Lecture 7 Flashcards
Supercoiling is important for DNA structure because ________.
(A) It holds together the antiparallel strands of DNA in the double helix
(B) It provides energy for transcription
(C) It condenses the DNA so that it can fit inside the cell
(D) It prevents RNA from pairing with DNA in the double helix
(E) None of the above
(C) It condenses the DNA so that it can fit inside the cell
Genes that encoded for polymerases, gyrases, ribosomal proteins, and other proteins
essential to replication, transcription, and translation are present on ________.
(A) Chromosomes
(B) Plasmids
(C) Chromosomes and plasmids
(D) Neither chromosomes nor plasmids
(E) None of the above
(A) Chromosomes
In Bacteria, a chromosome can be distinguished from a plasmid, because a chromosome
is a genetic element that ________.
(A) Is circular
(B) Is linear
(C) Encodes for essential functional genes
(D) Encodes for non-essential (“luxury”) genes
(E) None of the above
(C) Encodes for essential functional genes
________ is an essential enzyme in DNA replication that unwinds the double-stranded
DNA, creating a ________ and exposing single-stranded DNA templates.
(A) DNA ligase / replication fork
(B) DNA gyrase / transcription bubble
(C) DNA helicase / replication fork
(D) DNA polymerase / transcription bubble
(E) None of the above
(C) DNA helicase / replication fork
During DNA replication, the enzyme ________ synthesizes short strands of RNA
(primers) that serve as a starting point for DNA elongation.
(A) Primase
(B) Polymerase
(C) Gyrase
(D) Helicase
(E) None of the above
(A) Primase
check this
Polymerase chain reaction (PCR) is a method of DNA replication in vitro that uses
______ instead of the enzyme ______ to denature double-stranded DNA and expose
single-stranded DNA templates.
(A) Heat / DNA helicase
(B) Primers / DNA helicase
(C) Heat / DNA polymerase
(D) Primers / DNA polymerase
E) None of the above
(A) Heat / DNA helicase
During the ________ step of the polymerase chain reaction (PCR), the reaction mixture is
heated to 72ºC to allow the binding of the ________.
(A) Extension / DNA polymerase
(B) Extension / primers
(C) Annealing / DNA polymerase
(D) Annealing / primers
(E) None of the above
(A) Extension / DNA polymerase
During the ________ step of the polymerase chain reaction (PCR), the reaction mixture is
cooled to 55ºC to allow the binding of ________.
(A) Denaturing / primers
(B) Annealing / DNA polymerase
(C) Annealing / primers
(D) Extension / DNA polymerase
(E) None of the above
(C) Annealing / primers
The specificity of PCR amplification is determined by which ingredient in the reaction
mixture?
(A) DNA helicase
(B) DNA polymerase
(C) Nucleotides
(D) Primers
(E) None of the above
(D) Primers
________ result from hydrogen bonds that form between nucleotides in the SAME strand
of an RNA molecule.
(A) Primary structures
(B) Secondary structures
(C) Tertiary structures
(D) Quaternary structures
(E) None of the above
(B) Secondary structures
In the process of transcription, promoters are specific sequences of ________ that are
recognized by ________.
(A) DNA / DNA polymerase
(B) RNA / DNA polymerase
(C) DNA / sigma factors
(D) RNA / ribosomes
(E) None of the above
(C) DNA / sigma factors
The structure of RNA polymerase in Archaea is ______.
(A) More similar to Eukaryotes than to other Prokaryotes (Bacteria)
(B) More similar to other Prokaryotes (Bacteria) than to Eukaryotes
(C) Simpler (fewer subunits) than bacterial RNA polymerase
(D) Simpler (fewer subunits) than eukaryotic RNA polymerase
(E) None of the above
(A) More similar to Eukaryotes than to other Prokaryotes (Bacteria)
Many pharmaceutical drugs specifically inhibit transcription in Bacteria but not Archaea.
Why would drugs that inhibit transcription only affect Bacteria and not Archaea even
though they are both prokaryotes?
(A) Bacteria lack a nucleus
(B) Archaea lack operons
(C) Archaea have ribosomes that are more similar to Eukaryotes than Bacteria
(D) Archaea have RNA polymerases that are more similar to Eukaryotes than Bacteria
(E) None of the above
(D) Archaea have RNA polymerases that are more similar to Eukaryotes than Bacteria
Transfer RNA molecules ________.
