Skip to main content
Ch. 14 - Analysis of Gene Function via Forward Genetics and Reverse Genetics
Sanders - Genetic Analysis: An Integrated Approach 3rd Edition
Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172Not the one you use?Change textbook
All textbooksSanders 3rd EditionCh. 14 - Analysis of Gene Function via Forward Genetics and Reverse GeneticsProblem 21b
Chapter 14, Problem 21b

The eyes of Drosophila develop from imaginal discs, groups of cells set aside in the fly embryo that differentiate into the adult structures during the pupal stage. Despite their importance in nature, eyes are dispensable for fruit fly life in the laboratory.
What complications might arise from genetic screens targeting an organ that differentiates late in development?

Verified step by step guidance
1
Understand the context: The problem involves genetic screens targeting an organ (the eyes of Drosophila) that differentiates late in development. Genetic screens are used to identify genes involved in specific biological processes, but the timing of organ development can introduce complications.
Consider the timing of gene expression: Genes that are critical for eye development may only be expressed late in the developmental process. This means that mutations affecting these genes might not be detectable until the pupal stage, making it harder to identify them in earlier stages of the screen.
Account for pleiotropy: Some genes involved in eye development may also play roles in earlier developmental processes. Mutations in these genes could cause lethality or other severe phenotypes before the eyes have a chance to develop, complicating the ability to study their specific role in eye differentiation.
Evaluate the dispensability of eyes in the laboratory: Since eyes are not essential for survival in a laboratory setting, mutations affecting eye development might not have a strong selective disadvantage. This could make it easier to isolate and study such mutations, but it also means that the phenotypic effects might be subtle and require careful observation.
Consider technical challenges: Late differentiation of the eyes means that researchers may need to use conditional genetic tools, such as temperature-sensitive alleles or tissue-specific promoters, to study gene function specifically in the eyes without affecting earlier developmental stages. This adds complexity to the experimental design.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
2m
Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Imaginal Discs

Imaginal discs are clusters of undifferentiated cells in the larval stage of Drosophila that later develop into adult structures, including the eyes. These discs are crucial for the proper formation of organs during metamorphosis, as they undergo significant changes to form the adult anatomy. Understanding their role is essential for grasping how late developmental processes can be influenced by genetic factors.
Recommended video:
Guided course
03:07
Supercoiling

Pupal Stage Development

The pupal stage in Drosophila is a transformative phase where the larva undergoes metamorphosis into an adult fly. During this stage, the imaginal discs differentiate into various adult structures, including the eyes. Complications in genetic screens targeting late-differentiating organs may arise because mutations may not manifest until this stage, complicating the identification of genetic functions.
Recommended video:
Guided course
08:30
Genetics of Development

Genetic Screens

Genetic screens are experimental methods used to identify and analyze genes that affect specific traits or developmental processes. In the context of Drosophila, targeting organs that develop late, like the eyes, can lead to challenges in interpreting results, as mutations may not be evident until the later stages of development, potentially obscuring the relationship between genotype and phenotype.
Recommended video:
Guided course
03:45
Descriptive Genetics
Related Practice
Textbook Question

Given your knowledge of the genetic tools for studying Drosophila, outline a method by which you could clone the dunce and rutabaga genes identified by Seymour Benzer's laboratory in the genetic screen.

Textbook Question

How would you design a genetic screen to find genes involved in meiosis?

Textbook Question

Mutations in the CFTR gene result in cystic fibrosis in humans, a condition in which abnormal secretions are present in the lungs, pancreas, and sweat glands. The gene was mapped to a 500-kb region on chromosome 7 containing three candidate genes.

Using your knowledge of the disease symptoms, how would you distinguish between the candidate genes to decide which is most likely to encode the CFTR gene?

Textbook Question

We designed a screen to identify conditional mutants of S. cerevisiae in which the secretory system was defective. Suppose we were successful in identifying 12 mutants.

Based on your knowledge of the genetic tools for studying baker's yeast, how would you clone the genes that are mutated in your respective yeast strains? What is an approach to cloning the human orthologs of the yeast genes?

Textbook Question

Mutations in the CFTR gene result in cystic fibrosis in humans, a condition in which abnormal secretions are present in the lungs, pancreas, and sweat glands. The gene was mapped to a 500-kb region on chromosome 7 containing three candidate genes.

How would you prove that your chosen candidate is the CFTR gene?

Textbook Question

The eyes of Drosophila develop from imaginal discs, groups of cells set aside in the fly embryo that differentiate into the adult structures during the pupal stage. Despite their importance in nature, eyes are dispensable for fruit fly life in the laboratory.

Devise a genetic screen to identify genes directing the development of the fly eye.