Microbiology with Mehari EXAM 3: Powerpoint Questions
In anaplerotic reactions a)Intermediates in a pathway are regenerated. b)Nutrients are imported from the environment. c)Molecules targeted for breakdown are salvaged for anabolism. d)Proteins are synthesized to help cells survive anaerobic conditions.
a) Intermediates in a pathway are regenerated.
PCR consists of three steps, whose order is a)Denaturation, annealing, polymerization b)Denaturation, polymerization, annealing c)Annealing, denaturation, polymerization d)Annealing, polymerization, denaturation e)Polymerization, denaturation, annealing
a) Denaturation, annealing, polymerization
Which drug-resistance mechanism allows bacteria to become resistant to more than one drug at the same time? a) Drug efflux b) Modification of the target c) Inactivation of the drug d) Modification of the drug
a) Drug efflux
Supercoiling in bacteria is typically introduced by an enzyme called DNA a)Gyrase b)Helicase c)Ligase d)Polymerase e)Endonuclease
a) Gyrase
Nitrogen fixation is found only in a few organisms and is tightly regulated because a) Nitrogen fixation is energy-intensive. b) Nitrogenase enzyme is difficult to make. c) Fixed nitrogen is abundant, so nitrogenase is rarely needed. d) Nitrogen is rare in the atmosphere.
a) Nitrogen fixation is energy-intensive.
Archaea resemble eukaryotes in all of the following EXCEPT a)Nuclear membrane b)DNA-packing proteins c)RNA polymerase d)Ribosomal components e)DNA polymerase
a) Nuclear membrane
Why do most fatty acids contain an even number of carbon atoms? a) The priming reaction involves condensation of the acetyl-CoA. b) Fatty acid biosynthesis incorporates malonyl-CoA. c) Fatty acids do not have an even number of carbons. d) It is now easier to add double bonds.
a) The priming reaction involves condensation of the acetyl-CoA.
The sigma factor is directly required for a)Transcription initiation b)Transcription elongation c)Translation initiation d)Translation elongation
a) Transcription initiation
Penicillin was rediscovered by _______, and streptomycin was discovered by _______. a) Fleming; Domagk b) Fleming; Waksman c) Waksman; Fleming d) Waksman; Domagk e) Domagk; Fleming
b) Fleming; Waksman
All of the following are true of transcription initiation EXCEPT a)The RNA polymerase holoenzyme binds. b)GTP hydrolysis catalyzes bubble formation. c)The closed complex becomes the open complex. d)The first rNTP is usually a purine. e)Position +1 marks the start of the gene.
b) GTP hydrolysis catalyzes bubble formation.
Chaperones are proteins that a)Export other proteins out of the cell b)Help other proteins fold properly c)Degrade misfolded proteins d)Bind other proteins to inactivate them
b) Help other proteins fold properly
Which of the following is the reducing cofactor typically used in biosynthesis? a) NADH b) NADPH c) FAD d) FADH2
b) NADPH
The transfer of genetic information from one cell to another is termed _______ transfer. a)vertical b)horizontal c)linear d)oblique e)inverse
b) horizontal
If the sequence of one strand of DNA is 5' TCGATC 3', what is the sequence of the complementary strand? a) 5' CTAGCT 3' b)5' GCTAGC 3' c)5' AGCTAG 3' d)5' GATCGA 3'
c) 5' AGCTAG 3'
Which of these represents a correct order of proteins involved in bacterial DNA replication? a) DnaA → DNA pol III → primase → ligase b) Primase → DNA pol III → DnaA → ligase c) DnaA → primase → DNA pol III → ligase d) Primase → DNA pol III → ligase → DnaA
c) DnaA → primase → DNA pol III → ligase
_______ are protein-degrading organelles found mainly in eukaryotes and archaea. a)Lysosomes b)Proteases c)Proteasomes d)Degradosomes e)Degrons
c) Proteasomes
A bacterial strain exhibiting a mutation in the gene for DNA gyrase would most likely inhibit the activity of what class of antibiotics? a) Metronidazoles b) Tetracyclines c) Quinolones d) Rifampins e) Sulfa drugs
c) Quinolones
All of the following statements about fatty acid biosynthesis are true EXCEPT a)It involves successive condensations of malonyl-ACP. b)A dehydratase is used to generate an unsaturated bond. c)NADH is generally involved in hydrogenation. d)The initial step involves addition of CO2 to acetyl-CoA.
c)NADH is generally involved in hydrogenation.
