Concept explainers
HOW DO WE KNOW?
In this chapter, we focused on many extensions and modifications of Mendelian principles and ratios. In the process, we encountered many opportunities to consider how this information was acquired. Answer the following fundamental questions:
(a) How were early geneticists able to ascertain inheritance patterns that did not fit typical Mendelian ratios?
(b) How did geneticists determine that inheritance of some
(c) How do we know that specific genes are located on the sexdetermining chromosomes rather than on autosomes?
(d) For genes whose expression seems to be tied to the sex of individuals, how do we know whether a gene is X-linked in contrast to exhibiting sex-limited or sex-influenced inheritance?
(e) How was extranuclear inheritance discovered?
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Essentials of Genetics (9th Edition) - Standalone book
- Which of the following can help explain how continuous variation in a trait can arise from underlying discrete Mendelian genetics (i.e. individual loci at which there are alleles with discrete effects on the phenotype)? O a) Co-dominance b) Meiotic drive c) Blending inheritance d) Multiple loci and the environment can affect expression of a trait e) The germ plasm theoryarrow_forwardAre Mendel’s principles of segregation and independent assortment even relevant today in the age of genomics, when it is possible to sequence an organism’s entire genome and determine all of its genetic information? Why is it important to study these principles, and how can they be used?arrow_forwardIn the P cross between a homozygous, round pea parent and a homozygous, wrinkled pea parent, which of the following did Mendel either observe or subsequently conclude? Question 5 options: A) All somewhat wrinkled peas in the F1 showed blending inheritance. B) All round F1 peas led Mendel to conclude independent assortment. C) The F2 generation revealed some wrinkled peas, indicating the wrinkled pea form was recessive to the round form. D) Two of the above are correct. E) None of the above is correct. Which of the following is not a trait found in the pea plants that Mendel used in his research? Question 3 options: A) The flowers can be pollinated by hand. B) They are self-pollinating. C) The phenotypes studied are caused by more than two alleles in the population. D) Pure genetic lines can be established. E) All but two of the traits studied have genes that occur on distinct chromosomes.arrow_forward
- Question 12 Could a person could carry a harmful allele of an imprintable gene but not show the associated phenotype? O A) ye s B) no Question 16 For which of the following extensions of Mendelian concepts or non-Mendelian concepts would a Punnett square be ineffective for determining the genotypes of offspring from a known cross? O A) maternal effect inheritance B) 'mitochondrial inheritance C) imprinting D) sex-linked inheritance E) all of the above CS Scanned with CamScannerarrow_forwardSeveral members of the family in the pedigree who suffered from a disease are colored in black. Currently deceased members of the family are struck out with a line. Based on the data in the pedigree, propose a Mendelian model that would explain the inheritance of this disease. Explain how the data is consistent with your model. A scientist hypothesizes that a mutation at a single locus is responsible for the pattern of inheritance seen in this pedigree. Explain how a mutation in a gene can arise during meiosis. Describe one strategy organisms use to prevent such mutations from arising.arrow_forwardSeveral members of the family in the pedigree who suffered from a disease are colored in black. Currently deceased members of the family are struck out with a line. Based on the data in the pedigree, propose a Mendelian model that would explain the inheritance of this disease. Explain how the data is consistent with your model. A scientist hypothesizes that a mutation at a single locus is responsible for the pattern of inheritance seen in this pedigree. Explain how a mutation in a gene can arise during meiosis. Describe one strategy organisms use to prevent such mutations from arising. Photo attatchedarrow_forward
- Without referring to the notation used to write the genotypes, how are you able to tell that a gene is inherited by: a. complete dominance (as described by Mendel)? b. incomplete dominance? c. codominance?arrow_forwardIn humans, the genetic disease cystic fibrosis is caused by a recessive allele (a). The normal (healthy) allele is dominant (A). What is the genotype of someone who has cystic fibrosis? What are the two different genotypes that a healthy person could have? If two people were both heterozygous for the cystic fibrosis gene, what fraction of their children would be likely to have this disease? Hint: Draw a Punnett square to figure it out.arrow_forwardBelow is a pedigree of a human genetic disease in which solid color indicates affected individuals. Assume that the disease is caused by a gene that can have the alleles A or a. a) Based on this pedigree, what is the most likely mode of inheritance? b) What is/are the possible genotype/s of person 1? c) What is/are the possible genotype (s) of person 4 ? Explain your answers.arrow_forward
- In the P cross between a homozygous, round pea parent and a homozygous, wrinkled pea parent, which of the following did Mendel either observe or subsequently conclude? A) All somewhat wrinkled peas in the F1 showed blending inheritance. B) All round F1 peas led Mendel to conclude independent assortment. C) The F1 generation consisted of all peas being round and yellow. D) Two of the above are correct. E) None of the above is correct.arrow_forwardPedigree 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?arrow_forwardPedigree 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?arrow_forward
- Human Heredity: Principles and Issues (MindTap Co...BiologyISBN:9781305251052Author:Michael CummingsPublisher:Cengage Learning