exam 2 review

How many promoters are in an operon? A) 1 B) 2 C) 3 D) It depends on how many genes are present in the operon

A) 1

This pre-mRNA contains 8 exons and 7 introns. The splice sites surrounding exon 4 are not readily recognized by the splicesome. In addition, a splicing repressor prevents the recognition of the 3' splice site in exon 7. What exons will be present in the mature mRNA? A) 1, 2, 3, 5, 6, 8 B) 1, 2, 3, 4, 5, 6, 7, 8 C) 1, 2, 3, 4, 5, 6, 8 D) 1, 2, 3, 5, 6, 7, 8 E) 1, 2, 3, 5, 6

A) 1, 2, 3, 5, 6, 8

What is the purpose of phosphorylating the carboxy terminal domain (CTD)? A) Convert from initiation to the elongation stage B) To aid in transcriptional initiation C) Phosphorylate transcription factors D) To aid in promoter recognition

A) Convert from initiation to the elongation stage

How are eukaryotic transcription factors regulated? (Check all that apply.) A) Covalent modification B) Binding to cytoskeletal elements C) Binding of an effector molecule D) Protein-protein interaction

A) Covalent modification C) Binding of an effector molecule D) Protein-protein interaction

Select the two primary components of chromatin. A) DNA B) Proteins C) RNA D) Lipids E) Carbohydrates

A) DNA B) Proteins

Which region of DNA contains the coding information for a protein in a eukaryote? A) Exons B) Introns C) Enhancers D) Promoters

A) Exons

If a bacteria is placed in an environment that contains both glucose and lactose, the regulation of the lac operon will allow which nutrient to be processed first? A) Glucose B) Lactose C) Both will be processed equally D) Neither will be processed in this environment

A) Glucose

Which of the following encode polycistronic mRNA? (Check all that apply.) A) Lac operon B) Operator site C) Trp operon D) CAP site

A) Lac operon C) Trp operon

In the Igf-2 allele, which chromosome is imprinted? Which is expressed? A) Paternal; paternal B) Paternal; maternal C) Maternal; paternal D) Maternal; maternal

A) Paternal; paternal

Where does the process of transcription initiate? A) Promoter B) Terminator C) Regulation sequences D) Transcription factors

A) Promoter

DNA topoisomerase I does which of the following? A) Relaxes negative supercoils B) Relaxes positive supercoils C) Introduces negative supercoils D) More than one of these choices are correct.

A) Relaxes negative supercoils

If the Trp codons in the trpL gene were mutated to encode another amino acid, what would the result be? A) The trp operon would never be transcribed. B) The trp operon would always be transcribed. C) The trp operon would only be transcribed when tryptophan in the cell was low. D) The trp operon would only be transcribed when tryptophan in the cell was high.

A) The trp operon would never be transcribed.

What snRNP binds to the 5' splice site and is released after the 5' end of the intron is attached to the branch site? A) U1 B) U2 C) U5 D) U6

A) U1

A chromosome territory is defined as __________. A) a region in the nucleus that is occupied by a single chromosome B) a region on a chromosome that is devoid of nucleosomes C) a region on a chromosome that has no protein encoding genes D) a region in the nucleus that may have several chromosomes

A) a region in the nucleus that is occupied by a single chromosome

In the presence of abundant iron in the cell, the iron binds IRP. The complex is then released from IREs leading to __________. A) an increase in ferritin mRNA translation and a decrease in transferrin receptor mRNA stability B) an increase in transferrin receptor mRNA stability and a decrease in ferritin mRNA translation C) an increase in transferrin receptor mRNA stability and ferritin mRNA translation D) an decrease in transferrin receptor mRNA stability and ferritin mRNA translation

A) an increase in ferritin mRNA translation and a decrease in transferrin receptor mRNA stability

A main function of TFIID is __________. A) to recognize the TATA box B) to act as a helicase C) to terminate RNA polymerase II binding D) to phosphorylate the CTD of RNA polymerase II

A) to recognize the TATA box

What is the gene responsible for attenuation in the trp operon? A) trpL B) trpR C) trpD D) trpC

A) trpL

wobble rules

According to the wobble rules, the first two positions pair strictly according to the AU/GC rule. However, the third position can tolerate certain types of mismatches. e.g., If the third base of the mRNA codon is C, the complementary base in the anticodon can be G, A, or I.

