Exam3 pretest(merge-update 2)

Ribosomes consist of __________ separate subunits that come together as part of the initiation process and dissociate immediately after termination. A. two B. three C. four D. five

A. two

How many different termination codons are used in translation? A. one B. two C. three D. four

C. three

A consensus sequence in the untranslated leader sequence of a prokaryotic mRNA which serves as a ribosome binding site is called the __________ sequence.

Shine-Delgarno

One way to regulate gene expression is through the production of different sigma factors. These cause RNA polymerase to bind to different sets of promoters, thereby altering the pattern of gene expression.

True

Messenger RNA molecules that direct the synthesis of more than one polypeptide are said to be __________.

polycistronic

In eukaryotes a so-called cap consisting of __________ is attached to the 5' end of the molecule during posttranscriptional modification of hnRNA to produce functional mRNA.

7-methyl guanosine

What is the minimum number of aminoacyl-tRNA synthetase enzymes needed to attach amino acids to all the various tRNA molecules? A. 20. B. 61. C. 64. D. as many as there are different tRNAs.

A. 20

Prokaryotic DNA replication occurs at a rate of A. 750-1,000 base pairs per second. B. 750-1,000 base pairs per minute. C. 50-100 base pairs per second. D. 50-100 base pairs per minute.

A. 750-1000 base pairs per second

Which of the following is not a termination codon? A. AUG B. UAA C. UAG D. UGA

A. AUG

Which of the following is the initiator codon? A. AUG B. UAA C. UAG D. UGA

A. AUG

In eukaryotes a series of __________ residues are added to the 3' end of an RNA molecule as part of the posttranscriptional processing used to produce functional mRNA. A. Adenine B. Guanine C. Cytosine D. Uracil

A. Adenine

Which of the following individuals or groups of individuals demonstrated that the transforming principle was DNA? A. Avery, MacLeod, and McCarty B. Griffith C. Hershey and Chase D. Watson and Crick

A. Avery, MacLeod, and McCarty

The expressed regions of split genes are called A. Exons B. Endons C. Introns D. Codons

A. Exons

Which of the following is not a pyrimidine? A. adenine B. cytosine C. thymine D. uracil

A. adenine

The chromosomes of most bacteria are comprised of A. double-stranded circular molecules. B. double-stranded linear molecules. C. single-stranded circular molecules. D. single-stranded linear molecules.

A. double-stranded circular molecules

__________ alter repressor proteins thereby increasing the rate of transcription initiation. A. Inducers B. Corepressors C. Effectors D. Modulators

A. inducers

The transcribed, but not translated, sequence that is immediately upstream of the region that encodes the functional product is called the __________ region. A. leader B. promoter C. coding D. trailer

A. leader

A complex consisting of a single mRNA molecule with several ribosomes is called a A. polysome. B. multisome. C. maxisome. D. none of the choices

A. polysome

In __________ ribosomes can attach to the mRNA and begin translation even though transcription has not been completed. A. prokaryotes B. eukaryotes C. fungi D. protozoa and some plants

A. prokaryotes

The coding sequence in the DNA of __________ is normally continuous; that is, it is not interrupted by noncoding sequences. A. prokaryotes B. plants C. mammals D. most insects

A. prokaryotes

If Escherichia coli is cultured in broth containing both glucose and lactose, it A. uses glucose preferentially until the supply is exhausted, then uses lactose. B. uses lactose preferentially until the supply is exhausted, then uses glucose. C. uses glucose and lactose simultaneously. D. uses only the glucose (it cannot use lactose as a source of carbon).

A. uses glucose preferentially until the supply is exhausted, then uses lactose

The principle of transformation was first demonstrated by which of the following individuals or groups of individuals? A. Avery, MacLeod, and McCarty B. Griffith C. Hershey and Chase D. Watson and Crick

B. Griffith

RNA polymerase II of eukaryotes is responsible for transcribing A. RRNA B. MRNA C. TRNA D. All of the above

B. MRNA

________ molecules deliver amino acids to ribosomes during translation. A. Messenger RNA (mRNA) B. Transfer RNA (tRNA) C. Ribosomal RNA (rRNA) D. Heterogeneous nuclear RNA (hnRNA)

B. Transfer RNA

Which of the following is not considered the final product of the expression of a gene? A. A polypeptide chain. B. An mRNA molecule. C. A tRNA molecule. D. An rRNA molecule.

B. an mRNA molecule

The portion of the tRNA molecule that binds to the codon on the mRNA is called the A. c-codon. B. anticodon. C. complementary codon. D. paracodon.

B. anticodon

__________ activate repressor proteins thereby decreasing the synthesis of certain enzymes. A. Inducers B. Corepressors C. Effectors D. Modulators

B. corepressors

The genetic code is said to be __________ because more than one codon will specify a particular amino acid. A. ambiguous B. degenerate C. multiplicative D. repetitious

B. degenerate

The Y-shaped part of the DNA molecule where the actual replication process occurs is called the replication __________. A. tongue B. fork C. junction D. splice

B. fork

A section of DNA that codes for a protein or other functional product is called a(n) A. codon. B. gene. C. replicon. D. anticodon.

