PMG Final Flashcards
A mutation always causes a mutant phenotype. T or F
Fasle
A messenger is 336 nucleotides long, including the initiator and termination codons. The number of amino acids in the protein translated from this mRNA is
111
A spontaneous mutation usually originates as an error in
DNA replication
A ____ mutation affects the phenotype only under certain conditions.
conditional
Changing the codon AGC to AGA represents a ____ mutation.
nonsense
A point mutation that changes a codon specifying an amino acid into a stop codon is called a
nonsense
The enzyme that creates a short RNA oligonucleotide at initiation sites where replication is to be carried out is
called
Primase
Gram-negative: have double cell membrane. T or F
True
Nucleotides in each strand are linked by 5’-3’ phosphodiester bonds. T or F
true
DNA synthesis on the lagging strand is continuous. T or F
False
n the lagging during the DNA synthesis the Okasaki fragments are synthesized. T or F
True
Bacteria have one circular chromosome, main genome (which carries housekeeping genes). To or F
True
The replication of the bacterial chromosome is unidirectional
False
What relaxes strands
topoisomerase or girase
What opens strand and acts as guide for primase on both strands
Helicase
What keeps the strands apart during the replication process
Single binding proteins
What synthesizes primer sequences that are used by DNA polymerase III
Primase
What extends strands only in 5’ 3’ direction, thus one strand is continuous and one is in short
fragments (Okazaki fragments)
DNA Polymerase 3
Replication continues until the replication fork enters a region of the chromosome called
Ter
Partitioning of the chromosome: is the distribution of one daughter chromosome to each of the two daughter cells. T or F
True
RNA which is able to pick up a specific amino acid, transfers it to ribosomes
tRNA
is synthesized complementary to a gene and subsequently translated into a polypeptide or protein at ribosomes
mRNA
Below is the schematic representation of _______. Indicate the function its sub-units (show it below)
RNA polymerase
Promoter is a nucleotide sequence up stream of the gene to which RNA polymerase binds at the initiation of transcription. T or F?
True
___ is where an aminoacyl-tRNA first attaches
site A or acceptor or aminoacyl site
The peptide bond is formed by a ribozyme, called
peptidyl transferase
___ is where the growing amino acid chain is temporarily being held by a tRNA as the next codon in the mRNA is being read.
site P or peptide site
____ Break the covalent bond that holds the finished protein to the terminal tRNA.
Release factors
Sec YEG : proteins that assist the non-covalent folding/unfolding. T or F
True
Which mRNA codes for the following polypeptide?
met arg ser leu glu
a) 3’-AUG CGU AGC UUG GAG UGA-5’
b) 3’-AGU GAG GUU CGA UGC GUA-5’
c) 5’-AUG CGU AGC UUG GAG UGG-3’
d) 1’-AUGCGUAGCUUGGAGUGA-3’
e) 3’-AUGCGUAGCUUGGAGUGA-1’
c) 5’-AUG CGU AGC UUG GAG UGG-3’
What is the consequence of a nonsense mutation?
Introduces a stop codon
A transition is a point mutation in which a purine is replaced by the other purine (A for G or G for A) or a pyrimidine by the other pyrimidine (C for T or T for C). A transversion is a point mutation in which a pyrimidine is replaced by a purine or vice versa. Some point mutagens (mutagenic chemicals that cause point mutations) mainly cause transitions or mainly transversions or mainly frameshift mutations.
Gene A contains a frameshift mutation. To revert that mutation (change it back to normal or wild type) you would use a
Mutagen causing frameshifts
A transition is a point mutation in which a purine is replaced by the other purine (A for G or G for A) or a pyrimidine by the other pyrimidine (C for T or T for C). A transversion is a point mutation in which a pyrimidine is replaced by a purine or vice versa. Some point mutagens (mutagenic chemicals that cause point mutations) mainly cause transitions or mainly transversions or mainly frameshift mutations.
To revert a transition mutation you would use a
mutagen causing transitions
A transition is a point mutation in which a purine is replaced by the other purine (A for G or G for A) or a pyrimidine by the other pyrimidine (C for T or T for C). A transversion is a point mutation in which a pyrimidine is replaced by a purine or vice versa. Some point mutagens (mutagenic chemicals that cause point mutations) mainly cause transitions or mainly transversions or mainly frameshift mutations.
To revert a transversion mutation you would use a
mutagen causing transversions
The lac operon is expressed when
glucose is low and lactose is absent.
When in a complex with ________, the CAP protein binds to the CAP site and ________ the expression of the lac
operon
cAMP ; switches on
In the absence of lactose, the lac repressor is
active and can bind to the operator.
The inducer of the lac operon is an isomer of lactose. T or F
TRUE
When RNA polymerase is bound to the lac promoter sequence, transcription of the lac operon is on. T or F
True
The trp operon consists of ________ structural genes.
five
In the absence of tryptophan, the trp repressor is
inactive and cannot bind to the operator.
In the presence of tryptophan, tryptophan binds to the
trp repressor.
In the presence of tryptophan, transcription of the trp operon is on. T or F
False
An operon is a group of genes that is under the control of a single operator site. T or F
False
Cells of an E. coli strain that are trp - lac Z- met+ bio+ were mixed with cells of an E. coli strain that are trp + lac Z + met- bio- and cultured for several hours. Then cells were removed, washed, and transferred to minimal media containing
lactose as the only sugar source. A few cells were able to grow on minimal media with lactose, and formed colonies. How
did these few cells become trp+ lac+ Z met+
bio+ ?
Conjugation
How many lac Z genes were present in the cells described in the previous problem (11) that were able to grow on minimal media?
Cells of an E. coli strain that are trp - lac Z- met+ bio+ were mixed with cells of an E. coli strain that are trp + lac Z + met- bio- and cultured for several hours. Then cells were removed, washed, and transferred to minimal media containing
lactose as the only sugar source. A few cells were able to grow on minimal media with lactose, and formed colonies. How
did these few cells become trp+ lac+ Z met+
bio+ ?
Two, the lac Z- allele on the bacterial chromosome and the lac Z+ allele on the F’ episome.
How would you describe the regulation of lactose metabolism in the cells described in problem 11 that were able to grow on minimal media with lactose as a nutrient?
Cells of an E. coli strain that are trp - lac Z- met+ bio+ were mixed with cells of an E. coli strain that are trp + lac Z + met- bio- and cultured for several hours. Then cells were removed, washed, and transferred to minimal media containing
lactose as the only sugar source. A few cells were able to grow on minimal media with lactose, and formed colonies. How
did these few cells become trp+ lac+ Z met+
bio+ ?
normal regulation of lactose metabolism.
An E. coli strain that is lac Z is conjugated with E. coli cells carrying an F’ plasmid with the plac Oc lac Z DNA sequence on the episome. The Oc is a mutation of the lactose operator that is no longer able to bind the lac I gene product which codes for the lac repressor. How would the expression of the lac Z be regulated in the resulting cells that are diploid for the lactose regulatory region and the lac Z gene?
constitutive expression of lac Z+.
An E. coli strain that is lac Z is conjugated with E. coli cells carrying an F’ plasmid with the plac Oc lac Z DNA sequence on the episome. The Oc is a mutation of the lactose operator that is no longer able to bind the lac I gene product which codes for the lac repressor. How would the expression of the lac Z be regulated in the resulting cells that are diploid for the lactose regulatory region and the lac Z gene?
Predict the phenotype of a lacI mutant.
The lac genes would be expressed continuously.
An E. coli strain that is lac Z is conjugated with E. coli cells carrying an F’ plasmid with the plac Oc lac Z DNA sequence on the episome. The Oc is a mutation of the lactose operator that is no longer able to bind the lac I gene product which codes for the lac repressor. How would the expression of the lac Z be regulated in the resulting cells that are diploid for the lactose regulatory region and the lac Z gene?
If a second wild type or normal copy of the lacI gene (just lacI and not lacZ, lacY, or lacA) is introduced into the lacI mutant cell, what would be the phenotype of this partial diploid (also referred to as a merodiploid)?
The lac genes would be expressed efficiently only in the presence of lactose.
An E. coli strain that is lac Z is conjugated with E. coli cells carrying an F’ plasmid with the plac Oc lac Z DNA sequence on the episome. The Oc is a mutation of the lactose operator that is no longer able to bind the lac I gene product which codes for the lac repressor. How would the expression of the lac Z be regulated in the resulting cells that are diploid for the lactose regulatory region and the lac Z gene?
Predict the phenotype of a lacI S or “super-repressor” mutant. A lacI S mutant synthesizes a repressor that cannot bind
to the inducer.
The lac genes would never be expressed efficiently.
An E. coli strain that is lac Z is conjugated with E. coli cells carrying an F’ plasmid with the plac Oc lac Z DNA sequence on the episome. The Oc is a mutation of the lactose operator that is no longer able to bind the lac I gene product which codes for the lac repressor. How would the expression of the lac Z be regulated in the resulting cells that are diploid for the lactose regulatory region and the lac Z gene?
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.
The lac genes would never be expressed efficiently.
An E. coli strain that is lac Z is conjugated with E. coli cells carrying an F’ plasmid with the plac Oc lac Z DNA sequence on the episome. The Oc is a mutation of the lactose operator that is no longer able to bind the lac I gene product which codes for the lac repressor. How would the expression of the lac Z be regulated in the resulting cells that are diploid for the lactose regulatory region and the lac Z gene?
Predict the phenotype of an operator mutant (Oc) which would prevent the binding of the repressor.
The lac genes would be expressed continuously
An E. coli strain that is lac Z is conjugated with E. coli cells carrying an F’ plasmid with the plac Oc lac Z DNA sequence on the episome. The Oc is a mutation of the lactose operator that is no longer able to bind the lac I gene product which codes for the lac repressor. How would the expression of the lac Z be regulated in the resulting cells that are diploid for the lactose regulatory region and the lac Z gene?
Predict the phenotype of a promoter mutant (lacP) which has a mutation in the promoter for the lac operon.
The lac genes would never be expressed efficiently.
An E. coli strain that is lac Z is conjugated with E. coli cells carrying an F’ plasmid with the plac Oc lac Z DNA sequence on the episome. The Oc is a mutation of the lactose operator that is no longer able to bind the lac I gene product which codes for the lac repressor. How would the expression of the lac Z be regulated in the resulting cells that are diploid for the lactose regulatory region and the lac Z gene?
Predict the phenotype of a lacZ mutant, which has a mutation in the gene for β-galactosidase.
The production of β-galactosidase would be affected, but other protein products would be unaffected.
An E. coli strain that is lac Z is conjugated with E. coli cells carrying an F’ plasmid with the plac Oc lac Z DNA sequence on the episome. The Oc is a mutation of the lactose operator that is no longer able to bind the lac I gene product which codes for the lac repressor. How would the expression of the lac Z be regulated in the resulting cells that are diploid for the lactose regulatory region and the lac Z gene?
Predict the phenotype of a lacY mutant, which has a mutation in the gene for lactose permease.
The lac genes would be expressed efficiently until the lactose supply in the cell is exhausted.
DNA transformation involves the transfer of DNA via
naked DNA in solution
When DNA from an ampicillin resistant organism is brought into an ampicillin sensitive organism by transformation
and the product is grown on agar containing ampicillin
only the transformed cells will grow
In transformation, both strands of donor DNA enter the recipient cell. T or F
False
Donor DNA is combined with recipient DNA by homologous recombination. T or F
True
A bacterial cell that is able to take up naked DNA is said to be
competent
Which of these describes a similarity between the lac and ara operons?
A) Expression of structural genes does not occur at high glucose concentrations.
B) lacI and araI both encode trans acting factors.
C) Binding of a regulatory protein is prevented in the presence of an inducer.
D) All of these are similarities.
E) None of these are similarities.
A) Expression of structural genes does not occur at high glucose concentrations.
Attenuation of the trp operon:
A) Occurs when transcription is complete before translation begins.
B) Is mediated by the trp repressor protein.
C) Occurs in the presence of high levels of tryptophan.
D) All of the above.
E) None of the above.
