BackIn Drosophila subobscura, the presence of a recessive gene called grandchildless (gs) causes the offspring of homozygous females, but not those of homozygous males, to be sterile. Can you offer an explanation as to why females and not males are affected by the mutant gene?
On the Drosophila X chromosome, the dominant allele y⁺ produces gray body color and the recessive allele y produces yellow body. This gene is linked to one controlling full eye shape by a dominant allele lz⁺ and lozenge eye shape with a recessive allele lz. These genes recombine with a frequency of approximately 28%. The Lz gene is linked to gene F controlling bristle form, where the dominant phenotype is long bristles and the recessive one is forked bristles. The Lz and F genes recombine with a frequency of approximately 32%.
Can any cross reveal genetic linkage between gene Y and gene F? Why or why not?
On the Drosophila X chromosome, the dominant allele y⁺ produces gray body color and the recessive allele y produces yellow body. This gene is linked to one controlling full eye shape by a dominant allele lz⁺ and lozenge eye shape with a recessive allele lz. These genes recombine with a frequency of approximately 28%. The Lz gene is linked to gene F controlling bristle form, where the dominant phenotype is long bristles and the recessive one is forked bristles. The Lz and F genes recombine with a frequency of approximately 32%.
Using any genotypes you choose, design two separate crosses, one to test recombination between genes Y and Lz and the second between genes Lz and F. Assume 1000 progeny are produced by each cross, and give the number of progeny in each outcome category. (In setting up your crosses, remember that Drosophila males do not undergo recombination.)
A woman's father has ornithine transcarbamylase deficiency (OTD), an X-linked recessive disorder producing mental deterioration if not properly treated. The woman's mother is homozygous for the wild-type allele.
For the instance you identified in part (d), what proportion of daughters produced by the woman and the man are expected to have OTD? What proportion of sons of the woman and the man are expected to have OTD?
A woman's father has ornithine transcarbamylase deficiency (OTD), an X-linked recessive disorder producing mental deterioration if not properly treated. The woman's mother is homozygous for the wild-type allele.
Identify a male with whom the woman could produce a daughter with OTD.
A woman's father has ornithine transcarbamylase deficiency (OTD), an X-linked recessive disorder producing mental deterioration if not properly treated. The woman's mother is homozygous for the wild-type allele.
If the woman has a daughter with a man who does not have OTD, what is the chance the daughter will be a heterozygous carrier of OTD? What is the chance the daughter will have OTD?
A woman's father has ornithine transcarbamylase deficiency (OTD), an X-linked recessive disorder producing mental deterioration if not properly treated. The woman's mother is homozygous for the wild-type allele.
If the woman has a son with a man who does not have OTD, what is the chance the son will have OTD?
A woman's father has ornithine transcarbamylase deficiency (OTD), an X-linked recessive disorder producing mental deterioration if not properly treated. The woman's mother is homozygous for the wild-type allele.
What is the woman's genotype? (Use D to represent the dominant allele and d to represent the recessive allele.)
In humans, hemophilia A (OMIM 306700) is an X-linked recessive disorder that affects the gene for factor VIII protein, which is essential for blood clotting. The dominant and recessive alleles for the factor VIII gene are represented by H and h. Albinism is an autosomal recessive condition that results from mutation of the gene producing tyrosinase, an enzyme in the melanin synthesis pathway. A and a represent the tyrosinase alleles. A healthy woman named Clara (II-2), whose father (I-1) has hemophilia and whose brother (II-1) has albinism, is married to a healthy man named Charles (II-3), whose parents are healthy. Charles's brother (II-5) has hemophilia, and his sister (II-4) has albinism. The pedigree is shown below.
If Clara and Charles's first child has albinism, what is the chance the second child has albinism? Explain why this probability is higher than the probability you calculated in part (b).
In humans, hemophilia A (OMIM 306700) is an X-linked recessive disorder that affects the gene for factor VIII protein, which is essential for blood clotting. The dominant and recessive alleles for the factor VIII gene are represented by H and h. Albinism is an autosomal recessive condition that results from mutation of the gene producing tyrosinase, an enzyme in the melanin synthesis pathway. A and a represent the tyrosinase alleles. A healthy woman named Clara (II-2), whose father (I-1) has hemophilia and whose brother (II-1) has albinism, is married to a healthy man named Charles (II-3), whose parents are healthy. Charles's brother (II-5) has hemophilia, and his sister (II-4) has albinism. The pedigree is shown below.
Determine the probability that the first child of Clara and Charles will be a
i. boy with hemophilia
ii. girl with albinism
iii. healthy girl
iv. boy with both albinism and hemophilia
v. boy with albinism
vi. girl with hemophilia <>
In humans, hemophilia A (OMIM 306700) is an X-linked recessive disorder that affects the gene for factor VIII protein, which is essential for blood clotting. The dominant and recessive alleles for the factor VIII gene are represented by H and h. Albinism is an autosomal recessive condition that results from mutation of the gene producing tyrosinase, an enzyme in the melanin synthesis pathway. A and a represent the tyrosinase alleles. A healthy woman named Clara (II-2), whose father (I-1) has hemophilia and whose brother (II-1) has albinism, is married to a healthy man named Charles (II-3), whose parents are healthy. Charles's brother (II-5) has hemophilia, and his sister (II-4) has albinism. The pedigree is shown below.
What are the genotypes of the four parents (I-1 to I-4) in this pedigree? <>
In an earlier Problems and Discussion section (see Chapter 7, Problem 27), we described CC, the cat created by nuclear transfer cloning, whereby a diploid nucleus from one cell is injected into an enucleated egg cell to create an embryo. Cattle, sheep, rats, dogs, and several other species have been cloned using nuclei from somatic cells. Embryos and adults produced by this approach often show a number of different mitochondrial defects. Explain possible reasons for the prevalence of mitochondrial defects in embryos created by nuclear transfer cloning.
A wild-type male and a wild-type female Drosophila with red eyes and full wings are crossed. Their progeny are shown below.
Males Females _
3/8 full wing, red eye 3/4 full wing, red eye
3/8 miniature wing, red eye. 1/4 purple eye, full wing
1/8 purple eye, full wing
1/8 miniature wing, purple eye
What is/are the genotype(s) of females with purple eye? Of males with purple eye and miniature wing?
A wild-type male and a wild-type female Drosophila with red eyes and full wings are crossed. Their progeny are shown below.
Males Females _
3/8 full wing, red eye 3/4 full wing, red eye
3/8 miniature wing, red eye. 1/4 purple eye, full wing
1/8 purple eye, full wing
1/8 miniature wing, purple eye
Using clearly defined allele symbols of your choice, give the genotype of each parent.