B. gene

The genetic information in DNA is divided into units called A. proteins. B. genes. C. genotype. D. phenotype.

B. genes

In two component regulatory systems, the response regulator typically receives a ____________ from the sensor kinase when it has been activated. A. pyruvate group B. phosphoryl group C. acetyl group D. methyl group

B. phosphoryl group

The region at which the RNA polymerase binds is the __________ region. A. leader B. promoter C. coding D. trailer

B. promoter

While standard two-component regulatory systems typically act to control gene transcription, phosphorelay systems can act either to control gene transcription or to control A. translation. B. protein activity. C. DNA replication. D. all of the choices.

B. protein activity

When RNA polymerase catalyzes the addition of a nucleotide to a growing mRNA chain, a byproduct of this reaction is A. phosphate. B. pyrophosphate. C. orthophosphate. D. water.

B. pyrophosphate

The strand of DNA for a particular gene that is copied by the RNA polymerase to form mRNA is called the __________ strand. A. leading B. template C. transcription D. copy

B. template

The sensor kinase for the OmpF: OmpC two-component regulatory system is A. the OmpK protein. B. the EnvZ protein. C. the MicF RNA. D. none of the choices.

B. the EnvZ protein

In order to add a single amino acid to a growing polypeptide chain, a grand total of __________ molecules or ATP or GTP are utilized. A. two B. three C. four D. six

B. three

The genetic code is translated in groups of __________ bases. A. two B. three C. four D. five

B. three

The process by which the base sequence of all or a portion of a DNA molecule is used to direct the synthesis of an RNA molecule is called A. replication. B. transcription. C. reverse transcription. D. translation.

B. transcription

The __________ reaction sequentially links adjacent amino acids into the growing polypeptide chain. A. dipeptidation B. transpeptidation C. peptidation D. propeptidation

B. transpeptidation

When arabinose is present in the environment, the AraC protein acts as a(n) ______________ for the E. coli ara operon. A. Anti-repressor B. Co-repressor C. Activator D. Repressor

C. Activator

RNA polymerase III of eukaryotes is responsible for transcribing A. RRNA B. MRNA C. TRNA D. All of the above

C. TRNA

Which of the following is not a complementary base pair usually found in DNA molecules? A. adenine-thymine B. guanine-cytosine C. adenine-uracil D. all of the choices

C. adenine-uracil

Regulation of gene expression serves to do all of the following except A. conserve energy and raw materials. B. maintain balance between the amounts of various cell proteins. C. adjust the activity of existing proteins in the cell. D. adapt to long-term environmental change.

C. adjust the activity of existing proteins in the cell

The transcribed and translated region of a gene is the __________ region. A. leader B. promoter C. coding D. trailer

C. coding

Key sequences exist within promoters, which vary somewhat among various promoters but are sufficiently constant that they can be represented by a sequence of bases most often found at each position. These representations are called __________ sequences. A. convergence B. idealized C. consensus D. common

C. consensus

During replication the 2 strands of the DNA molecule are unwound from one another by enzymes called A. ligases. B. unwindases. C. helicases. D. primases.

C. helicases

The unexpressed regions of split genes are called A. exons. B. endons. C. introns. D. codons.

C. introns

The Pribnow box of E. coli A. is centered approximately 35 bp upstream of the start site of transcription. B. is centered between 7 and 13 bp upstream of the start codon. C. is centered approximately 10 bp upstream of the start site of transcription. D. is located at the site of addition of poly (A) in eukaryotic mRNAs.

C. is centered approximately 10 bp upstream of the start site of transcription

Each chromosome has one or more __________ site(s) where replication begins. A. promoter B. replicon C. origin D. bifurcate

C. origin

A bacterial __________ is the nontranscribed region of the DNA to which RNA polymerase binds in order to initiate transcription. A. operon B. operator C. promoter D. initiator

C. promoter

When a DNA molecule is replicated, the daughter molecules contain one strand of parental DNA and one strand of newly synthesized DNA; this is called __________ replication. A. hemiconservative B. conservative C. semiconservative D. dispersive

C. semiconservative

The E. coli lac operon has ________ operator sequences. A. one B. two C. three D. four

C. three

Which of the following nitrogenous bases is usually found in RNA but not in DNA? A. adenine B. thymine C. uracil D. guanine

C. uracil

The energy needed for protein synthesis is provided by the hydrolysis of A. ATP. B. GTP. C. UTP. D. ATP and GTP. E. ATP and UTP.

