Often geneticists want to change one allele in an outcrossing organism while keeping the rest of the genome the same. For example, they might wish to take a specially designed stock of flies and alter the eye color from red to white. Suppose that the white-eye allele is dominant, meaning that flies with one or two white-eye alleles will have white eyes. One procedure used is to take a white-eyed fly and cross it with the red-eyed stock. The whiteeyed offspring are then considered to be the first generation, and are crossed with the red-eyed stock. Their white-eyed offspring are considered to be the second generation, and are again crossed with the red-eyed stock, and so forth. The special red-eyed stock is homozygous for the desirable allele A at some other locus, but the white-eyed fly is homozygous for the inferior a allele at that locus. What is the genotype at the eye color locus in the second and subsequent generations?

Often geneticists want to change one allele in an outcrossing organism while keeping the rest of the genome the same. For example, they might wish to take a specially designed stock of flies and alter the eye color from red to white. Suppose that the white-eye allele is dominant, meaning that flies with one or two white-eye alleles will have white eyes. One procedure used is to take a white-eyed fly and cross it with the red-eyed stock. The whiteeyed offspring are then considered to be the first generation, and are crossed with the red-eyed stock. Their white-eyed offspring are considered to be the second generation, and are again crossed with the red-eyed stock, and so forth. The special red-eyed stock is homozygous for the desirable allele A at some other locus, but the white-eyed fly is homozygous for the inferior a allele at that locus. What is the genotype at the eye color locus in the second and subsequent generations?

Name: Often geneticists want to change one allele in an outcrossing organism
Uploaded: 2024-03-20T06:42:55.000Z
Channel: Bartleby
Description: Often geneticists want to change one allele in an outcrossing organism while keeping the rest of the genome the same. For example, they might wish to take a specially designed stock of flies and alter the eye color from red to white. Suppose that the

Human Heredity: Principles and Issues (MindTap Course List)

11th Edition

ISBN:9781305251052

Author:Michael Cummings

Publisher:Michael Cummings

Chapter4: Pedigree Analysis In Human Genetics

Section: Chapter Questions

Problem 10QP: A proband female with an unidentified disease seeks the advice of a genetic counselor before...

