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Unformatted text preview: Bios 100 spring 2009 exam #3 For questions 1-5 use the following key: A. E site B. A site C. P site D. Shine-Dalgarno region E. initiation factors 1. The location where mRNA initially binds to the small ribosomal subunit 2. protein that binds the 5’cap of mRNA 3. site from which a tRNA will leave the ribosome after a peptide bond has been formed 4. location where additional tRNAs carrying their amino acids enter the ribosome 5. is also known as the “peptidyl” site 6. Gene expression can be controlled at which of the following levels? A. transcription B. translation C. post-translation (protein activation & inactivation) D. All of the above E. None of the above 7. Transcriptional control is A. slow but efficient B. allows a cell to quickly change which proteins are produced C. provides the most rapid response but is energetically expensive D. not thought to normally play a major role in gene expression E. is always considered to be “positive” within a bacterial cell 8. The lacI gene codes for A. B-galactosidase B. galactoside permease C. a repressor protein D. an enhancer protein E. cAMP 9. When lactose levels are high, A. lactose binds to the lac repressor protein, causing it to become released from DNA and allow the synthesis of B-galactosidase B. it increases levels of cAMP leading to an acceleration of the production of B- galactosidase C. it binds to the operon region of DNA, stimulating the production of galactoside permease D. lactose binds to the lacI gene causing an increase in both B-galactosidase and galactoside permease E. lactose binds to glucose to form more galactose. 10. The region of DNA where the lac repressor protein binds is called the A. promotor region B. Operator C. inhibitor D. Enhancer E. silencer 11. A polycistronic mRNA from a bacterial cell A. codes for only a portion of a single protein B. codes for more than one protein-encoding segment C. contains multiple introns and exons which will be appropriately spliced to form a single protein D. never results in the expression of a functional protein E. codes only for enhancers and silencers 12. The bacterial CAP protein A. binds the CAP binding site near the lac operator & enhances transcription B. strengthens the lac promoter to increase expression C. is regulated by cAMP D. binds to DNA when it is also bound to cAMP E. all of the above 13. In a bacterial cell, when glucose levels are high and lactose levels are low, A. cAMP levels are low B. the lac repressor protein is bound to the operator region inhibiting gene expression C. the CAP binding protein is not bound to DNA D. all of the above E. none of the above...
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This note was uploaded on 03/06/2011 for the course BIOS 100 taught by Professor Kelso during the Spring '07 term at Ill. Chicago.
- Spring '07