D. ATP and GTP

Posttranscriptional modifications that yield eukaryotic mRNAs include which of the following? A. splicing to remove introns B. 5' poly (A) tracts C. 3' caps D. All of the choices

D. All of the choices

So-called two-component regulatory systems A. include a sensor kinase and a response regulator. B. play a key role in regulating sporulation in Bacillus. C. play a key role in regulating the OmpF and OmpC porin proteins in E. coli. D. all of the choices

D. all of the choices

Which of the following is true about the structure of DNA? A. Purine and pyrimidine bases are attached to the 1'-carbon of the deoxyribose sugars. B. Purine and pyrimidine bases are joined by phosphodiester bonds. C. Adjacent bases are stacked on top of each other, one base pair every 0.34 nm. D. all of the choices

D. all of the choices

Which of the following is in the coding region of a gene? A. promoter B. leader C. trailer D. none of the choices

D. none of the choices

Over twisting or under twisting of helical DNA generates A. hypertwists. B. hypotwists. C. hypercoils. D. supercoils.

D. supercoils

The process by which the base sequence of an RNA molecule is used to direct the synthesis of a protein is called A. replication. B. transcription. C. reverse transcription. D. translation.

D. translation

Hershey and Chase demonstrated that when the bacteriophage T2 infected its host cell, the __________ is injected into the host but the __________ remained outside.

DNA; protein

All prokaryotes initiate the synthesis of proteins with formylmethionine.

False

Because of its larger size, the replication rate of eukaryotic genomes is significantly faster than the replication rate of prokaryotic genomes.

False

DNA replication is a complex process, and as a result the frequency of error is quite high.

False

In the presence of both glucose and lactose, the lactose repressor is not bound to the operator and the genes of the lactose operon are expressed.

False

The binding of arabinose to the AraC protein allows it to form a loop in the DNA upstream of the ara operon promoter.

False

The real inducer for the E. coli lac operon is allolactose produced by the action of permease on lactose.

False

The stop codons are translated codons; that is, they specify amino acids to be inserted into the last position of a growing polypeptide chain.

False

Two-component signal transduction systems are found in the Bacteria, but not in Archaea.

False

____________ is used to measure the amount of a chemoattractant encountered over time.

Methylation

Bacterial chromosomes, unlike eukaryotic chromosomes, often consist of a single replicon

True

DNA functions as a storage molecule, holding genetic information for the lifetime of a cellular organism and allowing that information to be duplicated and passed on to its progeny.

True

Eukaryotic mRNAs are modified by addition of a poly(A) sequences at the 3' end and 7-methyl guanosine at the 5' end.

True

Gene regulation during sporulation in Bacillus subtilis involves BOTH temporal and spatial control.

True

Initiation of translation in eukaryotes is similar to that in prokaryotes except that more initiation factors are required in eukaryotes.

True

Small RNAs that regulate translation by binding to the leader region of mRNAs are called antisense RNAs.

True

Some microbial proteins are spliced after translation in a reaction that results in removal of one or more internal intervening sequences called inteins.

True

Split or interrupted genes have been found in eukaryotes but not in prokaryotes.

True

The B form of the DNA double helix contains a wider major groove and a narrower minor groove because the two polynucleotide strands are not positioned directly opposite one another in the helical cylinder.

True

The basic differences between RNA and DNA reside in their sugar and pyrimidine bases; RNA has ribose and uracil whereas DNA has deoxyribose and thymine.

True

The genetic code is usually translated in a nonoverlapping fashion.

True

The noncoding sequences located between the start codon and the stop codon in interrupted genes are called introns.

True

The protein coding sequences in interrupted genes are called exons.

True

When arabinose is present in the environment, the AraC protein acts as a(n) ______________ for the E. coli ara operon.

activator

Aminoacyl-tRNA synthetases catalyze covalent addition of __________ __________ to tRNAs.

amino acids

The two strands of a DNA molecule are __________; that is, they are oriented in opposite directions.

antiparallel

In order for high level expression of the E. coli lac operon to occur, a complex of catabolite activator protein and __________ must be bound to the DNA near the promoter.

cAMP

Proteins that recognize unfolded polypeptides and help them fold into their proper conformations are called ______________.

chaperones

The __________ describes the specific set of genes an organism possesses.

genotype

As prokaryotes normally only have one set of genes, they are called __________.

haploid

On mRNA molecules, a nontranslated sequence called the ___________ usually precedes the initiation codon.

leader

If a set of genes is repressed in the presence of the controlling substance, it is referred to as __________ control.

negative

The __________ is the collection of characteristics of an organism that an investigator observes.

phenotype

If a set of genes is induced in the presence of the controlling substance, it is referred to as __________ control.

positive

A collection of genes or operons controlled by a common regulatory protein is called a(n) ___________.

regulon

When there is no arabinose available in the environment, the AraC protein acts as a(n) ______________ for the E. coli ara operon.

repressor

Splicing of eukaryotic heteronuclear RNA is catalyzed by ______________.

snRNPs

mRNA molecules have a nontranslated sequence called the __________, which is located downstream of the termination codon.

trailer