickets (weakening of the bone due to abnormal ossification). XR represents the Hypophosphatemic rickets allele. Xr represents the normal allele. Answer the following questions about a cross between a father who is Xr Y and a mother who is XR XR. What is the father's genotype (hemizygous dominant or hemizygous recessive)? What is the mother's genotype (heterozygous, homozygous dominant, or homozygous recessive)? What is the father's phenotype (affected or unaffected)? What is the mother's phenotype (affected, unaffected, carrier)? What are the potential gametes produced by the father? What are the potential gametes produced by the mother? Complete a Punnett square for a cross between these two individuals. Parent #1 -> Parent #2 -> What is the predicted ratio of phenotypes for the cross described? X-linked Recessive X-linked recessive traits are more likely to be expressed in males than in females. This is due to the hemizygous genotype. If only a single allele is present, and that allele is recessive, it will be expressed. In females, there are two alleles, and a dominant allele can mask the recessive allele. Hemophilia A affects approximately 1 in 4,000 males (NIH 2009). Hemophilia is caused by a lack of blood clotting factors. This can result in excessive bleeding that does not slow at a normal pace. XH represents the normal allele. Xh represents the hemophilia A allele. Answer the following questions about a cross between a father who is Xh Y and a mother who is XH Xh. What is the father's genotype (hemizygous dominant or hemizygous recessive)? What is the mother's genotype (heterozygous, homozygous dominant, or homozygous recessive)? What is the mother's phenotype (affected or unaffected)? What are the potential gametes produced by the father? What are the potential gametes produced by the mother? Complete a Punnett square for a cross between these two individuals. Parent #1 -> Parent #2 -> What is the predicted ratio of phenotypes for the cross described?
Katlin K.
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