Textbook Question
Provide a definition and an example for each of the following terms:
concordance of twin pairs
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Ch. 4 - Gene Interaction
Chapter 4, Problem 7
Provide a definition and an example for each of the following terms:
quantitative trait locus
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A Quantitative Trait Locus (QTL) is a section of DNA (a locus) that correlates with variation in a quantitative trait in the phenotype of a population of organisms.
Quantitative traits are those that are measured on a continuous scale, such as height, weight, or blood pressure, and are typically influenced by multiple genes and environmental factors.
QTLs are identified through statistical analysis of the association between genetic markers and phenotypic variation in a population.
An example of a QTL is a region on a chromosome that is associated with variation in plant height in a population of corn plants.
Researchers use techniques like linkage mapping or genome-wide association studies (GWAS) to locate QTLs and understand their contribution to the trait of interest.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Quantitative Trait Locus (QTL)
A Quantitative Trait Locus (QTL) is a specific region of DNA that is associated with a particular quantitative trait, which is a measurable phenotype that varies continuously, such as height or weight. QTLs are identified through statistical analysis of phenotypic data and genetic markers, allowing researchers to link genetic variation to observable traits.
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Phenotype
Phenotype refers to the observable characteristics or traits of an organism, which result from the interaction of its genotype (genetic makeup) with the environment. Examples of phenotypes include physical attributes like color, size, and shape, as well as behavioral traits. Understanding phenotypes is crucial for studying how QTLs influence specific traits.
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Genetic Markers
Genetic markers are specific sequences in the genome that can be used to identify individuals or species and track inheritance patterns. They serve as reference points in genetic mapping and are essential for locating QTLs. Common types of genetic markers include single nucleotide polymorphisms (SNPs) and microsatellites, which help in associating genetic variations with phenotypic traits.
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Related Practice
Textbook Question
Provide a definition and an example for each of the following terms:
multifactorial inheritance
206
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Textbook Question
Provide a definition and an example for each of the following terms:
polygenic inheritance
286
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Textbook Question
Provide a definition and an example for each of the following terms:
threshold trait
205
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Textbook Question
Two genes interact to produce various phenotypic ratios among F₂ progeny of a dihybrid cross. Design a different pathway explaining each of the F₂ ratios below, using hypothetical genes R and T and assuming that the dominant allele at each locus catalyzes a different reaction or performs an action leading to pigment production. The recessive allele at each locus is null (loss-of-function). Begin each pathway with a colorless precursor that produces a white or albino phenotype if it is unmodified. The ratios are for F₂ progeny produced by crossing wild-type F₁ organisms with the genotype RrTt.
9/16 dark blue : 6/16 light blue : 1/16 white
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Textbook Question
Two genes interact to produce various phenotypic ratios among F₂ progeny of a dihybrid cross. Design a different pathway explaining each of the F₂ ratios below, using hypothetical genes R and T and assuming that the dominant allele at each locus catalyzes a different reaction or performs an action leading to pigment production. The recessive allele at each locus is null (loss-of-function). Begin each pathway with a colorless precursor that produces a white or albino phenotype if it is unmodified. The ratios are for F₂ progeny produced by crossing wild-type F₁ organisms with the genotype RrTt.
12/16 white : 3/16 green : 1/16 yellow
221
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