Table of contents

1. Introduction to Genetics51m
2. Mendel's Laws of Inheritance3h 37m
3. Extensions to Mendelian Inheritance2h 41m
4. Genetic Mapping and Linkage2h 28m
5. Genetics of Bacteria and Viruses1h 21m
6. Chromosomal Variation1h 48m
7. DNA and Chromosome Structure56m
8. DNA Replication1h 10m
9. Mitosis and Meiosis1h 34m
10. Transcription1h 0m
11. Translation58m
12. Gene Regulation in Prokaryotes1h 19m
13. Gene Regulation in Eukaryotes44m
14. Genetic Control of Development44m
15. Genomes and Genomics1h 50m
16. Transposable Elements47m
17. Mutation, Repair, and Recombination1h 6m
18. Molecular Genetic Tools19m
- Genetic Cloning
  9m
- Methods for Analyzing DNA
  9m
19. Cancer Genetics29m
- Overview of Cancer
  21m
- Cancer Mutations
  7m
20. Quantitative Genetics1h 26m
21. Population Genetics50m
- Hardy Weinberg
  19m
- Allelic Frequency Changes
  31m
22. Evolutionary Genetics29m

14. Genetic Control of Development

Studying the Genetics of Development

Genetics

14. Genetic Control of Development

Studying the Genetics of Development

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2:43 minutes

Problem 25

Textbook Question

How would you conduct a screen to identify recessive mutations in Drosophila that result in embryo lethality? How would you propagate the recessive mutant alleles?

Verified step by step guidance

Begin by designing a genetic screen to identify recessive mutations. Use a mutagen, such as ethyl methanesulfonate (EMS), to induce random mutations in the germline cells of male Drosophila. These males will be the starting point for your screen.

Cross the mutagenized males with wild-type females to produce F1 progeny. The F1 generation will be heterozygous for any induced mutations, as the mutations are recessive and will not be phenotypically expressed in this generation.

To identify recessive mutations, intercross the F1 progeny to produce an F2 generation. In the F2 generation, approximately 25% of the offspring will be homozygous for any given recessive mutation, assuming Mendelian inheritance. These homozygous individuals will express the recessive phenotype, such as embryo lethality.

To propagate the recessive mutant alleles, maintain heterozygous carriers of the mutation. For example, you can cross heterozygous F1 individuals (mutant allele/wild-type allele) with each other or with a balancer stock. Balancer chromosomes are used to prevent recombination and maintain the mutant allele in the population.

Screen the F2 generation for embryo lethality by examining the offspring of heterozygous crosses. Embryos that fail to develop or hatch can be identified as homozygous for the lethal mutation. Maintain the stock by propagating heterozygous carriers to ensure the mutation is preserved for further study.

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Key Concepts

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

Recessive Mutations

Recessive mutations are genetic alterations that only manifest their effects when an individual has two copies of the mutant allele, one inherited from each parent. In Drosophila, these mutations can lead to specific phenotypic traits, such as embryo lethality, which can be identified through careful breeding and observation of offspring.

Drosophila Genetics

Drosophila melanogaster, commonly known as the fruit fly, is a model organism in genetics due to its simple genome, short life cycle, and ease of manipulation. Researchers use Drosophila to study genetic mutations, inheritance patterns, and developmental processes, making it an ideal subject for screening recessive mutations that affect embryonic development.

Propagation of Mutant Alleles

To propagate recessive mutant alleles, researchers typically perform controlled crosses between homozygous mutant flies and wild-type flies. The resulting offspring are then analyzed for the presence of the recessive phenotype, allowing for the establishment of stable lines of mutant alleles that can be further studied or utilized in experiments.

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Related Practice

Textbook Question

Write a short essay based on the concepts related to stages of development that outlines the role of differential transcription, gene control of cell fate, and the role of signaling systems in development.

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Textbook Question

Bird beaks develop from an embryonic group of cells called neural crest cells that are part of the neural tube, which gives rise to the spinal column and related structures. Amazingly, neural crest cells can be surgically transplanted from one embryo to another, even between embryos of different species. When quail neural crest cells were transplanted into duck embryos, the beak of the host embryo developed into a shape similar to that found in quails, creating the 'quck.' Duck cells were recruited in addition to the quail cells to form part of the quck beak. Conversely, when duck neural crest cells were transplanted into quail embryos, the beak of the embryo resembled that of a duck, creating a 'duail,' and quail cells were recruited to form part of the beak. What do these experiments tell you about the autonomy or nonautonomy of the transplanted and host cells during beak development?

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Textbook Question

Carefully distinguish between the terms differentiation and determination. Which phenomenon occurs initially during development?

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Textbook Question

How can you determine whether a particular gene is being transcribed in different cell types?

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Multiple Choice

During early development, human cells determine their differentiated fates based on the environment. What term describes this phenomenon?

The variable gene activity hypothesis states that cell differentiation and determination is controlled through differences in gene activation or inactivation.

If an embryonic cell is damaged in an organism that undergoes mosaic determination, will the offspring produced develop normally or abnormally?

Explain why many developmental genes encode either transcription factors or signaling molecules.

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