Question 1

Which of the following statements about E.coli RNA polymerase is false?

Accepted Answer

A) Core enzyme selectively binds promoter regions,but cannot initiate synthesis without a sigma factor. 
B) RNA polymerase holoenzyme has several subunits. 
C) RNA produced by this enzyme will be completely complementary to the DNA template. 
D) The enzyme adds nucleotides to the 3' end of the growing RNA chain. 
E) The enzyme cannot synthesize RNA in the absence of DNA. 
A) Core enzyme selectively binds promoter regions,but cannot initiate synthesis without a sigma factor. 
B) RNA polymerase holoenzyme has several subunits. 
C) RNA produced by this enzyme will be completely complementary to the DNA template. 
D) The enzyme adds nucleotides to the 3' end of the growing RNA chain. 
E) The enzyme cannot synthesize RNA in the absence of DNA.

Question 2

Transfer RNAs have several bases in addition to the normal four found in RNA.How are these rare bases incorporated into the tRNA molecule?

Accepted Answer

The unusual bases in tRNA are

Question 3

Which of the following statements about E.coli RNA polymerase (core enzyme)is false?

Accepted Answer

A) In the absence of the $\sigma$subunit,core polymerase has little specificity for where initiation begins. 
B) The core enzyme contains several different subunits. 
C) The core enzyme has no polymerizing activity until the $\sigma$ subunit is bound. 
D) The RNA chain grows in a 5' $\rightarrow$  3' direction. 
E) The RNA product is complementary to the DNA template. 
A) In the absence of the $\sigma$subunit,core polymerase has little specificity for where initiation begins. 
B) The core enzyme contains several different subunits. 
C) The core enzyme has no polymerizing activity until the $\sigma$ subunit is bound. 
D) The RNA chain grows in a 5' $\rightarrow$  3' direction. 
E) The RNA product is complementary to the DNA template.

Question 4

Describe the function of polyadenylate polymerase and name two properties that distinguish it from normal cellular RNA polymerases.

Accepted Answer

Poly(A)polymerase is required to add the

Question 5

Name four general types of posttranscriptional processing reactions that are observed in RNA.Briefly (one sentence or less)point out an example of each type.In your example,identify the type of RNA molecule involved (tRNA,mRNA,rRNA,etc. ),the type of "processing" involved,and whether the example is characteristic of eukaryotes or prokaryotes,or both.Do not describe specific genes,sequences,complicated structures,or enzymes.

Accepted Answer

Posttranscriptional reactions on mRNA in

Question 6

Aptamers are:

Accepted Answer

A) double-stranded RNA products of nuclease action on hairpin RNAs. 
B) repeat sequence elements at the ends of transposons. 
C) small RNA molecules selected for tight binding to specific molecular targets. 
D) the RNA primers required for retroviral replication. 
E) the short tandem repeat units found in telomeres. 
A) double-stranded RNA products of nuclease action on hairpin RNAs. 
B) repeat sequence elements at the ends of transposons. 
C) small RNA molecules selected for tight binding to specific molecular targets. 
D) the RNA primers required for retroviral replication. 
E) the short tandem repeat units found in telomeres.

Question 7

Which of the following is (are)characteristic of $\rho$-independent termination of RNA transcription in E.coli?

Accepted Answer

A) The RNA transcript contains self-complementary sequences. 
B) Three conserved A's in the template strand near the end of the transcript. 
C) A CA-rich sequence near the end of the transcript. 
D) Both A and B 
E) Both A and C 
A) The RNA transcript contains self-complementary sequences. 
B) Three conserved A's in the template strand near the end of the transcript. 
C) A CA-rich sequence near the end of the transcript. 
D) Both A and B 
E) Both A and C

Question 8

For each of the following statements,indicate with a P if the statement applies only to prokaryotes,an E if the statement applies only to eukaryotes,and an E and P if the statement applies to both eukaryotes and prokaryotes.
___ RNA synthesis is blocked by actinomycin D.
___ A single RNA polymerase transcribes genes that encode mRNAs,tRNAs,and rRNA.
___ Transcription of mRNA is blocked by $\alpha$-amanitin.
___ Sigma ($\sigma$)subunit detaches from RNA polymerase shortly after transcription has initiated.
___ The 5' end of the mature mRNA begins with a triphosphate.
___ The primary mRNA transcript is inactive.
___ Termination of transcription requires the protein $\rho$ factor.

