Exam: Topics 8-14

Please answer each question fully and in complete sentences. You may use your textbook, class notes, powerpoint slides, and/or homework; if you use other resources, they must be cited properly in a working bibliography (author, article title, journal or book title, date of publication, page numbers) at the end of the exam. Please do not discuss these questions with your classmates: this should be your own work. Each question is worth 10 points. Please be specific in your answers-you have access to textbooks and so your answers are expected to be detailed.

Topic 8: Maintenance of the Genome: DNA Mutation and Repair

Sun exposure can result in direct damage to DNA. What type of DNA damage occurs with sun exposure, and how does this damage specifically affect DNA replication? What process is responsible for its repair in humans? Please explain how this process completely repairs the DNA damage that occurs due to sun exposure. Please be specific in your answer.

Topic 9: Maintenance of the Genome: Recombination

Explain the steps of the homologous recombination process where sequence homology is important. How is the homology identified by the cell? What happens if mismatches exist between recombining strands; how are mismatches dealt with in the cell?

Topic 10: Expression of the Genome: Transcription

Outline the essential features of the three basic phases of transcription, and how each phase can participate in the regulation of gene expression. Which of the three phases is the most common target of regulatory mechanisms? Give examples of how each phase can be specifically regulated.

Topic 11: Expression of the Genome: RNA Splicing

Transcripts can be spliced so that certain pairs of exons are mutually exclusive: that is, the two exons never appear together in the same transcript. Describe fully the three methods that assure mutually exclusive splicing of pairs of exons.

Topic 12: Expression of the Genome: Translation and the Genetic Code

Prokaryotes and eukaryotes are different in the way they initiate translation: how do prokaryotes and eukaryotes differ with respect to the number of open reading frames that are contained in a typical mRNA? Why does this difference make sense in view of the translation initiation strategies used by each type of organism? How might a key regulator turn on a suite of related genes in both prokaryotic and eukaryotic cells?

Topic 13: Gene Regulation: Prokaryotes

When glucose is present, the lac genes in the lac operon are not fully expressed, even in the presence of the allolactose inducer for lac operon expression. This is called catabolite repression, and glucose becomes the catabolite repressor. Why does it make biological sense to have the lactose operon

a. under negative control by Lac repressor, inducible only by allolactose

b. controlled by catabolite repression in the presence or absence of allolactose

c. controlled by the same CAP protein that is necessary to turn on several sugar operons (including the arabinose, lactose, maltose, and galactose operons)?

Topic 14: Gene Regulation: Eukaryotes

Describe the physical characteristics and individual components of a typical eukaryotic transcriptional activation region. Explain how each component is directly involved in the mechanism of activation of transcription.

Text Book: Molecular Biology of the Gene by James D. Watson, Alexander Gann, Tania A. Baker, Michael Levine, Stephen P. Bell, Richard Losick and Stephen C. Harrison.