Gregor Mendel’s basic principles of inheritance say that each trait is controlled by just one gene with just two alleles, and that each allele is clearly dominant or recessive to the other. However, we now know that many (if not most) traits are not actually inherited according to these rules. Name and describe two other (i.e., non-Mendelian) inheritance patterns, including how each one works, and a give specific example of an actual trait that follows each pattern.

Gregor Mendel’s basic principles of inheritance say that each trait is controlled by just one gene with just two alleles, and that each allele is clearly dominant or recessive to the other. However, we now know that many (if not most) traits are not actually inherited according to these rules. Name and describe two other (i.e., non-Mendelian) inheritance patterns, including how each one works, and a give specific example of an actual trait that follows each pattern.

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 2CS: Pedigree analysis is a fundamental tool for investigating whether or not a trait is following a...

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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?
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?
Mendel's second postulate states: When two different unit factors responsible for a characteristic are found in the same organism, one will dominate and determine the characteristic type. Explain this postulate using modern genetic terms. Be sure to include the following terms in your explanation: dominant, recessive, allele, phenotype, genotype.
Q6. Guinea pigs, which were homozygous for long, black hair were crossed with ones which were homozygous for short, white hair. All the F1 offspring had short, black hair. (a) Using suitable symbols, draw a genetic diagram showing parents genotypes, to explain this result in F1 offspring. (b) Complete the Punnett square to show the results of interbreeding the F1 offspring. Gametes
For Mendelian inheritance, the nuclear genotype (i.e., the allelesfound on chromosomes in the cell nucleus) directly influences anoffspring’s traits. In contrast, for non-Mendelian inheritance patterns, the offspring’s phenotype cannot be reliably predicted solelyfrom its genotype. For the following traits, what do you need toknow to predict the phenotypic outcome?A. Dwarfism due to a mutant Igf2 alleleB. Snail coiling directionC. Leber hereditary optic neuropathy
Mendel's concept of dominance states that in a genotype where two different alleles of a locus are present, only the trait encoded by the dominant allele is observed. Give a molecular explanation for dominance, i.e. explain intracellular molecular events that can result in what we observe as dominance on a phenotypic level. Use the gene that encodes seed shape in peas as an example, where roun(R) is dominant over wrinkled(r), to explain how RR and Rr plants can have the same phenotype.
Mendel's Laws of Inheritance Menders Success Menders approach to the study of heredity was effective for several reasons. Foremost was his choice of experimental subject, the pea plant Pisum sativum. Monohybrid Crosses Mendel began by studying monohybrid crosses— those between parents that differed in a single characteristic. The principle of segregation (Mendel's first law) states that each individual diploid organism possesses two alleles for any particular characteristic. These two alleles segregate (separate) when gametes are formed, and one allele goes into each gamete. Furthermore, the two alleles segregate into gametes in equal proportions.The concept of dominance that, when two different alleles are present in a genotype, only the trait of the dominant allele is observed in the phenotype. Multiple-Loci Crosses Dihybrid Crosses In addition to his work on monohybrid crosses, Mendel also crossed varieties of peas that differed in two characteristics (dihybrid crosses).…
Mendel describes subjecting each of the 34 varieties of peas he obtained to a two-year trial. During this time he let the plants self-fertilize and observed their offspring. What was he looking for, and what was the purpose of doing this two-year trial? Explain what Mendel means when he writes that the 3:1 ratio observed in the first generation from the hybrids "resolves itself" into a ratio of 2:1:1
Mendel’s experiments used plants that had traits which follow simple laws of dominance, segregation, and independent assortment. We have since learned that not all traits follow these simple laws. Give at least three examples of non-Mendelian inheritance patterns and explain how each differs from Mendel’s laws of inheritance.
As you know Mendel’s main contribution to genetics was his proposing a model of particulate inheritance. This discovery contradicted the widely held belief that blending inheritance was the true theory that explained hereditary traits. One advantage that Mendel had in choosing garden peas (Pisum sativum) was that he could either allow the pea flowers on a plant to self-pollinate or he could deliberately cross-pollinate the flowers. For his single locus crosses of pure-breeding lines, he would take the F2 offspring of the dominant phenotype (such as yellow seeds) and ensure that each yellow-seeded plant would self-pollinate. He was able to show that 1/3 of all the yellow-seeded plants in this generation bred true while the other 2/3 of the yellow seeded plants showed segregation. Do you believe that this extra experiment gave additional important evidence for the particulate theory of inheritance or did the offspring from the F1 x F1 cross provide enough evidence of Mendel’s First Law?…
In the previous topic, you learned that Gregor Mendel used Pisum sativum to conceptualize the governing laws of Genetics. In this activity, we will recall how Gregor Mendel utilized the idea of classical breeding to come up with desirable traits. Supposed you have two individual peas. One of the peas is a pure breed with round green seeds while the other has heterozygous round yellow seeds. Supposed a farmer wants to have pure breed peas that have green wrinkled seeds. How are you going to come up with these traits using the two peas that you have? (Note: If the F1 does not include a pure breed green wrinkled seed, you will use the F1 peas for next generation breeding and so on until you have the desired traits. Pure breed means homozygous alleles.) Show the Punnett squares for the cross. You will come up with two or more squares based on how many generations you made.
While traits Mendel worked with all adhered to his principles of inheritance, this is not the norm because phenotypes are typically a combination of both genetic and what other kind of influence?