About how many bases of DNA wrap around a histone complex? A) < 50 B) 150 C) 200 D) > 1,000

B) 150

1) Taking into account your knowledge of wobble rules, select all anticodons that can pair with the codon 5'-UAC-3'. (Check all that apply.) A) 5'-AUG-3' B) 5'-IUA-3' C) 5'-AUA-3' D) 5'-GUA-3' E) 5'-GUI-3'

B) 5'-IUA-3' C) 5'-AUA-3' D) 5'-GUA-3'

Which of the following is part of the process of X chromosome inactivation? A) Expression of Xist from both chromosomes at the start of the process B) Binding of multiple Xist transcripts to Xic on the X chromosome that will be inactivated C) Compaction of the active X chromosome into a Barr body D) Binding of Tsix transcripts to the X chromosome to be inactivated after the Xist transcripts binds to Xic

B) Binding of multiple Xist transcripts to Xic on the X chromosome that will be inactivated

CpG islands are associated with which of the following? A) Nucleosome location B) DNA methylation C) Steroid hormone activity D) Termination of translation

B) DNA methylation

CpG islands are associated with which of the following? A) Nucleosome location B) DNA methylation C) Steroid hormone activity D) cAMP pathway

B) DNA methylation

Most imprinted genes are silenced. What is one exception to this rule? A) H19 B) Igf-2 C) Xist D) Tsix

B) Igf-2

In eukaryotic organisms, the processing of the 45S rRNA into 5.8S, 18S, and 28S rRNA occurs where? A) In the cytoplasm B) In the nucleolus C) In the endoplasmic reticulum D) In the Golgi body E) Throughout the cell

B) In the nucleolus

What is a mechanism of condensation shared by both prokaryotes and eukaryotes? A) Nucleosomes B) Loop domains C) 30 nm fiber D) None of these choices are correct.

B) Loop domains

Select the events that are part of the mechanism for epigenetic regulation of the Igf2 gene. (Choose all that apply.) A) Methylation of the H19 locus B) Methylation of the ICR and DMR domains C) Binding of CTCFs to methylated sequences D) Methylation of CTCFs

B) Methylation of the ICR and DMR domains C) Binding of CTCFs to methylated sequences

Which of the following recognizes response elements, control elements, and regulatory elements? A) General transcription factors B) Regulatory transcription factors C) Mediator D) Transactivation domains

B) Regulatory transcription factors

What general transcription factor is most often affected by regulatory transcription factors? A) TFIIB B) TFIID C) TFIIE D) TFIIF

B) TFIID

What basal transcription factor is a helicase? A) TFIID B) TFIIH C) TFIIF D) TFIIB

B) TFIIH

What gene is most responsible for X-inactivation? A) Xic B) Xist C) Tsix D) Xce

B) Xist

The C-terminus of a polypeptide always contains __________. A) a stop codon B) a carboxyl group C) an amino group D) carbon dioxide E) None of these choices are correct.

B) a carboxyl group

Feeding a specific diet to female mice may result in an increased proportion of pseudoagouti offspring if __________. A) the female carries the Avy allele B) the offspring have the genotype Avya C) the transposon at the Avy locus in the progeny is hypermethylated

B) the offspring have the genotype Avya C) the transposon at the Avy locus in the progeny is hypermethylated

Antisense RNA does which of the following? A) Inhibits the formation of the open complex in transcription B) Occupies the A and P sites of the ribosome C) Binds to the mRNA and prevents translation D) Prevents the correct folding of a newly formed peptide

C) Binds to the mRNA and prevents translation

Histone acetyltransferases are directly involved in which of the following? A) Removal of histones from chromatin B) Movement of nucleosomes C) Chemical modification of histones D) Termination of gene expression E) Insertion of variant histone proteins

