Exam 15: Genetic Analysis of Cellular Processes

Components and analogs of the lac operon are used by researchers as experimental tools. Match the molecule with its activity. -IPTG

Many receptor tyrosine kinase genes are essential, making it difficult to assess the function of such genes. How did researchers get around this problem when examining the roles of the sev gene?

Fill in the blank. Another name for a genetic screen is a ______ screen.

Fill in the blank. Receptor tyrosine kinases add a _______ to specific tyrosine residues in target proteins

Match the missing words in the following phrase. In the Nüsslein-Volhard and Wieschaus experiment, embryos lacking in a contiguous region across segments had mutations in [A] genes. Mutants lacking every other segment had defects in [B] genes. Mutants that had alterations in specific regions of the embryo were defective in [C] genes. Finally, mutants that exchanged the identity of a region for that of another region were defective in [D] genes.

During investigation of the lac operon, Jacob and Monod found that mutations in the same gene did not always lead to the same phenotypic outcome. For example, some mutations in the lacI gene led to constitutive lactose breakdown, whereas other mutations led to an inability to ferment lactose under any conditions. Which of the following statements are true about lacI^s mutations? Please select all that apply.

Which characteristic of Drosophila melanogaster was exploited in the screen that led to the discovery of the ras pathway?

A diagram of the mutagenesis and crossing strategy used by Nüsslein-Volhard and Wieschaus to generate and maintain segmentation mutants is shown. Male flies were exposed to EMS (a mutagen) and mated to a non-mutagenized female. How did the researchers ensure that the offspring of Cross B (i.e., the offspring seen in generation C in the diagram) were heterozygotes that carried a mutagenized chromosome? Please select all that apply.

Components and analogs of the lac operon are used by researchers as experimental tools. Match the molecule with its activity. -β-galactosidase

Fill in the blank. In the lac operon, cAMP-CAP is produced and binds to the CAP binding site when ____ is low

Which of the following are advantages of random mutagenesis compared to targeted mutagenesis? Please select all that apply.

Match the missing words in the following phrase. Experiments showed that cell cycle mutants stalled at specific points in the cycle. Mutants could be classified in relation to recognizable steps called [A] events. Cells with a particular mutation stalled at [B] point in the cell cycle, despite the individual cells starting the experiment at [C] point in the cycle. This indicated that the gene product was critical at a specific point in the cycle but was not always needed throughout the cycle. These critical points were termed the [D] point for each gene.

Which of the following features of genetic screens was not key to the success of Beadle and Tatum's early Neurospora crassa experiments with nutritional auxotrophs?

Which of the following methods have been used to generate libraries of disrupted genes for an organism? Please select all that apply.

The ras gene is a major component of which sort of pathway?

Components and analogs of the lac operon are used by researchers as experimental tools. Match the molecule with its activity. -X-gal

Forward genetics involves disruption of a known gene to see what phenotypes will be produced. Reverse genetics involves introducing random mutations and examining the resultant phenotypes to discover the causative gene.

Fill in the blank. In genetic screens, the chance of discovering a novel gene decreases as the screen proceeds. When the chance of finding a new gene is very low and the effort expended to discover a new gene is not justifiable, the screen has been _________.

Hartwell and colleagues used the yeast Saccharomyces cerevisiae to examine the cell cycle. However, most cell cycle mutants are lethal. How did the researchers get around this problem in their experiments?

To identify genes in the sev pathway, sev mutants were further mutagenized and the phenotype examined. Mutations that alleviate the sev phenotype are called suppressor mutations and mutations that exacerbate the sev phenotype are called synthetic enhancer mutations.