Which of the following is NOT correct regarding the biosynthesis of purines and pyrimidines? a) Both purines and pyrimidines are built by adding carbon components to ribose 5-phosphate. b) Pyrimidines use uracil as a precursor c) The purine ring is built out of successive additions of amines plus a formyl group. d) Both purines and pyrimidines use inosine monophosphate as a precursor.
d) Both purines and pyrimidines use inosine monophosphate as a precursor.
Quorum sensing is a new approach to antibiotic therapy that works by a) Preventing horizontal transfer of genes b) Stopping bacterial motility c) Binding virulence transcription factors d) Halting bacterial cell-cell communications e) Regulating nutrient uptake to alter metabolism
d) Halting bacterial cell-cell communications
Noncoding sequences make up a large portion of eukaryotic chromosomes. These include a)Exons and introns b)Bacteriophages and plasmids c)Plasmids and introns d)Introns and pseudogenes e)Pseudogenes and bacteriophages
d) Introns and pseudogenes
The level of nitrogen fixation is highest under which of the following conditions? a) High levels of O2 and low levels of NH4+ b) Low levels of O2 and high levels of NH4+ c) High levels of O2 and high levels of NH4+ d) Low levels of O2 and low levels of NH4+
d) Low levels of O2 and low levels of NH4+
The termination of transcription can be caused by which of the following? a)NusA protein b)Stop codon c)Rho factor d)A and C e)All of the above
d) NusA protein AND Rho factor
All of the following drug-target combinations are matched correctly EXCEPT a) Quinolones: inhibit DNA synthesis b) Rifampins: inhibit RNA synthesis c) Gramicidins: disrupt membranes d) Polymyxins: inhibit protein synthesis
d) Polymyxins: inhibit protein synthesis
How many turns of the Calvin cycle does it take to feed one molecule of glyceraldehyde-3-phosphate into the biosynthesis of glucose? a) One b) Two c) Three d) Six e) None of the above
d) Six
Which of the following antifungal-target combinations are correctly matched? a) Azoles: inhibit sterol synthesis b) Polyenes: form pores in membranes c) Griseofulvin: disrupts the mitotic spindle d) Two of the above e) All of the above
e) All of the above
Which of the following drugs inhibit cell wall synthesis? a) Vancomycin b) Penicillin c) Cephalosporins d) Two of the above e) All of the above
e) All of the above
Which of the following pathways is a route for CO2 fixation? a) Reductive acetyl-CoA pathway b) Reductive, or reverse, TCA cycle c) 3-hydroxypropionate cycle d) Two of the above e) All of the above
e) All of the above
Signal sequences in proteins are found a)At the 3′-end of an mRNA molecule b)At the 5′-end of an mRNA molecule c)In the 50S ribosomal subunit d)At the C-terminus of a protein e)At the N-terminus of a protein
e) At the N-terminus of a protein
Antiviral therapy for the human immunodeficiency virus (HIV) usually consists of a protease inhibitor that interferes with which step of the infection cycle? a) Release of newly formed virions by budding b) Fusion of the viral envelope with the host cell membrane c) Binding to the CD4 receptor on human cells d) Insertion of viral DNA into the host cell DNA e) Cleavage of polypeptide chains to make functional HIV proteins
e) Cleavage of polypeptide chains to make functional HIV proteins
Plasmids can be transferred from one bacterium to another via the process of a)Transformation b)Transduction c)Transfection d)Coinfection e)Conjugation
e) Conjugation
Which of the following would provide the best target for a new antibacterial antibiotic? a) Phospholipids in the cell membrane b) Proteins of the glycolysis pathway c) Pyrimidine bases d) Nuclear envelope e) Ribosomes
e) Ribosomes
