How would you perform a genetic screen to identify genes directing Drosophila wing development? Once you have a collection of wing-development mutants, how would you analyze your mutagenesis to learn how many genes are represented and how many alleles of each gene? How would you discover whether the genes act in the same or different pathways, and if in the same pathway, how do you discover the order in which they act? How would you clone the genes?

Discuss the advantages (and possible disadvantages) of the different approaches to reverse genetics.

Translational fusions between a protein of interest and a reporter protein are used to determine the subcellular location of proteins in vivo. However, fusion to a reporter protein sometimes renders the protein of interest nonfunctional because the addition of the reporter protein interferes with proper protein folding, enzymatic activity, or protein–protein interactions. You have constructed a fusion between your protein of interest and a reporter gene. How will you show that the fusion protein retains its normal biological function?

A 2-kb fragment of E. coli DNA contains the complete sequence of a gene for which transcription is terminated by the rho protein. The fragment contains the complete promoter sequence as well as the terminator region of the gene. The cloned fragment is examined by band shift assay (see Research Technique 8.1). Each lane of a single electrophoresis gel contains the 2-kb cloned fragment under the following conditions:Lane 1: 2-kb fragment aloneLane 2: 2-kb fragment plus the core enzymeLane 3: 2-kb fragment plus the RNA polymerase holoenzymeLane 4: 2-kb fragment plus rho proteinExplain the relative positions of bands in lanes 1 and 4.

A 3.5-kb segment of DNA containing the complete sequence of a mouse gene is available. The DNA segment contains the promoter sequence and extends beyond the polyadenylation site of the gene. The DNA is studied by band shift assay (see Research Technique 8.1), and the following gel bands are observed.Match these conditions to a specific lane of the gel.3.5-kb fragment plus TFIIB and TFIID

A 3.5-kb segment of DNA containing the complete sequence of a mouse gene is available. The DNA segment contains the promoter sequence and extends beyond the polyadenylation site of the gene. The DNA is studied by band shift assay (see Research Technique 8.1), and the following gel bands are observed.Match these conditions to a specific lane of the gel.3.5-kb fragment plus TFIIB, TFIID, TFIIF, and RNA polymerase II