See similar textbooks

Similar questions

Often geneticists want to change one allele in an outcrossing organism while keeping the rest of the genome the same. For example, they might wish to take a specially designed stock of flies and alter the eye color from red to white. Suppose that the white-eye allele is dominant, meaning that flies with one or two white-eye alleles will have white eyes. One procedure used is to take a white-eyed fly and cross it with the red-eyed stock. The whiteeyed offspring are then considered to be the first generation, and are crossed with the red-eyed stock. Their white-eyed offspring are considered to be the second generation, and are again crossed with the red-eyed stock, and so forth. The special red-eyed stock is homozygous for the desirable allele A at some other locus, but the white-eyed fly is homozygous for the inferior a allele at that locus. What is the genotype at the eye color locus in the first generation?
Often geneticists want to change one allele in an outcrossing organism while keeping the rest of the genome the same. For example, they might wish to take a specially designed stock of flies and alter the eye color from red to white. Suppose that the white-eye allele is dominant, meaning that flies with one or two white-eye alleles will have white eyes. One procedure used is to take a white-eyed fly and cross it with the red-eyed stock. The whiteeyed offspring are then considered to be the first generation, and are crossed with the red-eyed stock. Their white-eyed offspring are considered to be the second generation, and are again crossed with the red-eyed stock, and so forth. The special red-eyed stock is homozygous for the desirable allele A at some other locus, but the white-eyed fly is homozygous for the inferior a allele at that locus. What fraction of flies will have the a allele (at the second locus) after t generations?
Often geneticists want to change one allele in an outcrossing organism while keeping the rest of the genome the same. For example, they might wish to take a specially designed stock of flies and alter the eye color from red to white. Suppose that the white-eye allele is dominant, meaning that flies with one or two white-eye alleles will have white eyes. One procedure used is to take a white-eyed fly and cross it with the red-eyed stock. The whiteeyed offspring are then considered to be the first generation, and are crossed with the red-eyed stock. Their white-eyed offspring are considered to be the second generation, and are again crossed with the red-eyed stock, and so forth. The special red-eyed stock is homozygous for the desirable allele A at some other locus, but the white-eyed fly is homozygous for the inferior a allele at that locus. How many back-crosses would be necessary to purge 99.9999% of the inferior genes from the white-eyed fly?
Suppose that you are at a party on Friday night, relaxing after your big genetics exam. Someone comes up to you and, hearing that you just finished your genetics exam, says, “What exactly is a gene?” How would you respond? What are the strengths and weaknesses of your definition of a gene?
When you are visiting the local pet store you start talking to them about their Ceti alpha-5 eel colony. They tell you that some eels have red antennas, some have white antennas, and some have pink antennae. Whenever you cross an eel with red antennae to an eel with white antennae you only recover eels with pink antennae. If you assume antennae color is under the control of one gene and you cross two eels with pink antennae what would you predict would be the genotypes and phenotypes of the progeny? How would you explain these results? (Describe why the expected results from ‘a’ would happen.)
Eye colors are passed down through generations, but sometimes genetic variations can lead to surprising results in eye colors (dark eye color, still rocks!?) Some examples are found below. Is there truth behind the following? Provide explanations for your answer. Two parents with blue eyes cannot have a brown-eyed child and vice-versa. Eyes with more than one color stems from parents with two different eye colors. People with violet eyes are mutants. People with red or pinkish eye color can have dark-eyed parents.
This research exploited the principles of Mendelian genetics combined with the MCR technique to genetically manipulate fruit flies. Now, suppose you do a similar experiment. You perform two crosses: one that allows for Mendelian patterns of inheritance, and another that uses MCR with CRISPR-Cas9 to genetically edit the eye color of fruit flies. In fruit flies, the gene for eye color is located on the X chromosome. Red eyes (wild type, w+) are dominant to white eyes (mutant, w-). Let’s see how well you can predict genotype and phenotype ratios resulting from the two crosses. Genetic cross 1 (without MCR): Cross between a white-eyed male and a homozygous red-eyed female. Genetic cross 2 (with MCR): Cross between an MCR-element (carries the CRISPR-Cas9 construct) white-eyed male and a homozygous red-eyed female. Keep in mind, this technology converts a heterozygous genotype to a homozygous recessive genotype. Drag the labels to the table to fill in the genotypic and phenotypic ratios.
Tay-Sachs disease is a rare human disease in which toxic substances accumulate in nerve cells. The recessive allele responsible for the disease is inherited in a simple Mendelian manner. For unknown reasons, the allele is more common in populations of Ashkenazi Jews of eastern Europe. A woman is planning to marry her first cousin, but the couple discovers that their shared grandfather’s sister died in infancy of Tay-Sachs disease.a. Draw the relevant parts of the pedigree, and show all the genotypes as completely as possible. b. What is the probability that the cousins’ first child will have Tay-Sachs disease, assuming that all people who marry into the family are homozygous normal?
Pedigree analysis is a fundamental tool for investigating whether or not a trait is following a Mendelian pattern of inheritance. It can also be used to help identify individuals within a family who may be at risk for the trait. Adam and Sarah, a young couple of Eastern European Jewish ancestry, went to a genetic counselor because they were planning a family and wanted to know what their chances were for having a child with a genetic condition. The genetic counselor took a detailed family history from both of them and discovered several traits in their respective families. Sarahs maternal family history is suggestive of an autosomal dominant pattern of cancer predisposition to breast and ovarian cancer because of the young ages at which her mother and grandmother were diagnosed with their cancers. If a mutant allele that predisposed to breast and ovarian cancer was inherited in Sarahs family, she, her sister, and any of her own future children could be at risk for inheriting this mutation. The counselor told her that genetic testing is available that may help determine if this mutant allele is present in her family members. Adams paternal family history has a very strong pattern of early onset heart disease. An autosomal dominant condition known as familial hypercholesterolemia may be responsible for the large number of deaths