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Solved Exam 2 - General Microbiology | BSCI 223, Exams of Microbiology

University of MarylandMicrobiology
Prof. John Buchner

bsciexam2 Material Type: Exam; Professor: Buchner; Class: GENERAL MICROBIOL; Subject: Biological Sciences Program; University: University of Maryland; Term: Spring 2014;

Typology: Exams

2013/2014

Uploaded on 06/27/2014

gtucker
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Your Name___________________ Your TA’s name________________________
All multiple-choice questions are worth 2 points and have only ONE answer
Other questions will have points indicated. Please be concise with any short answer
questions, limit to 3 sentences or less unless absolutely necessary.
1. Gram-negative Escherichia coli cells grow when plated on agar media containing
penicillin. All of the following could explain this observation EXCEPT
a. Enzyme such as beta lactamase that destroys penicillin
b. Mutation in 30S subunit of ribosome
c. Gene for penicillin resistance
d. R plasmid encoding penicillin resistance
2. In bacteria, RNA polymerase holoenzyme....
a. Binds to a specific sequence in the mRNA
b. Produces both the leading and lagging strand
c. Initiates at a Start Codon
d. Binds to a specific sequence in the DNA
3. All of the following are common to DNA replication in both Prokaryotic and Eukaryotic
cells EXCEPT?
a. Begins at a single universal origin sequence
b. Polymerizes in a 5' to 3' direction
c. Requires 4 dNTPs (A, T, C, G)
d. Has a leading and lagging strand.
4. All of the following describe aspects of bacterial conjugation EXCEPT
a. Can move large fragments of chromosome
b. Utilizes a pilus in the process
c. Formation of a "competent" state
d. Requires direct contact with donor and recipient
5. All of the following are required for site-specific recombination in bacteria EXCEPT
a. Breakage and rejoining of DNA
b. Defined target sequences
c. Large regions of nucleotide similarity
d. Recombinase recognizing exact sequence
6. The antibiotic tetracycline blocks the docking of tRNA onto the 50S subunit of a bacterial
ribosome, but not the 60S subunit of a eukaryotic ribosome. This is an example of
a. Acquired antibiotic resistance
b. Selective toxicity
c. Broad spectrum of activity
d. Synergistic activity
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Your Name ___________________ Your TA’s name________________________ All multiple-choice questions are worth 2 points and have only ONE answer Other questions will have points indicated. Please be concise with any short answer questions, limit to 3 sentences or less unless absolutely necessary.

