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Unformatted text preview: BioS 115 Exam 3A _______________________ Genetics November 17, 2010 Name Page 1 of 5 IMPORTANT: Mak e s ur e you hav e your s c an t ron . Wri t e t h e e xam v e r s ion (A , B , C) on t h e an s w e r c ard! Wri t e your nam e on t hi s s h ee t . Th e r e ar e 45 qu e st ion s on t h e e xam , wor t h a t o t al of 90 poin ts . Pl e a s e r e ad t h e qu e st ion s c ar e fully . Alway s c hoo s e t h e MOST CORRECT an s w e r . Mark an s w e r s on t h e e xam s h ee t F IRST . Wh e n you ar e c onfid e n t t ha t your an s w e r s ar e c orr ec t , mark t h e s c an t ron s h ee t u s ing a No . 2 p e n c il . Thi s st ra t e gy avoid s e ra s ur e s on t h e s c an t ron s h ee t . Bo t h t h e e xam and s c an t ron s h ee ts will b e c oll ec t e d . 1. What type of proteins can bind to double stranded DNA in a sequence-specific manner (involving direct contacts to bases in the DNA helix? A) restriction enzymes such as Nhe I and Sfi I B) Zinc-finger transcription factors C) TATA-box binding protein D) Helix-turn-helix transcription factors E) all of the above 2. In the la c operon in E . c oli , a nonsense mutation in the ________ gene will result in a loss of -galactosidase activity in the cell. A) la c Z B) la c I C) la c Y D) Both A and B E) All of these The following schematic shows the structure of the la c op e ron . Name the components numbered 3-6. 3. A) inducer B) co-repressor C) operator D) promoter 4. A) operator B) enhancer C) centromer D) promoter 5. A) enhancer B) terminator C) structural genes D) promoter 6. A) inducer B) repressor C) enhancer D) ribosome 7. A) the lac operon is shown in its off-state B) the lac operon is shown in its inducible state C) A and B are true 8. In presence of the lac repressor (lacI) and absence of an inducer, RNA polymerase is not able to activate expression of lac mRNA because: A) the RNA polymerase binding site on the promoter is not accessible B) the repressor is unable to bind to the promoter C) the inducer is unable to bind to the operator 9. You have isolated a protein ZETA that binds to DNA in the region upstream of the promoter sequence of the SyS gene. If ZETA is a positive regulator, which one of the following would be true? A) Loss-of-function mutations in the ZETA gene would cause constitutive expression of SYS. B) Loss-of-function mutations in the ZETA gene would result in little or no expression of SYS. C) Mutations that alter the DNA sequence to which ZETA binds result in little or no expression of SYS. D) Both statements B and C are true. z y a 3 4 5 6 i mRNA BioS 115 Exam 3A _______________________ Genetics November 17, 2010 Name Page 2 of 5 10. A transcriptional enhancer site can be located far upstream of the promoter sequence for the gene it activates. How then can binding of a transcription activator protein to such an enhancer activate transcription at the downstream promoter?...
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This note was uploaded on 10/03/2011 for the course CHEM 31 taught by Professor Roberts during the Fall '10 term at Lehigh University .
- Fall '10