Question 1

Describe in words (not using structures)the important features of the structures present on the 5' and 3' ends of mature (processed)eukaryotic mRNAs.

Accepted Answer

At the 5' end,there is a cap consisting of a guanosine joined to the 5'-terminal nucleotide through a 5' to 5' triphosphate group.This guanine nucleotide is methylated on N-7.The next two nucleotides in the chain are also sometimes methylated on their 2'-OH groups.At the 3' end is the poly(A)tail consisting of a run of 80-250 adenylate residues.

Question 2

Which of the following is not a known function of TFIIH?

Accepted Answer

A) DNA helicase activity. 
B) Hydrolysis of ATP. 
C) Formation of an open complex 
D) Termination of transcription 
E) Nucleotide excision repair 
A) DNA helicase activity. 
B) Hydrolysis of ATP. 
C) Formation of an open complex 
D) Termination of transcription 
E) Nucleotide excision repair D

Question 3

Processing of a primary mRNA transcript in a eukaryotic cell does not normally involve:

Accepted Answer

A) attachment of a long poly(
A) sequence at the 3' end. 
B) conversion of normal bases to modified bases,such as inosine and pseudouridine. 
C) excision of intervening sequences (introns). 
D) joining of exons. 
E) methylation of one or more guanine nucleotides at the 5' end. 
A) attachment of a long poly(
A) sequence at the 3' end. 
B) conversion of normal bases to modified bases,such as inosine and pseudouridine. 
C) excision of intervening sequences (introns). 
D) joining of exons. 
E) methylation of one or more guanine nucleotides at the 5' end. B

Question 4

Which one of the following properties of the L-19 IVS ribozyme is not shared with enzymes that are purely protein?

Accepted Answer

A) It acts as a true catalyst. 
B) It can be competitively inhibited. 
C) It displays Michaelis-Menten kinetics. 
D) It exploits base pairing with internal guide sequences. 
E) It makes use of covalent and metal ion catalysis. 
A) It acts as a true catalyst. 
B) It can be competitively inhibited. 
C) It displays Michaelis-Menten kinetics. 
D) It exploits base pairing with internal guide sequences. 
E) It makes use of covalent and metal ion catalysis.

Question 5

What is the utility of the SELEX protocol and how does it work?

Accepted Answer

SELEX is "accelerated evolution in a tes

Question 6

Which of the following is not known to be involved in initiation by eukaryotic RNA polymerase II?

Accepted Answer

A) DNA helicase activity 
B) DNA polymerase activity 
C) Formation of an open complex 
D) Protein binding to specific DNA sequences 
E) Protein phosphorylation 
A) DNA helicase activity 
B) DNA polymerase activity 
C) Formation of an open complex 
D) Protein binding to specific DNA sequences 
E) Protein phosphorylation

Question 7

Rifampicin blocks RNA polymerase;why would this be lethal to a cell that was sensitive to this drug?

Accepted Answer

Without RNA synthesis, there could be no

Question 8

Compare transcription and reverse transcription in terms of the following characteristics:
(a)Direction of polynucleotide synthesis
(b)Nature of template
(c)Nature of primer
(d)Incorporated nucleotides

Accepted Answer

The answer of Compare transcription and reverse transcription in terms...

Question 9

The sigma factor of E.coli RNA polymerase:

Accepted Answer

A) associates with the promoter before binding core enzyme. 
B) combines with the core enzyme to confer specific binding to a promoter. 
C) is inseparable from the core enzyme. 
D) is required for termination of an RNA chain. 
E) will catalyze synthesis of RNA from both DNA template strands in the absence of the core enzyme. 
A) associates with the promoter before binding core enzyme. 
B) combines with the core enzyme to confer specific binding to a promoter. 
C) is inseparable from the core enzyme. 
D) is required for termination of an RNA chain. 
E) will catalyze synthesis of RNA from both DNA template strands in the absence of the core enzyme.

Question 10

Write the sequence of the messenger RNA molecule synthesized from a DNA template strand having the sequence:
(5')ATCGTACCGTTA(3')

Accepted Answer

(3')UAGCAUGGCAAU(5')

Question 11

Reverse transcriptase:

Accepted Answer

A) can utilize only RNA templates. 
B) has a 3' $\rightarrow$ 5' proofreading exonuclease but not a 5' $\rightarrow$ 3' exonuclease. 
C) is activated by AZT. 
D) is encoded by retroviruses. 
E) synthesizes DNA with the same fidelity as a typical DNA polymerase. 
A) can utilize only RNA templates. 
B) has a 3' $\rightarrow$ 5' proofreading exonuclease but not a 5' $\rightarrow$ 3' exonuclease. 
C) is activated by AZT. 
D) is encoded by retroviruses. 
E) synthesizes DNA with the same fidelity as a typical DNA polymerase.

