Final Exam problems Flashcards
Predict how a lacI S mutant would be affected by the construction of a merodiploid that has a second normal copy of the lacI gene.
a) the lac genes would be expressed efficiently only in the absence of lactose
b) the lac genes would be expressed efficiently only in the presence of lactose
c) the lac genes would be expressed continuously
d) the lac genes would never be expressed efficiently
d) the lac genes would never be expressed efficiently
_______ opens strand and acts as guide for primase on both strands
Helicase
In specialized transduction
a) requires a phage that uses the lysogenic cycle for reproduction
b) only certain bacterial genes can be transferred and these genes, as you will see, must exist on either side of the prophage
c) a phage that uses the lytic cycle for reproduction
d) whatever piece of bacterial DNA happens to get packaged within the phage is the genetic material that will be transferred between cells.
e) A and B
e) A and B
A point mutation that changes a codon specifying an amino acid into a stop codon is called a a) missense mutation b) nonsense mutation c) frameshift mutation d) deletion mutation
b) nonsense mutation
(True/False) Some Hsp are chaperones that direct the folding of newly-translated proteins. In heat shock, they bind to denatured proteins and either help to refold them into their inactive conformations or, if the protein is extensively denatured, chaperones target these proteins for destruction.
False
The 70S ribosome moves a distance of one codon down the mRNA through a process called
a) site A or acceptor or aminoacyle site
b) translocation
c) peptidyl transferase
d) site P or peptide site
e) release factors
b) translocation
What is the consequence of a nonsense mutation?
a) Prevents DNA replication
b) Codes for the wrong amino acid
c) Deletes promoter region
d) Introduces a stop codon
d) Introduces a stop codon
Suppose there is not preference codon
The trp operon consists of ______ structural genes.
a) one
b) two
c) three
d) four
e) five
e) five
In the absence of tryptophan, the trp repressor is
a) active and can bind to the operator
b) active and cannot bind to the operator
c) inactive and cannot bind to the promoter
d) inactive and can bind to the operator
e) inactive and cannot bind to the operator
e) inactive and cannot bind to the operator
a) transformation
b) transduction
c) sexduction
d) conjugation
e) transposition
d) conjugation
(True/False) Sec YEG: proteins that assist the non-covalent folding/unfolding
True
(True/False) Gram-negative: have double cell membrane
True
One of the largest global regulatory systems in bacteria are
a) Catabolite-Sensitive operons
b) oxygen stress operons
c) pH shock system
a) catabolite-sensitive operons
Predict the phenotype of a promoter mutant (lacP) which has a mutation in the promoter for the lac operon.
a) the lac genes would be expressed efficiently only in the absence of lactose
b) the lac genes would be expressed efficiently only in the presence of lactose
c) the lac genes would be expressed continuously
d) the lac genes would never be expressed efficiently
d) the lac genes would never be expressed efficiently
Is where the growing amino acid chain is temporarily being held by a tRNA as the next codon in the mRNA is being read.
a) site A or acceptor or aminoacyle site
b) translocation
c) peptidyl transferase
d) site P or peptide site
e) release factors
d) site P or peptide site
A nucleic acid was analyzed and found to contain 32 perecnt A, 18 percent G, 17 percent C, and 33 percent T. The nucleic acid must be:
a) single-stranded RNA
b) single-stranded DNA
c) double-stranded RNA
d) double-stranded DNA
b) single-stranded DNA
DNA transformation involves the transfer of DNA via
a) pili
b) naked DNA in solution
c) a restriction endonuclease
d) a bacteriophage
b) naked DNA in solution
Go over on paper
A ______ mutation affects the phenotype only under certain conditions. a) spontaneous b) somatic c) site-directed d) conditional
d) conditional
(True/False) In transformation, both strands of donor DNA enter the recipient cell.
False
The lac operon is expressed when
a) glucose is high and lactose is present
b) glucose is high and lactose is absent
c) glucose is low and lactose is present
d) glucose is low and lactose is absent
e) glucose is low, regardless of the presence or absence of lactose
d) glucose is low and lactose is absent
(True/False) An operon is a group of genes that is under the control of a single operator site
False
_______ keep strand apart during the replication process
single-binding proteins
______ protein may be a “cellular thermometer” that senses the change in temperature and induces the transcription of heat shock genes
a) sigma 32
b) sigma E
c) DnaK
d) DnaI
c) DnaK
Below is the schematic representation of _________.
RNA polymerase
Replication continues until the replication fork enters a region of the chromosome called _______.
Ter
Indicate the function of sub-units
(True/False) Donor DNA is combined with recipient DNA by homologous recombination
True
Predict the phenotype of an operator mutant (Oc) which would prevent the binding of the repressor.
a) the lac genes would be expressed efficiently only in the absence of lactose
b) the lac genes would be expressed efficiently only in the presence of lactose
c) the lac genes would be expressed continuously
d) the lac genes would never be expressed efficiently
c) the lac genes would be expressed continuously
(True/False) Partitioning of the chromosome: is the distribution of one daughter chromosome to each of the two daughter cells.
True
Suppose the preference codon for S is 60% TCT, 30% TCC, and 2.5% in each of the other codons.