Bio Chem Chapt 11

Question A transcription factor is

a protein other than RNA polymerase that is involved in transcription.

Question Response elements

are enhancers of transcription activated by metabolic factors

Ribosomes

are involved in protein synthesis.

Operons

are subject to positive or to negative control.

Question Which of the following is not a structural motif encountered in DNA-binding proteins?

b-barrel

Question Non-coding RNAs are known to:

bind to mRNA targeting them for destruction, bind to mRNA preventing their translation, promote RNA silencing

Question Transcription in eukaryotes differs from RNA synthesis in prokaryotes

by having multiple RNA polymerases rather than one.

Minor differences in the consensus sequence for RNA Polymerase

can be exploited to vary the amount of mRNA which is synthesized from that gene.

Which of the following best describes the order of events at the promoter?

closed complex ® open complex ® transcription initiation

Question Phosphorylation of the CTD of RNA polymerase II occurs during which phase of transcription?

conversion from the closed complex to the open complex

Question RNA polymerases from prokaryotes and eukaryotes

have sequence homology in catalytic subunits

Question Initiation of transcription in eukaryotes is primarily controlled

in the formation of the preinitiation complex

In prokaryotic RNA synthesis

inverted-repeat sequences in the DNA being transcribed can lead to termination

The enzyme principally responsible for RNA synthesis in Escherichia coli

is a multisubunit enzyme

Question RNA transcribed from the coding strand instead of the template strand

is called antisense RNA.

Control of transcription in prokaryotes does not involve

leucine zipper proteins.

Question In eukaryotes, which of the following types of RNA undergo some base modification after polymerization of the monomers?

mRNA, tRNA, rRNA,

Question As in prokaryotes, the regulatory regions for eukaryotic genes:

may be close to the genes they control, may be upstream of the genes they control, may be downstream of the genes they control

Question Proteins that recognize DNA with specific base sequences are

more likely to bind to the major groove.

A mutation in the lac A gene would result in

normal operation of the lac operon, but with an alteration in the proteins encoded by the lac A gene

Question Polyadenylation of eukaryotic mRNA

occurs at the 3' end.

Question Capping of eukaryotic mRNA

occurs at the 5' end.

Initiation of RNA biosynthesis involves

polymerase conversion of the closed-promoter complex to the open-promoter complex

Question The elongation and termination phases of eukaryotic transcription

require several protein factors

Consensus sequences are

sequences that have many bases in common

Question The eukaryotic TATA-binding protein (TBP) functions in a manner similar to

sigma (s) factor in E. coli.

Question Which of the following RNAs is noted for having a "cloverleaf" structure?

tRNA

Which of the following is not part of the core promoter?

the UP element

Which of the following is not a characteristic of catabolite activator protein (CAP)?

the binding of CAP to DNA requires ATP hydrolysis

Question The sequences in eukaryotic DNA known as introns are

the intervening sequences not expressed in the final sequence of messenger RNA

Question A commonly encountered feature of transfer RNA synthesis is

the precursor of several tRNA molecules is transcribed in one long polynucleotide sequence

The promoter site is

the site on DNA at which RNA polymerase binds to initiate transcription

Cyclic AMP affects transcription by

triggering the action of several protein factors

A single operon

usually contains all the enzymes which are specific for the synthesis of a special biomolecule.

RNA synthesis begins at the base in the DNA sequence designated by the following number:

+1 (plus one)

Question Where is the TATA box located?

-25 region.

Which is not associated with bacterial promoters?

3' antiterminator

Which of the following is the best description of an operon?

A group of genes under the control of a common promoter.

Which of the following offers the best description of a Pribnow box?

A promoter consensus sequence located at approximately -10.

What provides the energy for rho-dependent chain termination?

ATP hydrolysis distinct from any incorporation into the chain.

Question Which of the following is not a common modification occurring after polymerization of RNA?

Addition of phosphate to the bases.

At what point does the sigma (s) subunit of RNA polymerase released from the core enzyme?

After transcription begins and about 10 nucleotides have been added to the RNA chain.

Which of the following influence the amount of expression of an operon?

Availability of the specific sigma factor for that operon,How well the Pribnow box conforms to the consensus sequence, Attenuation mechanisms, Presence of 3' 5' cyclic AMP.

Which of the following correctly describes a difference between RNA & DNA polymerases?

DNA polymerases usually require a primer (i.e., they can only continue a strand, not start one), while most RNA polymerases do not.

Question How do eukaryotic and prokaryotic RNA polymerases compare?

Despite their added complexity, eukaryotic and prokaryotic RNA polymerases are generally homologous.

Chain termination occurs, in vivo, when:

Either a hairpin loop forms or rho (r) is involved.