(A) Function to transfer ribonucleotides to RNA polymerase during transcription
(B) Function to transfer the correct amino acids to the ribosome during translation
(C) Contain codons that bind to ribosomes during translation
(D) Are only present in the nucleus or eukaryotes
(E) None of the above
(C) Contain codons that bind to ribosomes during translation
The codon on the ________ matches with the anticodon on the ________ to direct the
addition of the correct amino acid to the growing polypeptide chain.
(A) mRNA / tRNA
(B) tRNA / mRNA
(C) DNA / mRNA
(D) tRNA / rRNA
(E) None of the above
(A) mRNA / tRNA
Translation is terminated by ________ that recognize the stop codon and release the
newly synthesized protein.
(A) Inverted repeats
(B) Molecular chaperones
(C) Release factors
(D) Ribosome-release sequences
(E) None of the above
(C) Release factors
You are studying the expression of a bacterial gene coding for a new protein. By
randomly mutating the DNA sequence directly upstream of the start codon of the gene,
you create a mutant that produces the SAME amount of mRNA, but very FEW proteins.
You conclude that the DNA sequence that you mutated is MOST likely a ________.
(A) Promoter region
(B) Ribosome-binding site
(C) Transcription termination sequence
(D) Non-coding DNA region
(E) None of the above
(A) Promoter region
________ is a mechanism by which bacteria assess population density, producing internal
signal molecules called autoinducers.
(A) Autophosphorylation
(B) Response regulation
(C) Signal transduction
(D) Quorum sensing
(E) None of the above
(D) Quorum sensing
Aliivibrio fischeri is a symbiotic bacterium whose bioluminescence is controlled by
quorum sensing. During a growth curve of A. fischeri, when would you expect to see the
strongest bioluminescence?
(A) Lag phase
(B) Early to middle log phase
(C) Late log to early stationary phase
(D) Death phase
(E) None of the above
(B) Early to middle log phase
A triplet of bases on an mRNA molecule is known as a(n) ________.
(A) Amino acid
(B) Anticodon
(C) Codon
(D) Ribosome-binding sequence
(E) None of the above
(C) Codon
alpha-helices and beta-sheets are formed by hydrogen bonds between amino acids and are
examples of ________ structure in proteins.
(A) Primary
(B) Secondary
(C) Tertiary
(D) Quaternary
(E) None of the above
(B) Secondary
Which type of protein would exhibit the MOST stability?
(A) A protein with more alpha-helices than beta-sheets
(B) A protein with more beta-sheets than alpha-helices
(C) A protein with equal amounts of beta-sheets and alpha-helices
(D) A protein with only beta-sheets
(E) None of the above
(A) A protein with more α-helices than β-sheets
Hydrophobic interactions and disulfide bonds aid in the formation of ________ structure
in proteins.
(A) Primary
(B) Secondary
(C) Tertiary
(D) Quaternary
(E) None of the above
(C) Tertiary
________ assist in the proper folding of newly synthesized and partially denatured proteins, ensuring proper protein structure and function.
(A) tRNA
(B) Ribosomes
(C) Release factors
(D) Molecular chaperones
(E) None of the above
D) Molecular chaperones
A mutation that restores the function of gene is called a ______ mutation.
reversion
mutations that result from inaccurate base pairing by DNA polymerase during DNA replication are called ____ mutations.
spontaneous
______ are chemical mutagens that inserts themselves between the base pairs of DNA and cause _____ mutations
intercalating agents/ frame shift
the ames test detects chemical mutagens by using ____ bacteria to quantify reversion mutations
auxotrophic
horizontally transmitted DNA can be inserted into bacterial chromosomes by _____
homologous recombinations
the uptake of DNA released from a cell (“naked” DNA) is called _____, while the transfer of DNA with direct cell-to-cell contact is called _____.
transformation/ conjugation
the uptake of naked DNA from the environment can be dangerous for bacterial cells. one mechanism to ensure the naked DNA from related cells is acquired is ______
Induced competency, where cells only uptake DNA when population density is high
The F (Fertility) plasmid contains a set of genes that encode for _______ proteins that are essential conjugative transfer of DNA
Pili
______ is the enzyme that mediates the transfer of transposable elements
transposase
insertion sequences differ from transposons because they _____.