Question 12

Compare and contrast $\rho$-dependent and $\rho$-independent termination of transcription in prokaryotes.

Accepted Answer

In both,the transcription complex pauses

Question 13

Indicate whether each of the following statements about eukaryotic cells is true (T)or false (F).
___ They have three distinct RNA polymerases.
___ Their mRNAs are generally synthesized by RNA polymerase I.
___ RNA polymerase III synthesizes only rRNAs.
___ The 5S rRNA is synthesized by RNA polymerase I
___ Their RNA polymerases initiate transcription at specific promoter sites on the DNA

Accepted Answer

A) True 
 B)False

Question 14

Which one of the following statements about mRNA stability is true?

Accepted Answer

A) Degradation always proceeds in the 5' to 3' direction. 
B) Degradation of mRNA by polynucleotide phosphorylase yields 5'-nucleoside monophosphates. 
C) In general,bacterial mRNAs have longer half-lives than do eukaryotic mRNAs. 
D) Rates of mRNA degradation are always at least 10-fold slower than rates of mRNA synthesis. 
E) Secondary structure in mRNA (hairpins,for example)slows the rate of degradation. 
A) Degradation always proceeds in the 5' to 3' direction. 
B) Degradation of mRNA by polynucleotide phosphorylase yields 5'-nucleoside monophosphates. 
C) In general,bacterial mRNAs have longer half-lives than do eukaryotic mRNAs. 
D) Rates of mRNA degradation are always at least 10-fold slower than rates of mRNA synthesis. 
E) Secondary structure in mRNA (hairpins,for example)slows the rate of degradation.

Question 15

Which one of the following statements about the reverse transcriptases of retroviruses and the RNA replicases of other single-stranded RNA viruses,such as R17 and influenza virus,is correct?

Accepted Answer

A) Both enzymes can synthesize either RNA or DNA from an RNA template strand. 
B) Both enzymes can utilize DNA in addition to RNA as a template strand. 
C) Both enzymes carry the specificity for the RNA of their own virus. 
D) Both enzymes have error rates similar to those of cellular RNA polymerases. 
E) Both enzymes require host-encoded subunits for their replication function. 
A) Both enzymes can synthesize either RNA or DNA from an RNA template strand. 
B) Both enzymes can utilize DNA in addition to RNA as a template strand. 
C) Both enzymes carry the specificity for the RNA of their own virus. 
D) Both enzymes have error rates similar to those of cellular RNA polymerases. 
E) Both enzymes require host-encoded subunits for their replication function.

Question 16

Which of the following statements about the synthesis of rRNA and tRNA in E.coli is true?

Accepted Answer

A) Both rRNA and some tRNAs are part of the same primary transcript. 
B) Each rRNA sequence (16S,23S,5S)is transcribed as a separate primary transcript. 
C) Primary tRNA transcripts undergo methylation,but rRNA sequences are not methylated. 
D) The tRNA sequences all lie at the 3'end of the rRNA transcripts. 
E) There is a single copy of the rRNA genes. 
A) Both rRNA and some tRNAs are part of the same primary transcript. 
B) Each rRNA sequence (16S,23S,5S)is transcribed as a separate primary transcript. 
C) Primary tRNA transcripts undergo methylation,but rRNA sequences are not methylated. 
D) The tRNA sequences all lie at the 3'end of the rRNA transcripts. 
E) There is a single copy of the rRNA genes.

Question 17

Compared with DNA polymerase,reverse transcriptase:

Accepted Answer

A) does not require a primer to initiate synthesis. 
B) introduces no errors into genetic material because it synthesizes RNA,not DNA. 
C) makes fewer errors in synthesizing a complementary polynucleotide. 
D) makes more errors because it lacks the 3' $\rightarrow$5' proofreading exonuclease activity. 
E) synthesizes complementary strands in the opposite direction-from 3' $\rightarrow$ 5'. 
A) does not require a primer to initiate synthesis. 
B) introduces no errors into genetic material because it synthesizes RNA,not DNA. 
C) makes fewer errors in synthesizing a complementary polynucleotide. 
D) makes more errors because it lacks the 3' $\rightarrow$5' proofreading exonuclease activity. 
E) synthesizes complementary strands in the opposite direction-from 3' $\rightarrow$ 5'.

Question 18

Which of the following is not true about telomerase?