C) Chemical modification of histones

A nucleosome is a combination of __________ and __________. A) histone proteins; scaffold proteins B) RNA; transcription proteins C) DNA; histone proteins D) RNA; histone proteins E) DNA; scaffold proteins

C) DNA; histone proteins

What site does the initiator tRNA bind to on the ribosome? A) A B) E C) P

C) P

What site on the ribosome is primarily responsible for holding the growing polypeptide? A) A B) E C) P

C) P

A gene that undergoes rho-dependent termination has a mutation in the rut site. How will this influence transcriptional activity? A) Transcription will terminate normally as Rho termination relies on the rut site to enhance termination; it is not essential for termination B) Transcription will stop immediately because RNA polymerase will sense there is a mutation C) Transcription will continue until another termination sequence, either Rho dependent or independent is reached D) There will be no transcription initiation

C) Transcription will continue until another termination sequence, either Rho dependent or independent is reached

1) If CAP could not bind to its CAP site, then what would be the result? Assume lactose is present in each scenario. A) Transcription would be difficult to repress in the presence of glucose B) Transcription would be difficult to activate in the presence of glucose C) Transcription would be difficult to activate in the absence of glucose

C) Transcription would be difficult to activate in the absence of glucose

Allosteric regulation is accomplished by __________. A) a small molecule that fits into an enzyme's active site B) a large protein that blocks an enzyme's active site C) a small molecule that fits into a site on the enzyme that is not the active site d) a small molecule that covalently modifies a site on the enzyme that is not the active

C) a small molecule that fits into a site on the enzyme that is not the active site

Which RNA encodes the sequence of amino acids for a functional protein? A) tRNA B) snRNA C) mRNA D) rRNA E) scRNA

C) mRNA

RF1 and RF2 are active during _______. A) initiation B) elongation C) termination D) peptidyl transfer

C) termination

The peptidyl transferase is a component of __________. A) DNA B) tRNA C) the ribosome D) the protein being translated E) mRNA

C) the ribosome

1) What stem-loop conformations favor attenuation? A) 1-2 B) 1-2 and 2-3 C) 2-3 D) 1-2 and 3-4

D) 1-2 and 3-4

What gene(s) is/are encoded in the Xic? A) Xce B) Xist C) Tsix D) Both the Tsix and Xist are genes are in the Xic region

D) Both the Tsix and Xist are genes are in the Xic region

What do both the rho-dependent and rho-independent mechanisms of termination have in common? A) Terminate transcription immediately after the stop codon B) A sequence rich with A-U base pairs C) Both require a helicase to separate the DNA-RNA complex D) Formation of a stem-loop structure

D) Formation of a stem-loop structure

Which of the following represents the lowest level of chromosome condensation? A) Radial loop domain B) 30 nm fibers C) Heterochromatin D) Nucleosome E) Euchromatin

D) Nucleosome

What modification acts to stabilize eukaryotic mRNA? A) Alternative splicing B) RNA editing C) RNA interference D) Polyadenylation E) Trimming

D) Polyadenylation

Which molecules are not part of the closed complex? A) RNA polymerase B) Transcription factors C) Double helix DNA D) Single-stranded DNA

D) Single-stranded DNA

What typically terminates the process of translation? A) Rho proteins B) Aminoacyl tRNA synthase C) rRNA D) Stop codons E) Introns

D) Stop codons

Where does mRNA/tRNA codon-anticodon recognition take place? A) 30S B) 40S C) 50S D) The surface between the two ribosomal subunits

D) The surface between the two ribosomal subunits

A tRNA that has an amino acid attached is called __________. A) an rRNA B) a degenerate tRNA C) a coding tRNA D) a charged tRNA

D) a charged tRNA

In the lac operon, the CAP site is located next to the __________. When both lactose and glucose are present, this leads to a rate of transcription that is __________. A) terminator; low B) promoter; high C) terminator; high D) promoter; low

D) promoter; low

An anticodon is located on __________. A) DNA B) mRNA C) rRNA D) tRNA E) snRNA

D) tRNA

The RNA transcript is complementary to __________. A) regulatory sequences B) termination sequences C) the coding strand of DNA D) the template strand of DNA