contain a single gene that codes for transposase
when packaged in the vision, the complete complex of nucleic acid and protein is known as the _____.
nucleocapsid
animals are most commonly infected by ______ viruses
enveloped
for bacteriophages and animal viruses ______ is the step in the viral life cycle that determines host cell or tissue specificity
attachment
viral proteins are categorized as early, middle and late. late proteins typically necessary for ______.
production of viral capsid
a virus that kills its host cell is said to be _____
lytic (virulent)
The attachment stage of viral infection is nearly impossible to prevent because
viruses target surface receptors that cells require to survive
bacteria produce restriction endonucleases to destroy viral DNA that enters the cell. These enzymes only digest viral DNA because the ______ DNA is ______.
host/ methylated
the function of the CRISPR ( clustered, regularly interspaced, short, palindromic repeats) system is to ______.
recognize and destroy viral nucleic acids in the cells
infections proteins are called _____ and “replicate” by______
prions/ misfiling proteins upon contact
in which areas of the human body is the resident micro biome not found
internal organs
antimicrobial compounds naturally found on human skin include
peptides
bacterial biofilms grow on tooth surfaces are called _______. When these biofilms include lactic acid bacteria, acidic by-products of their fermentation break down tooth enamel, causing ______.
dental plaque / dental caries
few microorganisms can survive in the human stomach due to its _____
low pH
the consequences of disrupting the resident GI micro biome of the human body include_____
diarrhea
impaired vitamin synthesis
enhanced pathogen colonization
the presence of lactic acid bacteria in the vaginal micro biome is ______ because they ______
beneficial, decrease pH and prevent the growth of infectious bacteria
pathogenesis is ______
the process by which microorganisms cause disease
the decrease or loss of virulence in a pathogen is called ______
attenuation
______ are toxic glycolipids attached to the outer membrane of some pathogen cells.
endotoxins
diphtheria toxin is an example of a _____ toxin, a two- subunit protein that binds to host cell surface receptors and transfers across the cytoplasmic membrane to inhibit internal host cell functioning
AB
a disease that is present in low number and restricted areas of the world is called _____.
endemic
A(n) ______ is a disease that primarily infects animals but can be transmitted to humans.
zoonosis
the onset of a given epidemic is indicated by a sharp rise in the number of cases reported daily over a brief interval. this indicates that the mode of transmission occurs ______.
by a common source
disease _______ is measured by the total number of new and existing disease cases within a population over a period of time, a record of disease burden
prevalence
the basic reproduction number (R0) for a strain of brodetella pertussis is 16. this means that____
16 secondary cases would be expected from an infected individual
disease can be controlled through immunizations even if the percentage of the population that is immunized is less than 100% because _____.
of heard immunity
overtime, the relationship between a pathogen and a native susceptible population tends towards ______.
a balance between host and pathogen such that both are maintained
____ defines the accuracy of detection for pathogen cells ( or product) in a diagnostic test>
specificity
a disadvantage when using molecular methods in diagnostic microbiology is ______
the genome of the pathogen must be characterized
_____, periodic reports on the susceptibility of clinically isolated organism s to the antibiotics in current local use, are particularly valuable for tracking the emergence of new antibiotic-resistance strains of pathogens.
antibiograms
An acidophilic, facultative aerobe is a bacterium that would grow BEST in an _____ environment.
Oxygen-rich, acidic
The decimal reduction times of bacteria ________ with increasing temperature.
Decrease
You have discovered a new antimicrobial agent against bacteria. When you add the new chemical to a bacterial culture in exponential (log) growth phase, the live cell count remains constant and the total cell count remains constant. You classify the new antimicrobial agent as ______.
Bacteriostatic
Antiseptics (germicides), such as iodine, are distinguished from other antimicrobial agents because they ______.
Can be used on living tissues without harm
______ is the most important feature of an effective antimicrobial drug.
Selective toxicity
______ are a class of broad spectrum antibiotics (e.g. erythromycin) that inhibit microbial growth by inhibiting protein synthesis.
Macrolides
A bacterium producing beta-lactamase to degrade penicillin before it compromises the cell wall is an example of drug resistance by ______.
Inactivation
The search for new antimicrobial drugs includes ______, the introduction of viruses that attack specific pathogens into the human body.
Bacteriophage therapy
Regulatory proteins ______.
Are homodimeric
Bind to specific DNA sites
Regulate transcription