The introduction to this chapter described the search for genes that determine pattern baldness in humans. In 1916, Dorothy Osborn suggested that pattern baldness is a sex-influenced trait  that is dominant in males and recessive in females. More research suggested that pattern baldness is an X-linked recessive trait. Would you expect to see independent assortment between genetic markers on the X chromosome and pattern baldness if (a) pattern baldness is sexinfluenced and (b) if pattern baldness is X-linked recessive? Explain your answer.

Q: Let’s suppose that two different X-linked genes exist in mice,designated with the letters N and L.…

A: The distance between the two genes N and L  can be surveyed by making crosses and by examining the…

Q: In humans, as well as in many other animals and some plants, the sex of the individual is determined…

A: Haemophilia is an inherited bleeding disorder where blood doesn't clot properly. It is caused when…

Q: Red-green colorblindness is determined in humans by a single X-linked locus. Colorblind males are…

A: XBY male has normal vision.XbY male has Red-green color blindness.XBXB females are normal…

Q: A human disease known as vitamin D–resistant rickets isinherited as an X-linked dominant trait. If a…

A: Sex determination is the process by which an individual develops into a female or a male. The…

Q: Why is the gene for eye color in drosophila present on the X chromosome ?

A: Gene is the basic unit of heredity for all life forms. It is transferable from one generation to its…

Q: Eye color in Drosophila is determined by a gene is on the X chromosome, with the red-eye allele…

A: Each gene possesses two forms of alleles. These forms include a dominant allele and a recessive…

Q: Miniature wings (Xm) in Drosophila result from an X-linked allele that is recessive to the allele…

A: Alleles are the alternative forms of a gene. Allele can be dominant or recessive.

Q: In humans color vision is X-linked, the gene for color vision is located on the X chromosome but is…

A: Colour blindness is a X linked Recessive disorder in which presence  of gene n on X chromosome is…

Q: Why is the development of individuals with Klinefelter's and Turner's syndromes relatively normal,…

A: This syndrome occur due to presence of an additional copy of X chromosomes resulting into karyotype…

Q: Figure 5.1 presented abbreviated pedigrees looking at the inheritance of X-linked human conditions.…

A: Double heterozygote = Individual 1 in generation II, if the mother in generation I is homozygous…

Q: Butterflies have an X-Y sex-determination system that is different from that of flies or humans.…

A: -The butterfly shown has a completely unique pattern of colors because o a special trait- it has two…

Q: White eye color is a recessive sex-linked trait in fruit flies. If a whiteeyed Drosophila female is…

A: Genes are the hereditary unit of an organism. The DNA (deoxyribonucleic acid) forms the genes. DNA…

Q: Explain why genetic disorders caused by recessive alleles of X-linked genes appear more frequently…

A: In humans and other mammals, biological sex is determined by a pair of sex chromosomes: XY in males…

Q: A purebred, red-eyed female fruit fly is mated with a white-eyed, male fruit fly. White eyes are…

A: All mammalian organisms exhibit sexual dimorphism. It means that there is the presence of a male and…

Q: In humans, hemophilia is an X-linked recessive gene and will only be expressed in females if  they…

A: Hemophilia is a X linked recessive disorder so which is inherited in homozygous condition. In rare…

Q: The Amami spiny rat (Tokudaia osimensis) lacks a Y chromosome, yet scientists at Hokkaido University…

A: Reproduction: Important biological process by which new offspring are reproduced by their parents is…

Q: males, are encoded by different alleles of the same X-linked fur color gene. Based on the phenotypes…

A: As we know that in XY -chromosomal system of sex determination , both X and Y chromosomes are sex…

Q: In humans, color vision depends on genes encoding three pigments. The R (red pigment) and G (green…

A: The inheritance of color vision in humans depends upon three main genes that code for three…

Q: eye color is determined by a recessive allele, v, of an X-linked gene. The wildtype color is…

A: Eye color in Drosophila is an example of a X-linked trait: In Drosophila, the gene for eye color is…

Q: White eyes is a Drosophila phenotype that is linked to a mutant, recessive, X- inked allele.…

A: Sex-linked(X-linked) inheritance is a type of criss-cross inheritance, where the traits from the…

Q: How many Barr bodies in a person with genotype XXXXX? How is the structure of a Barr body different…

A: The mammalian males contain XY chromosome and females contain XX chromosome. So, the number of…

Q: Which of the following disorders in humans has an X-linked recessive inheritance pattern?…

A: X-linked recessive inheritance refers to genetic conditions associated with mutations in genes on…

Q: Color blindness is an X-linked recessive trait. An XX female can be colorblind in one eye due to…

A: X chromosome inactivatiom is a random process. Either of the X chromosome is inactivated in human in…

Q: Another recessive mutation in Drosophila, ebony (e), is on anautosome (chromosome 3) and causes…

A: The scalloped wing phenotype is produced due to a recessive mutation in the X chromosome. The…