D) the template strand of DNA

What sequences are not considered to be regulatory elements? A) Enhancers B) Silencers C) Core promoters D) Cis-acting elements E) General transcription factors

E) General transcription factors

A mutation occurs in one of the general transcription factors necessary for eukaryotic transciption. A pre-intiation complex forms, but the open complex does not form. Further, TFIIB, TFIIE, and TFIIH are not released from the DNA. The mutation is most likely in which general transcription factor? A) TFIIB B) TFIID C) TFIIE D) TFIIF E) TFIIH

E) TFIIH

splicing info

If all exons were included, the mature mRNA would contain exons 1, 2, 3, 4, 5, 6, 7, 8. However, because the splice sites surronding exon 4 are not well recognized by the splicesome, it is not included. Similarly, a repressor binding to the 3' splice site of exon 7 will block its inclusion. Therefore the final mature mRNA will contain exons 1, 2, 3, 5, 6, 8.

trp codes

If there were not Trp codons in the trpL mRNA, the ribosome would never pause within region 1 of the mRNA. Translation of the trpL mRNA would progress to its stop codon, where the ribosome would pause. This pausing prevents region 2 from forming a stem loop. Region 3 hydrogen bonds with region 4, which terminates transcription of the rest of the trp operon.

transcription factor info

TFIIH is the general transcription factor that acts as a helicase to form an open complex. TFIIH also phosphorylates the CTD of RNA Pol II, leading to the release of TFIIB, TFIIE, and TFIIH. If these things are not occurring, it is mostly likely because of a mutation in TFIIH.

glucose and cAMP

When glucose is low, cAMP is high, and cAMP binds to CAP, which then binds to the CAP site and enhances transcription. If CAP could not bind to the CAP site, it would be difficult to achieve a high rate of transcription in the absence of glucose.

1) In the lac operon, the operator site is recognized by an activator protein. ⊚ true ⊚ false

false

Activator proteins bind to silencer sequences and repressor proteins bind to enhancer sequences. ⊚ true ⊚ false

false

In eukaryotes, enhancers must be close to the promoter to have an effect. ⊚ true ⊚ false

false

Overwinding of the DNA decreases the number of turns in the double helix, and thus results in supercoils in the DNA. ⊚ true ⊚ false

false

Nucleosome location may be changed by a process called ATP-dependent chromatin remodeling. ⊚ true ⊚ false

true

Steroid hormones are an example of an effector which regulates regulatory transcription factor activity. ⊚ true ⊚ false

true

A repressor protein would enhance the ability of TFIID to bind to the TATA box of the promoter. ⊚ true ⊚ false

⊚ false

A riboswitch only affects translation of an operon. ⊚ true ⊚ false

⊚ false

DNA methylation usually activates gene expression. ⊚ true ⊚ false

⊚ false

The formation of an open complex occurs at GC rich regions of DNA due to the decreased number of hydrogen bonds. ⊚ true ⊚ false

⊚ false

Because of alternative splicing, a pre-mRNA could generate a dozen different mRNAs. ⊚ true ⊚ false

⊚ true

During elongation, the polypeptide is removed from the tRNA in the P site and transferred to the amino acid in the A site. ⊚ true ⊚ false

⊚ true

During the initiation phase of transcription the sigma (σ) factor, which is bound to RNA polymerase, binds into the major groove of DNA and recognizes sequence elements at the promoter. This process forms a closed complex. ⊚ true ⊚ false

⊚ true

One would expect heterochromatic regions of DNA to be more compacted than euchromatic regions. ⊚ true ⊚ false

⊚ true

The 30-nm fiber is formed from arrays of nucleosomes. ⊚ true ⊚ false

⊚ true

The activity of some transcription factors can be regulated by covalent modifications. ⊚ true ⊚ false

⊚ true

The term ribozyme is given to catalytic RNA molecules. ⊚ true ⊚ false

⊚ true

Transcription and translation may occur simultaneously in prokaryotic cells. ⊚ true ⊚ false

⊚ true