from heart disease. As with hereditary breast and ovarian cancer, genetic testing is available to see if Adam carries the mutant allele. Testing will give the couple more information about the chances that their children could inherit this mutation. Adam had a first cousin who died from Tay-Sachs disease (TSD), a fatal autosomal recessive condition most commonly found in people of Eastern European Jewish descent. Because TSD is a recessively inherited disorder, both of his cousins parents must have been heterozygous carriers of the mutant allele. If that is the case, Adams father could be a carrier as well. If Adams father carries the mutant TSD allele, it is possible that Adam inherited this mutation. Because Sarah is also of Eastern European Jewish ancestry, she could also be a carrier of the gene, even though no one in her family has been affected with TSD. If Adam and Sarah are both carriers, each of their children would have a 25% chance of being afflicted with TSD. A simple blood test performed on both Sarah and Adam could determine whether they are carriers of this mutation. Would you decide to have a child if the test results said that you carry the mutation for breast and ovarian cancer? The heart disease mutation? The TSD mutation? The heart disease and the mutant alleles?
Pedigree analysis is a fundamental tool for investigating whether or not a trait is following a Mendelian pattern of inheritance. It can also be used to help identify individuals within a family who may be at risk for the trait. Adam and Sarah, a young couple of Eastern European Jewish ancestry, went to a genetic counselor because they were planning a family and wanted to know what their chances were for having a child with a genetic condition. The genetic counselor took a detailed family history from both of them and discovered several traits in their respective families. Sarahs maternal family history is suggestive of an autosomal dominant pattern of cancer predisposition to breast and ovarian cancer because of the young ages at which her mother and grandmother were diagnosed with their cancers. If a mutant allele that predisposed to breast and ovarian cancer was inherited in Sarahs family, she, her sister, and any of her own future children could be at risk for inheriting this mutation. The counselor told her that genetic testing is available that may help determine if this mutant allele is present in her family members. Adams paternal family history has a very strong pattern of early onset heart disease. An autosomal dominant condition known as familial hypercholesterolemia may be responsible for the large number of deaths from heart disease. As with hereditary breast and ovarian cancer, genetic testing is available to see if Adam carries the mutant allele. Testing will give the couple more information about the chances that their children could inherit this mutation. Adam had a first cousin who died from Tay-Sachs disease (TSD), a fatal autosomal recessive condition most commonly found in people of Eastern European Jewish descent. Because TSD is a recessively inherited disorder, both of his cousins parents must have been heterozygous carriers of the mutant allele. If that is the case, Adams father could be a carrier as well. If Adams father carries the mutant TSD allele, it is possible that Adam inherited this mutation. Because Sarah is also of Eastern European Jewish ancestry, she could also be a carrier of the gene, even though no one in her family has been affected with TSD. If Adam and Sarah are both carriers, each of their children would have a 25% chance of being afflicted with TSD. A simple blood test performed on both Sarah and Adam could determine whether they are carriers of this mutation. Would you want to know the results of the cancer, heart disease, and TSD tests if you were Sarah and Adam? Is it their responsibility as potential parents to gather this type of information before they decide to have a child?
Pedigree analysis is a fundamental tool for investigating whether or not a trait is following a Mendelian pattern of inheritance. It can also be used to help identify individuals within a family who may be at risk for the trait. Adam and Sarah, a young couple of Eastern European Jewish ancestry, went to a genetic counselor because they were planning a family and wanted to know what their chances were for having a child with a genetic condition. The genetic counselor took a detailed family history from both of them and discovered several traits in their respective families. Sarahs maternal family history is suggestive of an autosomal dominant pattern of cancer predisposition to breast and ovarian cancer because of the young ages at which her mother and grandmother were diagnosed with their cancers. If a mutant allele that predisposed to breast and ovarian cancer was inherited in Sarahs family, she, her sister, and any of her own future children could be at risk for inheriting this mutation. The counselor told her that genetic testing is available that may help determine if this mutant allele is present in her family members. Adams paternal family history has a very strong pattern of early onset heart disease. An autosomal dominant condition known as familial hypercholesterolemia may be responsible for the large number of deaths from heart disease. As with hereditary breast and ovarian cancer, genetic testing is available to see if Adam carries the mutant allele. Testing will give the couple more information about the chances that their children could inherit this mutation. Adam had a first cousin who died from Tay-Sachs disease (TSD), a fatal autosomal recessive condition most commonly found in people of Eastern European Jewish descent. Because TSD is a recessively inherited disorder, both of his cousins parents must have been heterozygous carriers of the mutant allele. If that is the case, Adams father could be a carrier as well. If Adams father carries the mutant TSD allele, it is possible that Adam inherited this mutation. Because Sarah is also of Eastern European Jewish ancestry, she could also be a carrier of the gene, even though no one in her family has been affected with TSD. If Adam and Sarah are both carriers, each of their children would have a 25% chance of being afflicted with TSD. A simple blood test performed on both Sarah and Adam could determine whether they are carriers of this mutation. If Sarah carries the mutant cancer allele and Adam carries the mutant heart disease allele, what is the chance that they would have a child who is free of both diseases? Are these good odds?
Hemophilia and color blindness are both recessive conditions caused by genes on the X chromosome. To calculate the recombination frequency between the two genes, you draw a large number of pedigrees that include grandfathers with both hemophilia and color blindness, their daughters (who presumably have one chromosome with two normal alleles and one chromosome with two mutant alleles), and the daughters sons. Analyzing all the pedigrees together shows that 25 grandsons have both color blindness and hemophilia, 24 have neither of the traits, 1 has color blindness only, and 1 has hemophilia only. How many centimorgans (map units) separate the hemophilia locus from the locus for color blindness?