Q: Colorblindness and hemophilia are both X-linked traits in humans. Explain how a female who has a…

A: Colourblindness and haemophilia are both X-linked traits in humans. Haemophilia is a bleeding…

Q: Which of the following findings supports the fact that the presence of the Y-chromosome rather than…

A: In mammals the sex chromosomes are X and Y. The genotype for a normal female is XX and that of…

Q: Anhidrotic ectodermal dysplasia is an X-linked recessive disorder in humans characterized by small…

A: The inactivation of the X allele is known to be the major cause of the Anhidrotic ectodermal…

Q: Why is it that so many of the sex-linked traits we talk about in humans are carried on X chromosomes…

A: Traits can be dominant, recessive, sex linked recessive or sex linked dominant. Dominance is the…

Q: The inheritance in short wings in Drosophila fruit flies is an x-linked trait, recessive. Which…

A: X-linked recessive inheritance is caused when a mutation occurs in the X-chromosome therefore a male…

Q: Which sex chromosome (X or Y) carries the gene for eye color in Drosophila? Why?

A: Red eye colour is dominant over white eye colour in drosophila.

Q: Suppose genetic analysis reveals a serious mutation in a gene in the green region of the left-hand…

A: Chromosomes are filamentous bodies present in the nucleus. They have the ability of self-replication…

Q: Human females have two X chromosomes (XX); males have one X and one Y chromosome (XY). a. With…

A: Male has two types of chromosomes are X and Y whereas females have two chromosomes both are X and…

Q: Which of the following statements is false?

A: Aneuploidy is the addition or deletion of one or more chromosomes.  Trisomy is the addition of one…

Q: A homozygous gray female is crossed with a yellow male. The F1 are intercrossed to produce the F2.…

A: It is given that a homozygous gray female is crossed with the yellow male. The yellow color due to…

Q: Anhidrotic ectodermal dysplasia is an X-linked recessive disorder in humans characterized by small…

A: The medical condition Anhidrotic ectodermal dysplasia is caused due to mutation precisely in the…

Q: Researchers discovered recently that the sole functionof the SRY protein is to activate an autosomal…

A: Sex-determining region of Y (SRY) is responsible for maleness in males. Mutation in the SRY region…

Q: Which findings support the fact that the presence of the Y- chromosome rather than the lack of a…

A: In many animals including humans, sex is determined by sex chromosomes, which are X and Y…

Q: In mice, dwarfism is caused by an X-linked recessive allele, and pink coat is caused by an autosomal…

A: According to the given question, In mice, dwarfism is caused by an X-linked recessive allele, and…

Q: Lesch-Nyhan syndrome is caused by a X-linked recessive mutations. Accordingly, Lesch-Nyhan syndrome…

A: Lesch- Nyhan syndrome is caused by the X linked genes. The symptoms includes banging head,…

Q: Cat breeders are aware that kittens expressing the X-linked calico coat pattern and tortoiseshell…

A: Gene is the unit of heredity that is transferable from the parent to the offsprings. The function of…

Q: A certain type of congenital deafness in humans is caused by a rare autosomal (not X-linked)…

A: DNA is the genetic material in most living organisms. It is the information hub of the cell that…

Q: Some individuals grow ear hair later in life, the gene for this trait is beleived to be carried on…

A: The phenotypic expression is the ultimate product of a gene. All of our phenotypic characteristics…

Q: In humans, as well as in many other animals and some plants, the sex of the individual is determined…

A: Haemophilia is X-linked recessive disorder. It is generally caused by a mutation in the genes which…

Q: XX individuals can be sex-reversed males if one of their X chromosomes contains a translocated…

A: In a normal female, there are two X chromosomes and their karyotype is (46, XX). However, in some…

Q: In Drosophila, the genes for withered wings (whd), smooth abdomen (sm) and speck body (sp) are…

A: To calculate the expected number of double crossover, we have to use the product rule. The product…

Q: In humans, the AR gene is located on the X chromosome. If a person who is XY has a complete deletion…

A: Androgen is a steroid hormone secreted in males that bind with the androgen receptors located on…

Q: In 1916, Dorothy Osborn suggested that pattern baldness is a sex-influenced trait that is dominant…

A: Pattern baldness is a sex-influenced trait that is dominant in males and recessive in females. The…

Q: Can the Lyon hypothesis be tested in a human female who is homozygousfor one allele of the X-linked…

A: Lyon hypothesis: The concept that a gene dosage imbalance between males and females is compensated…

Q: Why does the sex chromosome X carry the gene for eye color in Drosophila?

A: The mode of inheritance is a pattern of obtaining parentral alleles  or genes to the offsprings. The…

Mitochondrial Mutations

A mitochondrion is a cellular organelle that serves as the site for cellular respiration and energy production (ATP or Adenosine Triphosphate). It is a double-membrane-bound organelle and is only present in eukaryotic cells.