  1. Gram-negative Escherichia coli cells grow when plated on agar media containing penicillin. All of the following could explain this observation EXCEPT a. Enzyme such as beta lactamase that destroys penicillin b. Mutation in 30S subunit of ribosome c. Gene for penicillin resistance d. R plasmid encoding penicillin resistance
  2. In bacteria, RNA polymerase holoenzyme.... a. Binds to a specific sequence in the mRNA b. Produces both the leading and lagging strand c. Initiates at a Start Codon d. Binds to a specific sequence in the DNA
  3. All of the following are common to DNA replication in both Prokaryotic and Eukaryotic cells EXCEPT? a. Begins at a single universal origin sequence b. Polymerizes in a 5' to 3' direction c. Requires 4 dNTPs (A, T, C, G) d. Has a leading and lagging strand.
  4. All of the following describe aspects of bacterial conjugation EXCEPT a. Can move large fragments of chromosome b. Utilizes a pilus in the process c. Formation of a "competent" state d. Requires direct contact with donor and recipient
  5. All of the following are required for site-specific recombination in bacteria EXCEPT a. Breakage and rejoining of DNA b. Defined target sequences c. Large regions of nucleotide similarity d. Recombinase recognizing exact sequence
  6. The antibiotic tetracycline blocks the docking of tRNA onto the 50S subunit of a bacterial ribosome, but not the 60S subunit of a eukaryotic ribosome. This is an example of a. Acquired antibiotic resistance b. Selective toxicity c. Broad spectrum of activity d. Synergistic activity
  1. The Sigma factor allows a. Bacterial RNA polymerase to form a "core" enzyme b. Bacterial RNA polymerase to bind to eukaryotic promoters c. Bacterial RNA polymerase to bind to specific bacterial promoters d. Bacterial RNA polymerase to elongate RNA transcripts
  2. Spontaneous mutations occur at low frequency as a result of a. Mistakes in DNA replication b. Mistakes in transcription c. Mistakes in translation d. Mistakes in RNA polymerase binding
  3. To determine the minimum inhibitory concentration (MIC) for a given antibiotic, bacterial cultures are a. Serially diluted and exposed to a constant amount of antibiotic b. Observed under the microscope for cell lysis with antibiotic c. Grown in liquid media with serially dilutions of antibiotic d. Exposed to antibiotic discs with constant amount of antibiotic
  4. If E.coli is growing in minimal media + tryptophan, E. coli can shut down the metabolic production of tryptophan by affecting gene transcription of an operon that codes for proteins needed for tryptophan synthesis. What BEST describes the type of regulation likely involved here? a. Activation of the tryptophan operon b. Induction of the tryptophan operon c. Mutation of the tryptophan operon d. Repression of the tryptophan operon
  5. An operon is BEST defined as a. A series of codons that code for multiple proteins b. A segment of DNA that codes for a protein c. Several mRNAs that code for a single protein d. A single mRNA that codes for more than one protein
  6. All of the following are components of a GENE found in DNA EXCEPT a. Promoter b. RBS c. Origin d. Terminator
  7. Penicillin is an antibiotic that interferes with the transpeptidase reaction in bacteria. This indicates that it interferes with which bacterial biosynthetic process? a. Energy metabolism b. Cell wall synthesis c. Protein synthesis d. Transcription
  1. All of the following reagents are important for Polymerase Chain Reaction (PCR) EXCEPT a. oligonucleotide primers b. dNTPs c. restriction enzyme d. thermo-stabile DNA polymerase Answer the next three ( 3 ) questions based on this graph and your knowledge of the lac operon. When E. coli is growing in the presence of both glucose and fructose, the following diauxic growth curve is observed.
  2. What best describes what is likely occurring at time point #1 of the growth curve? a. E. coli is growing on fructose only. b. E. coli is growing on glucose only. c. E. coli is growing on both glucose and fructose. d. E. coli is growing on lactose only.
  3. What best describes what is likely occurring at time point #2 of the growth curve? a. More glucose is being transported into the bacterial cell. b. The genes for fructose utilization are being induced. c. The lac operon is being repressed due to lack of glucose. d. The genes for glucose utilization are being induced.
  4. All of the following conclusions would be reasonable EXCEPT? a. The global regulator CAP/CRP regulates the genes for fructose metabolism. b. E. coli uses glucose preferentially before using fructose. c. Lysed cells provided the X-gal substrate would produce a blue colored product. d. Fructose utilization genes are under Carbon Catabolite Repression. Fructose is exhausted Glucose is exhausted
  1. (4 pts total) List the TWO ( 2 ) types of recombination in bacteria we discussed in lecture. BRIEFLY describe how they occur, whether a protein required, and what the protein recognizes in DNA. Use only 2 - 3 sentences to define each process. Homologous Recombination: RecA required. Allows for recombination of very similar or identical sequences. Site-Specific Recombination: No RecA, but needs Recombinase that recognizes specific sequence and allows recombination to occur.
  2. (6 pts total) The figure below represents a broth dilution method for determining the Minimum Inhibitory Concentration (MIC) of a single antibiotic for three different bacteria (A-C). The darker tubes represent growth and lighter tubes non-growth. a. (2 pts) What is the MIC for organism A? 0.25 μg/ml antibiotic b. (2 pts) Which of the three organisms is the LEAST resistant to the antibiotic being tested? Organism A c. (2 pts) Explain how you got your answer to (b) in 1-2 sentences. Organism A requires the least amount of antibiotic concentration to inhibit the growth compared to Organisms B & C. Could say that the MIC is the lowest for Organism A, which says the same thing.
  1. (14 total pts) Use the following sequence of a strand of bacterial DNA and the genetic code (see last page of exam) to answer the questions below. The underlined bold sequence represents an identified ribosomal binding site (RBS) found in this DNA strand.

5'-C GGAGG CTCATGCGCATACCCAATTTTACGTAATGC-3'

3'-G CCTCC GAGTACGCGTATGGGTTAAAATGCATTACG-5'

5'-C GGAGG CUCAUGCGCAUACCCAAUUUUACGUAAUGC-3'

a. (2 pts) Write the complementary DNA sequence directly underneath the strand above with 5' and 3' indicated. b. (2 pts) Based only on the provided information, label which is the template DNA strand and the sense DNA strand. c. (2 pts) Write the mRNA sequence generated for the entire DNA above (below the complementary strand) with 5' and 3' indicated. d. (2 pts) What is the role of the RBS and in which molecule is it functional (DNA, RNA, or both)? Site where ribosome binds to mRNA to initiate translation e. (2 pts) Write the translated amino acid sequence coded for in the DNA above using 1 or 3 letter abbreviation and the genetic code (see last page). Met-Arg-Iso-Pro-Asn-Phe-Thr or M-R-I-P-N-F-T f. (2 pts) If the nucleotide indicated by the black arrow was changed from an A to a T, what type of mutation would this create related to translation? Missense, introduces a new codon and different amino acid g. (2 pts) Write the translated amino acid sequence resulting from the mutated DNA. Met-Arg-Iso-Pro-Tyr-Phe-Thr or M-R-I-P-Y-F-T

2 8. ( 10 pts total) Below is the diagram of Dr. Kenmore's cloning strategy (PAK2.3) for moving the Methane Monooxygenase ( pmoABC ) operon from M. capsulatus to E. coli for expression in the cow rumen. Briefly (1-2 sentences) describe what basic process is occurring (and its purpose) for each of the ( 5 ) numbered steps. (2 pts each step) a. Step (1): Digest of Vector to remove the lacZ gene b. Step (2): PCR amplification of the pmo operon from M. capsulatus. Could also say it was generated by restriction digest of the chromosome. c. Step (3): Ligation of the vector and pmo operon to form a single recombinant plasmid. d. Step (4): Transformation to introduce the recombinant plasmid into E. coli e. Step (5): Positive selection of the recombinant E. coli with plasmid on antibiotic. Vector' Methane'Monooxygenase' Operon!