Microbial genetics biol518 exam 4 fall 2010 name 8

Info icon This preview shows pages 2–4. Sign up to view the full content.

View Full Document Right Arrow Icon
Microbial Genetics BIOL518 Exam 4 - Fall 2010 Name_____________________________________________________________________ 8: During the stationary phase of bacterial growth A: expression of genes that encode virulence factors can be induced B: the associated transcriptional response is almost identical to that of bacteria grown in the absence of glucose but the presence of galactose C: the transcriptional response is also called a general stress response D: the master regulator of the transcriptional response observed is an alternative sigma factor termed Sigma S (RpoS) 9: Which of the following contribute to the absence of transcription of heat shock genes (genes that are transcribed by RNA polymerase containing RpoH σ 32 ) when E. coli cells have NOT been exposed to elevated (high) temperatures? A: There is no transcription of the gene encoding σ 32 under these conditions. B: Binding of DnaK to σ 32 blocks the ability of σ 32 to interact with RNA polymerase core enzyme (or to cognate promoters). C: Much of the σ 32 protein will be degraded by the protease FtsH. D: The mRNA of the σ 32 transcript folds into a structure that reduces its translation. 10: When low ammonia (NH 3 ) concentrations are available in an E. coli cell: A: more of the enzyme glutamine synthetase (GlnA) is needed than under high ammonia conditions. B: NtrB phosphorylates NtrC, and therefore the NtrC~P concentration will be high. C: Ntr B~P binds to DNA sites upstream of the glnA operon and activates transcription. D: NtrC~P contacts RNAP containing sigma54 11: When there is essentially no free tryptophan in an E. coli cell, but the majority of the appropriate tRNA is charged with tryptophan: A: A ribosome translating the trpEDCBA operon leader peptide will stall at the stop codon. B: A stalled ribosome will cover regions 1 and 2 of the trpEDCBA operon leader region. C: Regions 3 and 4 of the trpEDCBA operon leader will form a stem loop. D: Transcription of the trpEDCBA operon will terminate before it reaches trpE . 12: The helical repeat experiment with araBAD : A: provided evidence that positive regulation of araBAD involves DNA looping. B: provided evidence that negative regulation of araBAD involves DNA looping. C: showed that insertion of 5, 15 and 25 bp between araO2 and araI allowed nearly normal regulation. D: showed that insertion of 10, 20, and 30 bp between araO2 and araI allowed nearly normal regulation. 13: The glutamine synthetase enzyme, encoded by the glnA gene: A: catalyzes the reaction: (ammonia) NH 3 + glutamate ---> glutamine. B: is synthesized at a higher rate by sigma 54/N under low NH 3 conditions. C: is responsible for the vast majority of ammonia assimilation under low ammonia conditions. D: is encoded in an operon that also encodes the regulatory proteins of the operon. Page 2, v1
Image of page 2

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Microbial Genetics BIOL518 Exam 4 - Fall 2010 Name_____________________________________________________________________ Long Answer . For each question give a thorough and specific answer. Well-labeled diagrams, with sufficient text to explain them are highly encouraged when appropriate. The point value of each question is given in parentheses. (24 points total) 14: Fully describe the regulation of the E. coli araBAD operon by the AraC protein only (ie - if there is a second regulator of araBAD expression, you do NOT need to describe its role). Be sure to describe what AraC does both in the presence and the absence of arabinose.
Image of page 3
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern