Genetics test 3
prokaryotic ribosome subunits
-large=50S -small=30S -total=70S
eukaryotic ribosome subunits
-large=60S -small=40S -total=80S
How many kinds of RNA polymerase enzymes are found in eukaryotes? Multiple choice question. 3 2 5 1
3
The RNA leader sequence is a region at the _______. Multiple choice question. 3' end of the mRNA which is untranslated 5' end of the mRNA which contains the promoter 5' end of the mRNA which is untranslated 3' end of the mRNA which contains the promoter
5' end of the mRNA which is untranslated
The lac operon genes are transcribed together in what order? Multiple choice question. 5'-lacY-lacZ-lacA-3' 5'-lacA-lacZ-lacY-3' 5'-lacA-lacY-lacZ-3' 5'-lacZ-lacA-lacY-3' 5'-lacZ-lacY-lacA-3'
5'-lacZ-lacY-lacA-3'
Regulatory sRNAs are typically ______ nucleotides long. Multiple choice question. 50-400 400-700 700-1,000 10-50
50-400
What is a spliceosome? Multiple choice question. A multicomponent structure that assists in the removal of group I and group II introns A group of ribosomes that are bound simultaneously to the same mRNA Another term for the process of alternative splicing A multicomponent structure that removes introns found in an RNA
A multicomponent structure that removes introns found in an RNA
What is a promoter? Multiple choice question. An environmental chemical that induces gene expression An element that facilitates termination of transcription A regulatory protein that accelerates mRNA turnover A specific base-pair sequence that attracts RNA polymerase, either directly or indirectly
A specific base-pair sequence that attracts RNA polymerase, either directly or indirectly
The complementarity rule used in transcription is similar to the ______ rule, except that ______ substitutes for thymine in the RNA. Multiple choice question. AG/CT; inosine AT/GC; inosine AG/CT; uracil AT/GC; uracil
AT/GC; uracil
To bring a specific amino acid into its location on a polypeptide chain, which sequence on transfer RNA must bind to messenger RNA? Multiple choice question. 5' sequence 3' sequence Anticodon Codon
Anticodon
What effect would either a loss-of-function mutation in the lacI gene or a mutation in the operator that prevents repressor binding have? Multiple choice question. Both result in constitutive expression of the lac operon. The two mutations would result in completely different phenotypes. Both result in no expression of the lac operon under any circumstance.
Both result in constitutive expression of the lac operon.
Which of the following represent common structural features of transfer RNA molecules? Multiple select question. 150-300 nucleotides in length 74-95 nucleotides in length Amino acid acceptor stem with a 3' single-stranded region Anticodon sequence Codon sequence to specify which amino acid will bind Cloverleaf shape formed by complementary base pairing
Cloverleaf shape formed by complementary base pairing Amino acid acceptor stem with a 3' single-stranded region Anticodon sequence 74-95 nucleotides in length
Which of the following is not a feature of transfer RNA molecules? Multiple choice question. Anticodon Codon Amino acid acceptor stem with a 3' single-stranded region Cloverleaf structures, stabilized by complementary base pairing
Codon
An cis-acting element is typically a ______. Multiple choice question. DNA segment that can influence only the expression of adjacent genes DNA segment that can influence the expression of different, but closely-related, operons protein that can diffuse out the cell, where it can perform its specific function protein that can diffuse through the cytoplasm and act on any DNA target in the cell
DNA segment that can influence only the expression of adjacent genes
How would the introduction of a chemical that interferes with quorum sensing help fight an infection by a pathogenic bacterium? Multiple choice question. It might reduce the levels of transcription and translation of all genes in bacterial cells. It might prevent pathogens from releasing toxins even though they have reached high densities. It might signal bacteria that they have achieved high densities even when they have not, therefore causing them to stop dividing.
It might prevent pathogens from releasing toxins even though they have reached high densities.
Which of the following proteins may function as a dimer or tetramer? Multiple choice question. β-galactosidase Lac permease Lac repressor Transacetylase
Lac repressor
What is an example of a mutation in a noncoding region that can affect the rate of translation of an mRNA? Multiple choice question. Mutation in the promoter Mutation within an intron Mutation in the 3' UTR Mutation in an enhance
Mutation in the 3' UTR
Which of the following are differences between prokaryotic and eukaryotic promoters? Multiple select question. Prokaryotic promoter sequences are closer to the transcription start site. Eukaryotic promoter sequences are simple repeats found close to the transcription start site. Prokaryotic promoters are wound into chromatin. Eukaryotic promoters are bound by histone proteins that must be released.
Prokaryotic promoter sequences are closer to the transcription start site. Eukaryotic promoters are bound by histone proteins that must be released.
Transcription is the process of synthesizing ____. Multiple choice question. DNA from an RNA template protein from an RNA template protein from a DNA template RNA from a DNA template
RNA from a DNA template
A ribozyme is a(n) ____. Multiple choice question. RNA molecule with catalytic activity ribosome that contains many enzymes enzyme that is activated upon binding RNA enzyme that digests RNA
RNA molecule with catalytic activity
prokaryotic terminators
RNA sequences that provide the signal to RNA polymerase for stopping transcription
termination of transcription - prokaryotes
RNA sequences that signal the end of transcription often form hairpin loops sometimes rho factor is involved
how does eukaryotic mRNA get is 3' poly A tail ?
Ribonuclease recognizes AAUAAA and cleaves 30 nucleotides downstream - makes new 3' end the enzyme poly A polymerase then adds 100 to 200 A's onto this new end
Which components are assembled into the subunits of a ribosome? Multiple select question. Ribosomal proteins Ribosomal RNA Transfer RNA Messenger RNA
Ribosomal proteins Ribosomal RNA
______ are allosteric RNA leaders that bind small effector molecules to control gene expression. Multiple choice question. Antiterminators Riboswitches Regulons Attenuators
Riboswitches
Why does transcription of the trp operon continue when tryptophan levels are low? Multiple choice question. The ribosome pauses in region 2, causing the 3-4 stem loop to form. The ribosome continues through the trp mRNA, preventing the 3-4 stem loop from forming. The ribosome continues through the trp mRNA, causing the 3-4 stem loop to form. The ribosome pauses in region 1, preventing the 3-4 stem loop from forming.
The ribosome pauses in region 1, preventing the 3-4 stem loop from forming.
Transcription occurs in how many stages? Multiple choice question. Two stages: initiation and termination Two stages: initiation and elongation Three stages: initiation, elongation, and termination Four stages: initiation, elongation, termination, and maturation
Three stages: initiation, elongation, and termination
Which of the following nucleotides are used during transcription? Multiple select question. UTP and ATP dUTP and dATP CTP and GTP dUTP and dTTP dCTP and dGTP
UTP and ATP CTP and GTP
When purified, the Lac repressor is ______. Multiple choice question. always a dimer always a tetramer a dimer or a tetramer a monomer or a dimer always a monomer
a dimer or a tetramer
A polyribosome is ______. Multiple choice question. a ribosome with three or more subunits many messenger RNAs bound to the same two ribosomal subunits a messenger RNA bound to a ribosome with three or more subunits many ribosomes bound to transfer RNAs a messenger RNA transcript that has many bound ribosomes in the act of translation
a messenger RNA transcript that has many bound ribosomes in the act of translation
The capping of a eukaryotic mRNA is an event that involves the addition of Multiple choice question. about 100-200 adenines to its 5' end. about 100-200 adenines to its 3' end. a methylated guanosine in reverse orientation. a methylated guanosine to its 3' end.
a methylated guanosine in reverse orientation.
The component that recognizes a stop codon during termination of translation in bacteria is ______. Multiple choice question. 16S rRNA peptidyl transferase a protein called release factor a terminating transfer RNA 23S rRNA
a protein called release factor
An effector is a small molecule that _____. Multiple choice question. binds to DNA and protects its from damage forms a complex with RNA polymerase during transcription termination forms a complex with RNA polymerase during transcription initiation binds to a protein and changes its conformation
binds to a protein and changes its conformation
The addition of a methylated "backward G" to the 5' end of a eukaryotic mRNA is a process known as ______. Multiple choice question. exon splicing polyadenylation translation capping
capping
Breakdown of sugars occurs via ______ pathways, whereas the synthesis of amino acids occurs via ______ pathways. Multiple choice question. catabolic; anabolic aerobic; anaerobic anabolic; catabolic anaerobic; aerobic
catabolic; anabolic
aminoacyl-tRNA synthetase
catalyze attachment of tRNAs to specific amino acids 2 reactions forms charged tRNA
The lacI+ allele is ______ to lacI— in ______. Multiple choice question. recessive; trans dominant; trans recessive; cis dominant; cis
dominant; trans
The genes in the trp operon encode ______. Multiple choice question. only the subunits of the trp repressor protein enzymes used to metabolize tryptophan in the environment enzymes used in tryptophan biosynthesis regulatory proteins only
enzymes used in tryptophan biosynthesis
what is a difference between transcription initiation in prokaryotes vs eukaryotes?
eukaryotes have TATA box eukaryotic genes have enhancers
A eukaryotic promoter differs from a prokaryotic promoter because _____. Multiple choice question. eukaryotic promoters are bound by histone proteins that must be released prokaryotic promoters are wound into chromatin prokaryotic promoters are larger than eukaryotic promoters eukaryotic promoters can only interact with proteins bound to sequences located very close to promoters
eukaryotic promoters are bound by histone proteins that must be released
Sequences known as exons are _____. Multiple choice question. extra regions of mRNA that are added posttranscriptionally expressed regions of DNA that are present in a mature mRNA expressed regions of DNA that are transcribed and then spliced out of an RNA extra regions of peptide that are added posttranslationally
expressed regions of DNA that are present in a mature mRNA
Why is the wobble position important?
helps prevent deleterious mutations some flexibility in genetic code
The lacA gene encodes a transacetylase, enzyme that covalently modifies _____. Multiple choice question. RNA polymerase beta-galactosidase the promoter lactose lactose permease
lactose
The wrinkled seed phenotype in Mendel's pea plants was recessive because the heterozygote produced enough functional protein to produce smooth seeds. The allele associated with wrinkled seeds is an example of a _____. Multiple choice question. loss-of-function mutation gain-of-function mutation hypermorphic mutation ectopic mutation dominant negative mutation
loss-of-function mutation
When the tryptophan level in the cell is ______, the ribosome pauses in region 1 of the trp mRNA leader, causing region 2 to bind to region 3 and transcription to continue. Multiple choice question. high low
low
what is the function of the small subunit of the ribosome? large subunit?
mRNA binding peptidyl transferase activity
A mutation in a gene that causes an amino acid change in the encoded protein is called a ______ mutation. Multiple choice question. silent sense nonsense missense
missense
Do prokaryotes have mRNA processing?
no only eukaryotes have caps and splicing
Why does mRNA require a 5' cap?
protection from nucleases
Translation is the process of synthesizing ____. Multiple choice question. protein from an RNA template DNA from an RNA template RNA from a DNA template protein from a DNA template
protein from an RNA template
An element that acts in trans is typically a ______. Multiple choice question. protein that can diffuse through the cytoplasm and act on any DNA target in the cell protein that can diffuse out the cell, where it can perform its specific function DNA segment that can influence the expression of different, but closely-related, operons DNA segment that can influence only the expression of adjacent genes
protein that can diffuse through the cytoplasm and act on any DNA target in the cell
Consider a bacterial cell with the genotype: lacI— lacZ+ lacY—/F' (lacI+ lacZ— lacY+). The expression of the genes lacZ+ and lacY+ is _____. Multiple choice question. repressed in the absence or presence of lactose repressible in the absence of lactose and inducible in its presence inducible in the absence or presence of lactose inducible in the absence of lactose and repressible in its presence
repressible in the absence of lactose and inducible in its presence
In prokaryotes, the transcription terminator is a ______. Multiple choice question. sequence in the transcript that specifies the end of transcription molecule that binds to RNA polymerase to end RNA synthesis a DNA sequence that contains several stop codons
sequence in the transcript that specifies the end of transcription
what enzyme catalyzes splicing? what is is made up of?
spliceosome five snRNAs, 50 proteins = 4 snRNPs
When lactose is depleted from the environment, ______. Multiple choice question. the repressor gene is turned off the affinity of the inducer for DNA decreases the affinity of the inducer for the repressor increases the repressor reverts to its DNA-binding shape
the repressor reverts to its DNA-binding shape
prokaryotic promoters
transcription DNA sequences that provide the signal to RNA polymerase for starting transcription
Small RNA (sRNA) molecules regulate _____. Multiple choice question. translation in cis by base-pairing with mRNAs. transcription in trans by base-pairing with DNA transcription in cis by base-pairing with DNA translation in trans by base-pairing with mRNAs
translation in trans by base-pairing with mRNAs
In prokaryotic cells, the coupling of transcription and translation refers to ______. Multiple choice question. transcription of an mRNA occurring before its translation has been completed both transcription and translation occurring in the nucleus translation of an mRNA beginning before its transcription has been completed. both transcription and translation occurring on the ribosome
translation of an mRNA beginning before its transcription has been completed.
how many cuts are needed to remove an intron?
two
Is the genetic code universal?
almost, but not quite
The order in which amino acids are added to a polypeptide chain is determined by hydrogen bonding between each codon and the ______ of the tRNA carrying the amino acid. Multiple choice question. anticodon acceptor stem variable bases 5' end
anticodon
The 5' and 3' untranslated regions of a mature eukaryotic mRNA ____. Multiple select question. are located within exons are contained within introns are added posttranscriptionally facilitate efficient transcription facilitate efficient translation
are located within exons facilitate efficient translation
The function of an aminoacyl-tRNA synthetase enzyme is to catalyze the ______. Multiple choice question. attachment of an amino acid to its appropriate tRNA synthesis of tRNA binding of a tRNA anticodon to a mRNA codon addition of a single-stranded sequence to the 3' end of the tRNA addition of amino acids to a growing polypeptide chain
attachment of an amino acid to its appropriate tRNA
how does a ribosome terminate translation?
encounters a stop codon and release factors subunits dissociate
A loss-of-function mutation in the lacI gene can have the same effect as a mutation in the _______. Multiple choice question. lacY gene operator site promoter sequence lacZ gene
operator site
what are the four general themes for gene expression?
pairing of complementary bases polarities of DNA, RNA, and polypeptides requires the input of energy mutations can change genetic information
The lac operon structural genes are transcribed as _____. Multiple choice question. three monocistronic mRNAs but only two of them have ribosome binding sites three monocistronic mRNAs each with its own ribosome binding site part of a single polycistronic mRNA with three independent ribosome binding sites part of a single polycistronic mRNA with only one ribosome binding site
part of a single polycistronic mRNA with three independent ribosome binding sites
Many bacterial mRNAs are _____ and contain multiple ribosome binding sites. Multiple choice question. polycistronic monocistronic polyribosomes zymogens
polycistronic
Scientists are currently exploring the possibility of targeting the quorum-sensing mechanism of pathogenic bacteria in the development of new antibiotics. What are advantages of this approach? Multiple select question. Signaling molecules that are used in quorum sensing are easily made in a lab. Quorum-sensing proteins do not resemble any human proteins. It might be more difficult for bacteria to develop resistance to such drugs. Such drugs would only affect pathogenic bacteria, therefore preserving the normal microbiota of the patient.w
Quorum-sensing proteins do not resemble any human proteins. It might be more difficult for bacteria to develop resistance to such drugs.
Which enzyme synthesizes RNA during transcription? Multiple choice question. RNA polymerase DNA polymerase DNA replicase RNA replicase
RNA polymerase
Which RNA polymerase transcribes genes that encode proteins in eukaryotes? Multiple choice question. RNA polymerase σ RNA polymerase III RNA polymerase II RNA polymerase I
RNA polymerase II
initiation in prokaryotes - transcription
RNA polymerase binds to promoter sequence located near the beginning of the gene coenzyme and sigma factor bind
An operon is a group of two or more genes under the transcriptional control of ______. Multiple choice question. different polymerases two or more promoters a single promoter
a single promoter
A mutation in the operator that renders it nonfunctional will cause the ______. Multiple choice question. repression of the synthesis of lactose induction of the lac operon genes constitutive expression of the lac operon complete shutdown of the lac operon
constitutive expression of the lac operon
During DNA replication, DNA polymerase forms phosphodiester bonds between ______ triphosphates, whereas during transcription, RNA polymerase forms bonds between ______ triphosphates. Multiple choice question. ribonucleotide; deoxyribonucleotide deoxyribonucleotide; ribonucleotide
deoxyribonucleotide; ribonucleotide
The lacIs allele is ______ to lacI+ in ______. Multiple choice question. dominant; trans recessive; trans dominant; cis recessive; cis
dominant; trans
The transport of ______ into a cell causes a(n) _______ in the concentration of cyclic-AMP by inhibiting adenylate cyclase. Multiple choice question. tryptophan; increase glucose; decrease allolactose; increase lactose; decrease
glucose; decrease
A lacIS mutation will affect codons for amino acids in the _____. Multiple choice question. inducer-binding domain of lacI DNA-binding domain of lacI multimerization domain of lacI
inducer-binding domain of lacI
The addition of lactose to a bacterial medium causes a 1000-fold increase in the synthesis of the two proteins Lac permease and β-galactosidase. This phenomenon is termed _______. Multiple choice question. induction transduction catabolite stimulation quorum sensing
induction
The process by which a specific molecule stimulates synthesis of a given protein is called
induction
Sequences of DNA that are not represented in the mature mRNA are called ____. Multiple choice question. poly-A tails transcripts introns exons spliceosomes
introns
The component that recognizes a stop codon during termination of translation in bacteria is ______. Multiple choice question. a terminating transfer RNA peptidyl transferase 16S rRNA 23S rRNA a protein called release factor
a protein called release factor
In bacteria, the term open promoter complex refers to the small bubble-like structure that forms ____. Multiple choice question. during the elongation phase of transcription during the termination phase of transcription during the initiation phase of transcription
during the initiation phase of transcription
Cyclic AMP is a(n) ______. Multiple choice question. effector molecule that is involved in the positive control of the lac operon effector molecule that is involved in the negative control of the lac operon source of energy used in the transport of lactose source of energy used in the breakdown of lactose
effector molecule that is involved in the positive control of the lac operon
Positive regulation and negative regulation typically refer to mechanisms that _____. Multiple choice question. enhance or inhibit DNA polymerase activity, respectively occur in eukaryotes and prokaryotes, respectively enhance or inhibit RNA polymerase activity, respectively occur in prokaryotes and eukaryotes, respectively
enhance or inhibit RNA polymerase activity, respectively
Positive regulation and negative regulation typically refer to mechanisms that _____. Multiple choice question. enhance or inhibit DNA polymerase activity, respectively occur in prokaryotes and eukaryotes, respectively occur in eukaryotes and prokaryotes, respectively enhance or inhibit RNA polymerase activity, respectively
enhance or inhibit RNA polymerase activity, respectively
The cAMP receptor protein (CRP) _______ of the lac operon. Multiple choice question. is a sequence located in the promoter functions as an activator functions as a repressor
functions as an activator
A mutation that increases the activity of a protein is a _____. Multiple choice question. hypomorphic allele gain-of-function allele haploinsufficient allele loss-of-function allele null allele
gain-of-function allele
In attenuation, transcription ______. Multiple choice question. never starts is stopped prematurely proceeds half-way through the operon continues to the transcription stop site
is stopped prematurely
what are the three levels of tRNA structure?
primary = nucleotide sequence secondary = cloverleaf shape tertiary = L shape, 3D folding
In the lac operon, some of the nucleotides of the operator are also part of the ______. Multiple choice question. activator repressor terminator promoter inducer
promoter
Consider a bacterial cell with the genotype lacI+ o+ lacZ+ lacY— that was transformed with an F' plasmid carrying lacIs o+ lacZ— lacY+. The expression of the genes lacZ+ and lacY+ in the merodiploid bacterium is ______. Multiple choice question. repressible in the absence or presence of lactose repressible in the absence of lactose and inducible in its presence inducible in the absence of lactose and repressible in its presence inducible in the absence or presence of lactose
repressible in the absence or presence of lactose
tRNA (transfer RNA)
short, single-stranded RNAs of 74-95 nt coupled to an amino acid has an anticodon directed by a ribosome
elongation in prokaryotes transcription
sigma factor dissociates RNA poly moves in 3->5 direction transcription is constant and many RNA polymerase can transcribe simultaneously
what three short sequences determine where splicing occurs?
splicing donor - GU spicing acceptor - AG branch site
Constitutive mutants ______. Multiple choice question. synthesize certain proteins all the time lack the ability to synthesize proteins synthesize certain proteins occasionally synthesize only one category of proteins
synthesize certain proteins all the time
A codon specifies the correct amino acid by using ______ as an adapter molecule. Multiple choice question. tRNA snRNA ribosomal RNA mRNA
tRNA
The conversion of a riboswitch from one conformation to another is due to _____. Multiple choice question. an inducer the presence of CAP the covalent modification of the final product the binding of a small molecule
the binding of a small molecule
What is gene expression?
the flow of genetic information from DNA to RNA to protein
RNA splicing refers to _____. Multiple choice question. the removal of introns from DNA the addition of untranslated regions to RNA the removal of introns from RNA the removal of exons from RNA the joining together of multiple transcripts to make a polypeptide
the removal of introns from RNA
