Genetics: From Genes to Genomes
Genetics: From Genes to Genomes
6th Edition
ISBN: 9781259700903
Author: Leland Hartwell Dr., Michael L. Goldberg Professor Dr., Janice Fischer, Leroy Hood Dr.
Publisher: McGraw-Hill Education
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Chapter 19, Problem 16P

Suppose a particular gene is required for early development and also later for development of a particular tissue, such as the adult nervous system. By generating a homozygous mutant clone in that tissue of a heterozygote, researchers can circumvent the lethality that would result if the entire animal is homozygous for a loss-of-function mutation in that gene.

A technique called MARCM (Mosaic Analysis with a Repressible Cell Marker) was developed to enable Drosophila geneticists to generate homozygous mutant cell clones that are marked by the presence of a reporter protein such as GFP. Marker expression enables the investigator to observe clearly the mutant phenotype within a clone of mutant cells. This technique relies on a yeast protein called Gal80 that is a negative regulator of the Gal4 protein described previously in Solved Problem II. Gal80 binds to Gal4 and prevents it from activating transcription. The idea of MARCM is that Gal4/UAS -driven GFP expression is blocked by Gal80 throughout the fly, except within the homozygous mutant clone where the Gal80-expressing transgene is lost by mitotic recombination.

a. Diagram the chromosomes and the mitotic crossover that generate a homozygous m mutant clone marked by GFP expression.
b. How could you restrict the clones to the adult nervous system?
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Chapter 19 Solutions

Genetics: From Genes to Genomes

Ch. 19 - Drosophila researchers have collected many strains...Ch. 19 - As an alternative to random mutagenesis,...Ch. 19 - A C. elegans nematode gene called par-1 helps to...Ch. 19 - The molecular identity of the fruit fly rugose...Ch. 19 - To determine the focus of action of boss,...Ch. 19 - Suppose a particular gene is required for early...Ch. 19 - Researchers have exploited Minute mutations in...Ch. 19 - Some ts alleles are temperature sensitive during...Ch. 19 - The following figure shows the temperature-shift...Ch. 19 - A temperature-sensitive allele of the gene...Ch. 19 - Hypomorphic alleles of a pleiotropic gene...Ch. 19 - In addition to the maternal effect genes that...Ch. 19 - The yan gene encodes a transcription factor that...Ch. 19 - Recall from Chapter 17 that in Drosophila, sex...Ch. 19 - a. Explain the difference between maternal...Ch. 19 - In the 1920s, Arthur Boycott, working with the...Ch. 19 - The Drosophila mutant screen shown on the...Ch. 19 - Some genes are required both zygotically and...Ch. 19 - How would a human with a mutation in a maternal...Ch. 19 - One important demonstration that Bicoid is an...Ch. 19 - The hunchback gene contains a 5 transcriptional...Ch. 19 - In flies developing from eggs laid by a...Ch. 19 - Wild-type embryos and mutant embryos lacking the...Ch. 19 - The Drosophila even-skipped eve gene has four...Ch. 19 - In Drosophila with loss-of-function mutations...Ch. 19 - It is crucial to the development of Drosophila...Ch. 19 - In the plant Arabidopsis thaliana, every flower is...
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