Accepted Answer

A) Telomerase is a reverse transcriptase. 
B) Telomerase utilizes a tRNA template. 
C) The primer for telomerase is the 3'-end of the DNA chromosomes. 
D) Telomerase synthesizes DNA in the 5' $\rightarrow$3' direction. 
E) Telomerase consists of both RNA and protein. 
A) Telomerase is a reverse transcriptase. 
B) Telomerase utilizes a tRNA template. 
C) The primer for telomerase is the 3'-end of the DNA chromosomes. 
D) Telomerase synthesizes DNA in the 5' $\rightarrow$3' direction. 
E) Telomerase consists of both RNA and protein.

Question 19

The specific sequences that E.coli RNA polymerase usually binds to in E.coli DNA before initiating transcription generally contain more A=T base pairs than G$ \equiv$C base pairs.In no more than a few sentences,speculate on why this might be the case.

Accepted Answer

Because A=T base pairs are stabilized by

Question 20

RNA polymerase:

Accepted Answer

A) binds tightly to a region of DNA thousands of base pairs away from the DNA to be transcribed. 
B) can synthesize RNA chains without a primer. 
C) has a subunit called $\lambda$ (lambda),which acts as a proofreading ribonuclease. 
D) separates DNA strands throughout a long region of DNA (up to thousands of base pairs),then copies one of them. 
E) synthesizes RNA chains in the 3' $\rightarrow$ 5' direction. 
A) binds tightly to a region of DNA thousands of base pairs away from the DNA to be transcribed. 
B) can synthesize RNA chains without a primer. 
C) has a subunit called $\lambda$ (lambda),which acts as a proofreading ribonuclease. 
D) separates DNA strands throughout a long region of DNA (up to thousands of base pairs),then copies one of them. 
E) synthesizes RNA chains in the 3' $\rightarrow$ 5' direction.

Exam 26: Rna Metabolism

Describe in words (not using structures)the important features of the structures present on the 5' and 3' ends of mature (processed)eukaryotic mRNAs.

Which of the following is not a known function of TFIIH?

Processing of a primary mRNA transcript in a eukaryotic cell does not normally involve:

Which one of the following properties of the L-19 IVS ribozyme is not shared with enzymes that are purely protein?

What is the utility of the SELEX protocol and how does it work?

Which of the following is not known to be involved in initiation by eukaryotic RNA polymerase II?

Rifampicin blocks RNA polymerase;why would this be lethal to a cell that was sensitive to this drug?

Compare transcription and reverse transcription in terms of the following characteristics: (a)Direction of polynucleotide synthesis (b)Nature of template (c)Nature of primer (d)Incorporated nucleotides

The sigma factor of E.coli RNA polymerase:

Write the sequence of the messenger RNA molecule synthesized from a DNA template strand having the sequence: (5')ATCGTACCGTTA(3')

Reverse transcriptase:

Compare and contrast ρ\rhoρ -dependent and ρ\rhoρ -independent termination of transcription in prokaryotes.

Which one of the following statements about mRNA stability is true?

Which one of the following statements about the reverse transcriptases of retroviruses and the RNA replicases of other single-stranded RNA viruses,such as R17 and influenza virus,is correct?

Which of the following statements about the synthesis of rRNA and tRNA in E.coli is true?

Compared with DNA polymerase,reverse transcriptase:

Which of the following is not true about telomerase?

The specific sequences that E.coli RNA polymerase usually binds to in E.coli DNA before initiating transcription generally contain more A=T base pairs than G ≡ \equiv≡ C base pairs.In no more than a few sentences,speculate on why this might be the case.

RNA polymerase:

The Foundations of Biochemistry

Water

Amino Acids, peptides, and Proteins

The Three-Dimensional Structure of Proteins

Protein Function

Enzymes

Carbohydrates and Glycobiology

Nucleotides and Nucleic Acids

Recombinant Dna Technology

Lipids

Biological Membranes and Transport

Biosignaling

Principles of Bioenergetics

Glycolysis, gluconeogenesis, and the Pentose Phosphate Pathway

Principles of Metabolic Regulation

The Citric Acid Cycle

Fatty Acid Catabolism

Amino Acid Oxidation and the Production of Urea

Oxidative Phosphorylation and Photophosphorylation

Carbohydrate Biosynthesis in Plants and Bacteria

Lipid Biosynthesis

Biosynthesis of Amino Acids, nucleotides, and Related Molecules

Integration and Hormonal Regulation of Mammalian Metabolism

Genes and Chromosomes

Dna Metabolism

Protein Metabolism

Regulation of Gene Expression

Filters

Compare and contrast $\rho$ -dependent and $\rho$ -independent termination of transcription in prokaryotes.

The specific sequences that E.coli RNA polymerase usually binds to in E.coli DNA before initiating transcription generally contain more A=T base pairs than G $\equiv$ C base pairs.In no more than a few sentences,speculate on why this might be the case.