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Ch. 18 - Developmental Genetics
Sanders - Genetic Analysis: An Integrated Approach 3rd Edition
Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172당신이 사용하는 게 아니라요?교과서 변경
모든 교과서Sanders 3rd EditionCh. 18 - Developmental Genetics문제 16b
18장, 문제 16b

The pair-rule gene fushi tarazu is expressed in the seven even-numbered parasegments during Drosophila embryogenesis. In contrast, the segment polarity gene engrailed is expressed in the anterior part of each of the 14 parasegments. Since both genes are active at similar times and places during development, it is possible that the expression of one gene is required for the expression of the other. This can be tested by examining the expression of the genes in a mutant background—for example, looking at fushi tarazu expression in an engrailed mutant background, and vice versa. Based on your prediction, can you predict the phenotype of the fushi tarazu and engrailed double mutant?

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Step 1: Understand the roles of the fushi tarazu and engrailed genes. Fushi tarazu is a pair-rule gene responsible for defining the even-numbered parasegments during Drosophila embryogenesis, while engrailed is a segment polarity gene that defines the anterior part of each parasegment. Both genes are critical for proper segmentation during development.
Step 2: Analyze the relationship between the two genes. Since both genes are expressed at similar times and places during development, it is hypothesized that the expression of one gene may depend on the other. This dependency can be tested by examining their expression in mutant backgrounds.
Step 3: Predict the phenotype of a single mutant. In a fushi tarazu mutant, the even-numbered parasegments would likely fail to form, leading to disrupted segmentation. In an engrailed mutant, the anterior part of each parasegment would likely fail to form, also causing segmentation defects.
Step 4: Consider the double mutant scenario. If both fushi tarazu and engrailed are non-functional, the segmentation process would be severely disrupted. The phenotype would likely involve a complete loss of proper parasegment formation, as neither the pair-rule nor the segment polarity functions are intact.
Step 5: Reflect on the developmental consequences. The double mutant would likely result in a severely abnormal Drosophila embryo, with a failure to establish the segmented body plan that is essential for normal development. This prediction aligns with the idea that both genes are critical for segmentation and their loss would have additive effects.

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주요 개념

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Gene Expression in Development

Gene expression refers to the process by which information from a gene is used to synthesize functional gene products, typically proteins. In developmental biology, specific genes are activated at certain times and locations, influencing the formation of structures and patterns in an organism. Understanding how genes like fushi tarazu and engrailed are expressed during Drosophila embryogenesis is crucial for predicting phenotypic outcomes in mutants.
추천 영상:
가이드 코스
02:09
Penetrance and Expressivity

Mutant Analysis

Mutant analysis involves studying organisms with specific gene mutations to understand the function of those genes. By examining the expression of genes in mutant backgrounds, researchers can infer the relationships and dependencies between different genes. In this case, analyzing fushi tarazu expression in an engrailed mutant helps determine if the activity of one gene is necessary for the expression of the other.
추천 영상:
가이드 코스
02:48
Chi Square Analysis

Phenotypic Prediction

Phenotypic prediction is the process of forecasting the observable traits or characteristics of an organism based on its genetic makeup. In the context of double mutants, such as fushi tarazu and engrailed, predicting the phenotype requires understanding how the loss of function in both genes may interact and affect developmental processes. This prediction can reveal insights into the genetic pathways that govern segmentation in Drosophila.
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가이드 코스
10:48
Mutations and Phenotypes
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교과서 질문

The pair-rule gene fushi tarazu is expressed in the seven even-numbered parasegments during Drosophila embryogenesis. In contrast, the segment polarity gene engrailed is expressed in the anterior part of each of the 14 parasegments. Since both genes are active at similar times and places during development, it is possible that the expression of one gene is required for the expression of the other. This can be tested by examining expression of the genes in a mutant background—for example, looking at fushi tarazu expression in an engrailed mutant background, and vice versa. Given the hierarchy of gene action during Drosophila embryogenesis, what might you predict to be the result of these experiments?

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