Go to the website http://www.cancer.gov and select 'Cancer Types' on the top menu bar. Scroll down to 'Breast Cancer' and click. Select 'Cases & Prevention' from the options. Click 'More information' and select 'BRCA Mutations: Cancer Risk and Genetic Testing'. Use the information on this page to answer the following questions. What features of family history increase the likelihood that a woman will have a harmful mutation of BRCA1 or BRCA2?

The inheritance of certain mutations of BRCA1 can make it much more likely that a woman will develop breast or ovarian cancer in her lifetime. In addition to inheriting a BRCA1 mutation, what else must happen for a woman to develop breast or ovarian cancer?

What are the advantages and disadvantages of using GFP versus lacZ as a reporter gene in mice, C. elegans, and Drosophila?

You conduct a study in which the transcriptional fusion of regulatory sequences of a particular gene with a reporter gene results in relatively uniform expression of the reporter gene in all cells of an organism. A translational fusion with the same gene shows reporter gene expression only in the nucleus of a specific cell type. Discuss some biological causes for the difference in expression patterns of the two transgenes.

Discuss the similarities and differences between forward and reverse genetic approaches, and when you would choose to utilize each of the approaches.

Using the data in Table B, calculate the average number of kilobase (kb) pairs per centimorgan in the six multicellular eukaryotic organisms. How would this information influence strategies to clone genes known only by a mutant phenotype in these organisms?

What are the advantages and disadvantages of using insertion alleles versus alleles generated by chemicals (as in TILLING) in reverse genetic studies?

You have cloned the mouse ortholog of the gene associated with human Huntington disease (HD) and wish to examine its expression in mice. Outline the approaches you might take to examine the temporal and spatial expression pattern at the cellular level.

Diagram the mechanism by which CRISPR–Cas functions in the immune system of bacteria and archaea.

Describe how CRISPR–Cas has been modified to create a genome-editing tool.

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

Discuss the advantages (and possible disadvantages) of the different mutagens in the following table:

You have identified a gene encoding the protein involved in the rate-limiting step in vitamin E biosynthesis. How would you create a transgenic plant producing large quantities of vitamin E in its seeds?

You have identified a recessive mutation that alters bristle patterning in Drosophila and have used recombinant DNA technology to identify a genomic clone that you believe harbors the gene. How would you demonstrate that your gene is on the genomic clone?

The CBF genes of Arabidopsis are induced by exposure of the plants to low temperature. How would you examine the temporal and spatial patterns of expression after induction by low temperature?

The CBF genes of Arabidopsis are induced by exposure of the plants to low temperature. Can you design a method that would reveal these changes in gene expression in a way that a farmer could recognize them by observing plants growing in the field?

When the S. cerevisiae genome was sequenced and surveyed for possible genes, only about 40% of those genes had been previously identified in forward genetic screens. This left about 60% of predicted genes with no known function, leading some to dub the genes fun (function unknown) genes. As an approach to understanding the function of a certain fun gene, you wish to create a loss-of-function allele. How will you accomplish this?

When the S. cerevisiae genome was sequenced and surveyed for possible genes, only about 40% of those genes had been previously identified in forward genetic screens. This left about 60% of predicted genes with no known function, leading some to dub the genes fun (function unknown) genes. You wish to know the physical location of the encoded protein product. How will you obtain such information?

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?

In humans, Duchenne muscular dystrophy is caused by a mutation in the dystrophin gene, which resides on the X chromosome. How would you create a mouse model of this genetic disease?

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?

In enhancer trapping experiments, a minimal promoter and a reporter gene are placed adjacent to the end of a transposon so that genomic enhancers adjacent to the insertion site can act to drive expression of the reporter gene. In a modification of this approach, a series of enhancers and a promoter can be placed at the end of a transposon so that transcription is activated from the transposon into adjacent genomic DNA. What types of mutations do you expect to be induced by such a transposon in a mutagenesis experiment?

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.

Describe the crosses you would perform to determine the number of different genes represented by the 12 mutations.

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?

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

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.

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?

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.

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?

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?