C) Occurs in the presence of high levels of tryptophan
A prophage is
phage DNA integrated into host cell genome
One of the largest global regulatory systems in bacteria are
Catabolite-Sensitive Operons
CAP contains an “activating region” that has been proposed to participate in direct protein-protein interactions with RNA polymerase and/or other basal transcription factors.
a) in the Lac operon
b) in the Trp operon
c) in all Catabolite-Sensitive Operons
d) in Ara operon
e) in Lac and Ara operons
c) in all Catabolite-Sensitive Operons
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. T or F
False
_____ protein may be a “cellular thermometer” that senses the change in temperature and induces the transcription of
heat shock genes
DnaK
Sigma-32 binds to the RBS of its own mRNA and blocks access of the ribosome. T or F
True
Immediately after a temperature increase
a)most of the DnaK will have to help renature unfolded proteins, thus making DnaK unavailable for binding
sigma-32. So free sigma-32 is more stable (less susceptible to protease digestion) and more active.
b) most of the DnaK will have to help renature unfolded proteins, thus making DnaK available for binding sigma-32. So free sigma-32 is less stable (less susceptible to protease digestion) and more active.
c) most of the DnaK will be available for binding sigma-32; therefore bound sigma-32 is more stable (less susceptible to protease digestion) and more active.
a)most of the DnaK will have to help renature unfolded proteins, thus making DnaK unavailable for binding
sigma-32. So free sigma-32 is more stable (less susceptible to protease digestion) and more active.
Transcriptional Regulation during the development of a typical large DNA phage the ________________ products are responsible for regulation the transcription (turn on or off the transcription of other genes)
Regulatory
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
most of the DnaK will have to help renature unfolded proteins, thus making DnaK unavailable for binding
sigma-32. So free sigma-32 is more stable (less susceptible to protease digestion) and more active.
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
The use or alteration of cells or biochemicals to provide a useful product describes
Biotechnology
Which of the technologies listed below is a valuable method for mass-producing drugs and other useful proteins?
a) recombinant DNA technology
b) transgenic technology
c) biotechnology
d) gene targeting
a) recombinant DNA technology
Manufacturing recombinant DNA molecules involves cutting a gene from its normal location, inserting it into a circular piece of DNA from a bacterial cell, and then transferring the circle of DNA to cells of another species. Which of the tools below is used to cut the gene from its normal location?
a) restriction enzyme
b) plasmid
c) bacteriophage d) vector
a) restriction enzyme
Manufacturing recombinant DNA molecules involves cutting a gene from its normal location, inserting it into a circular piece of DNA from a bacterial cell, and then transferring the circle of DNA to cells of another species. Which of the below describe the circular piece of DNA from a bacterial cell?
a) restriction enzyme
b) plasmid
c) bacteriophage
d) vector
B) plasmid
Which gene transfer technique involves a tiny needle which is used to inject DNA into a cell lacking that DNA sequence?
microinjection
The process of ____ involves the introduction of a gene into a cell where it exchanges places with its counterpart in the host cell.
Gene targeting
Genetic engineering manipulates gene products at the level of the
DNA
A cDNA version of a gene includes
codons for a mature mRNA.
____ are used to select genes of interest from a genomic library.
DNA probes
Sequence similarity searching algorithms like BLAST are based on the premise that if two sequences are similar then they are likely to be homologous. T or F
true
A motif is a distinctive pattern of amino acids, conserved across many proteins, which gives a particular function to the protein. T or F
True
Expression libraries are made with
Complementary DNA (cDNA)
To understand the functions of genes we use reverse genetics and some of its tools are a) RNAi
b) Knockout study c) Microarray
d) a and b
e) a, b and c
e) a, b and c
Which of the following tools of recombinant DNA technology is INCORRECTLY paired with its use?
a) Restriction endonuclease - production of DNA fragments for gene cloning
b) DNA ligase - enzyme that cuts DNA, creating sticky ends
c) DNA polymerase - copies DNA sequences in the polymerase chain reaction
d) Reverse transcriptase - production of cDNA from mRNA
B) DNA ligase - enzyme that cuts DNA, creating sticky ends
The “Southern” technique involves:
The detection of DNA fragments on membranes by a radioactive DNA probe
“Gene library” is a term used to describe:
b) Bacteria with plasmids containing DNA fragments representing the majority of the genetic information