How do enhancers differ from promoters?

Enhancers do not bind RNA polymerase.

Question Which of the following statements about the various RNA Polymerases in eukaryotes is false?

Eukaryotic RNA polymerases are generally monomeric.

Which of the following statements about eukaryotic and prokaryotic RNA polymerases, is false?

Eukaryotic polymerases have the same number of subunits as prokaryotic ones.

Question Post-transcription processing of mRNA in prokaryotes is required.

False

Question The leucine zipper is different from other DNA binding domains, since it requires the DNA-binding protein to form a dimer.

False

The end of the new mRNA molecule in E. coli. usually terminates in a string of A's

False

There is only one sigma subunit, since the same RNA Polymerase must bind to all genes in E. coli.

False

Question Which category of ribozymes requires an external guanosine frothier action?

Group I

What is the function of the sigma (s) subunit of RNA polymerase in E. coli?

It recognizes promoters where transcription should begin.

Which of the following is not a property of the sigma (s) subunit?

It stays with the RNA Pol throughout synthesis.

Question CREB contains the following structural motif:

Leucine zipper

Question Which ends of prokaryotic mRNA are protected from degradation?

Neither end

Question TATA-binding protein (TBP) is required for transcription by

Pol I. Pol II. Pol III.

Question Which of the following is not true?

RNA Pol IV is the primary RNA synthesizer in plants

Which enzyme transcribes genes encoding tRNA in eukaryotes?

RNA polymerase III

Which of the following does not influence the timing of expression of an operon?

Repressors

Question Splicing reactions for exons involve the following mechanisms, except:

Small nuclear RNAs, Ribozymes, Lariat mechanisms, Participation of special G residues

Which of following statements concerning RNA transcription is false?

Synthesis of RNA is as accurate as synthesis of DNA

Question Which of the following transcription factors is involved in the elongation phase of eukaryotic transcription?

TFIIF

Which of the following is true concerning the first nucleotide incorporated into an RNA chain?

The first nucleotide incorporated into the RNA chain retains its 5'-triphosphate

How do the core enzyme and the holoenzyme of RNA polymerase differ in E. coli?

The holoenzyme includes the sigma (s) subunit, the core enzyme does not.

All of the following apply to attenuation mechanisms, except:

The rate of RNA synthesis is regulated by the conformation of the protein being synthesized.

What is the need for a primer strand in transcription?

There is none.

Question Which of the following best describes leucine zipper motifs?

They allow protein-protein interactions via hydrophobic bonds.

Question Which of the following is true about micro RNAs?

They are a type of non-coding RNA

Which of the following is true about riboswitches:

They have a molecule sensing domain called an aptamer,There are known pathogens that use riboswitches as part of their mechanism, They respond to specific molecules and control translation in a way that is often similar to transcription attenuation, They contain a sensing domain and a decision making domain

What provides the energy for the conversion from the open complex to chain elongation?

Torsional stress built into the separating DNA strands.

Which of following statements concerning RNA transcription is false?

Transcription requires the use of a primer.

Question Alternative removal of exons from mRNA is important in which of the following?

Troponins and other contractile proteins, Different types of collagen, The disease lupus, Alzheimer's disease.

Attenuation mechanisms rely on alternative secondary structures forming in the mRNA

True

Inducers allow for a system in which an enzyme is not made unless it is needed.

True

Inducers for operons are often structurally related to the enzyme substrates of that operon.

True

Question Alternative splicing of exons is a mechanism to get more than 1 protein from the same gene.

True

Question DNA binding domains are distinct from transcription-activation domains.

True

Question Intracellular levels of cyclic AMP can affect the phosphorylation of proteins and enzymes as a secondary messenger.

True

Question One rather unusual transcription factor in eukaryotes halts RNA synthesis to allow for repair of damaged DNA.

True

Question Ribozymes, the catalytic activity of RNA, were first discovered as part of the snRNA group.

True

Question The lariat mechanism has been demonstrated by observing the lariat structure using electron microscopy.

True

Question The major difference between RNA initiation in eukaryotes and prokaryotes is the number of factors involved in the process.

True

The catabolite activator protein can overcome the effect of a repressor binding to the operon.

True

The weakness of A-U base pairs at the end of the RNA molecule may help in dissociation of the new RNA product.

True

Which of the following is not a key step in the activation of mRNA synthesis in eukaryotes?

Binding of RNA Pol I.

Question Which ends of eukaryotic mRNA are protected from degradation?

Both ends

Which of following statements describes a difference between replication of DNA and transcription of RNA?

Both strands of DNA are copied in replication, but usually only one is copied in transcription.

Which of these terms does not describe the DNA strand used to direct RNA synthesis?

Coding strand