Which types of mutation are generated by site-specific recombination systems?
Insertions
Inversions
Translocations
Excisions
Transitions - CORRECT
... [Show More] ANSWER Insertions
Inversions
Translocations
Excisions
What is not true of RecBCD-mediated recombination?
-The RecBCD system is dispensable in bacteria
-RecB has both 3' to 5' and 5' to 3' exonuclease activity
-RecBCD binds to the ends of double stranded DNA breaks
-Recognition of a Chi sequence by RecC leads to slowing down of the 3' to 5' exonuclease
activity of RecB
-RecA promotes the binding of RecB to single stranded DNA - CORRECT ANSWER -RecA
promotes the binding of RecB to single stranded DNA
"In strain engineering, an antibiotic resistance marker used for marker exchange mutegenesis is
flanked with FRT sequences to:" - CORRECT ANSWER Facilitate excision of the antibiotic
resistance marker from the bacterial genome in the presence of flippase
Of the proteins involved in the resolution of the Holliday junction which one has endonuclease
activity? - CORRECT ANSWER RuvC
What is a role for homologous recombination in nature? - CORRECT ANSWER Restarting
stalled replication forks
Which protein or proteins are involved in the homologous recombination process? - CORRECT
ANSWER RecA
RecBCD
RuvABC
RecFOR
What is true of bacterial exotoxins? - CORRECT ANSWER -Most exotoxins are heat sensitive
-Exotoxins can be inactivated using formalin to make vaccines
-Exotoxins targets host cells that have specific receptors on the cell surface
-Different exotoxins have different targets in human cells
-Many exotoxins have enzymatic activities
They are NOT produced only by Gram-negative bacteria
"What is a pathogenic bacterial genus for which a bacteriophage is being developed for
treatment, but is not commonly implicated in bacterial food poisoning?" - CORRECT ANSWER
Acinetobacter
What is not a role of the proteins involved in lambda red-mediated recombineering ?
-Beta binds to exposed single stranded DNA
-Gam degrades one strand of the incoming DNA to produce single stranded DNA
-Exo binds to the ends of double stranded DNA
-Beta nucleoprotein synapses with homologous sequences in the cloning vector
-Gam inhibits the exonuclease activity of E. coli's RecBCD - CORRECT ANSWER -Gam
degrades one strand of the incoming DNA to produce single stranded DNA
What is true of the pET protein expression system and how it works?
-"In the presence of IPTG, there will be increased expression of the T7 gp1 gene. "
-"At low cell densities, expression of a toxic recombinant protein can be tightly repressed by
adding glucose to the growth media"
-"In the presence of IPTG, T7 RNA polymerase can bind to and drive expression of the T7 gp10
promoter."
-"In the presence of IPTG, LacI will dissociate from the lacO sequences"
-T7 DNA polymerase is required for replication of the pET plasmid - CORRECT ANSWER -"In
the presence of IPTG, there will be increased expression of the T7 gp1 gene. "
-"At low cell densities, expression of a toxic recombinant protein can be tightly repressed by
adding glucose to the growth media"
-"In the presence of IPTG, T7 RNA polymerase can bind to and drive expression of the T7 gp10
promoter."
-"In the presence of IPTG, LacI will dissociate from the lacO sequences"
"In the pET system for recombinant protein expression, in the absence of IPTG:" - CORRECT
ANSWER The gene of interest cloned in the pET plasmid is not expressed
Which are bacterial defenses against bacteriophages?
-The bacteria incorporates novel base derivatives in its DNA
-A bacterial gene that codes for the bacteriophage receptor mutated and is no longer expressed
-Bacterial CRISPR RNA tags phage DNA for degradation by CAS endonuclease
-"An infected bacterium immediately dies upon bacteriophage infection and traps the phage in
the process,."
-All the other choices are bacterial defenses against phage infection
A host bacterium evolves a new restriction enzyme that can degrade phage DNA - CORRECT
ANSWER -A bacterial gene that codes for the bacteriophage receptor mutated and is no longer
expressed
-Bacterial CRISPR RNA tags phage DNA for degradation by CAS endonuclease
-"An infected bacterium immediately dies upon bacteriophage infection and traps the phage in
the process,."
A host bacterium evolves a new restriction enzyme that can degrade phage DNA
What is the enzymatic function of gene product 1 in T7? - CORRECT ANSWER Synthesis of
phage specific mRNA
Which event in bacteriophage lambda will favor lysogeny over lysis? - CORRECT ANSWER
absence of extensive DNA damage
Which events in bacteriophage lambda will favor lysis over lysogeny?
-Cro repression of cI expression
-Increased expression of the croI repressor
-Autocleavage of CI dimers upon contact with RecA-ssDNA nucleoprotein
-Absence of extensive damage in the bacterial chromosome
-"CI activation of genes controlled by phage promoters, pL and pR" - CORRECT ANSWER -
Cro repression of cI expression
-Increased expression of the croI repressor
-Autocleavage of CI dimers upon contact with RecA-ssDNA nucleoprotein
-"CI activation of genes controlled by phage promoters, pL and pR"
What applies more to specialized than to generalized transduction? - CORRECT ANSWER
Mostly bacterial sequences close to attB site are transferred during transduction
In which pathogenic bacteria will you find an A toxin that removes adenine from 28sRNA to
block translation? - CORRECT ANSWER E. coli O157:H7
What applies to bacteriophages? - CORRECT ANSWER -Most phages have narrow host range
-Bacteriophages are viruses that infect bacteria
-All phages use the host's replication machinery to some extent
-Bacteriophage recognize molecules on bacterial surface to infect
-"Bacteriophage genomes can be RNA, but mostly DNA"
Which pathogenic bacteria produces an A toxin that causes toxic shock syndrome characterized
by a runaway immune reaction? - CORRECT ANSWER Staphylococcus aureus
What is true about chemical transformation? - CORRECT ANSWER -The DNA-competent cell
mixture should be chilled on ice prior to heat shock
-Cells are washed with cold CaCl which coats the DNA with positive charges (shield negatively
charged DNA in environment from negative charge of bacterial cell wall)
-Heat shock causes pores to open to take up this DNA
What is not a naturally occurring plasmid? - CORRECT ANSWER pJET in a bacterium which
breaks down jet fuel
Which are naturally occurring plasmids? - CORRECT ANSWER -"Symbiosis plasmid, pSym, in
legume bacteria"
-ColE1 which carries a gene coding for an antimicrobial peptide
-TOL plasmid carrying genes involved in toluene degradation
-"The tumor-inducing, Ti plasmid, of Agrobacterium tumefaciens"
-RK2 which carries resistance to kanamycin
What is an unlikely use of transformation? - CORRECT ANSWER Complementation using
phage genomic libraries
Which are likely uses of transformation?
-Introducing translational or transcriptional reporters
-Deliver marker exchange construct for reverse genetics and strain engineering
-Complementation using phage genomic libraries
-Genomic library construction
-Complementation and mapping of genes or mutations - CORRECT ANSWER -Introducing
translational or transcriptional reporters
-Deliver marker exchange construct for reverse genetics and strain engineering
-Genomic library construction
-Complementation and mapping of genes or mutations [Show Less]