Accepted Answer

E and P
P

Question 9

Beginning with the primary transcript containing a tRNA sequence,describe the steps in the formation of a mature tRNA molecule in E.coli.

Accepted Answer

Short sequences at the 5' and 3' ends of

Question 10

What is a telomere? Describe the key features of its structure.What is unusual about the structure and/or mechanism of action of telomerase?

Accepted Answer

Telomeres are specialized structures at

Question 11

Which of the following is not a characteristic of the $\rho$-terminator in E.coli?

Accepted Answer

A) The $\rho$-terminator has an ATP-dependent RNA-DNA helicase activity. 
B) The $\rho$-terminator migrates in the 3'-5' direction along RNA. 
C) The $\rho$-terminator causes RNA polymerase release at a CA-rich sequence near the end of the transcript. 
D) ATP is hydrolyzed by the $\rho$-terminator during the termination process. 
E) All of the above are characteristics of the $\rho$-terminator. 
A) The $\rho$-terminator has an ATP-dependent RNA-DNA helicase activity. 
B) The $\rho$-terminator migrates in the 3'-5' direction along RNA. 
C) The $\rho$-terminator causes RNA polymerase release at a CA-rich sequence near the end of the transcript. 
D) ATP is hydrolyzed by the $\rho$-terminator during the termination process. 
E) All of the above are characteristics of the $\rho$-terminator.

Question 12

AZT (3'-azido-2',3'-dideoxythymidine),used to treat HIV infection,acts in HIV-infected cells by:

Accepted Answer

A) blocking ATP production. 
B) blocking deoxynucleotide synthesis. 
C) inhibiting reverse transcriptase. 
D) inhibiting RNA polymerase II. 
E) inhibiting RNA processing. 
A) blocking ATP production. 
B) blocking deoxynucleotide synthesis. 
C) inhibiting reverse transcriptase. 
D) inhibiting RNA polymerase II. 
E) inhibiting RNA processing.

Question 13

Which one of the following is not true of the mRNA for calcitonin?

Accepted Answer

A) Exons are used for polypeptide synthesis. 
B) Introns are complementary to their adjacent exons and will form hybrids with them. 
C) The mature mRNA is substantially shorter than the corresponding region on the DNA. 
D) The mRNA is originally synthesized in the nucleus,but ends up in the cytoplasm. 
E) The splicing that yields a mature mRNA occurs at very specific sites in the RNA primary transcript. 
A) Exons are used for polypeptide synthesis. 
B) Introns are complementary to their adjacent exons and will form hybrids with them. 
C) The mature mRNA is substantially shorter than the corresponding region on the DNA. 
D) The mRNA is originally synthesized in the nucleus,but ends up in the cytoplasm. 
E) The splicing that yields a mature mRNA occurs at very specific sites in the RNA primary transcript.

Question 14

Which of the following is not involved in mRNA processing in vertebrates?

Accepted Answer

A) 30S pre-rRNA 
B) The nucleoleus 
C) Ribonucleases 
D) snoRNAs. 
E) snoRNPs 
A) 30S pre-rRNA 
B) The nucleoleus 
C) Ribonucleases 
D) snoRNAs. 
E) snoRNPs

Question 15

Differential RNA processing may result in:

Accepted Answer

A) a shift in the ratio of mRNA produced from two adjacent genes. 
B) attachment of the poly(
A) tail to the 5' end of an mRNA. 
C) inversion of certain exons in the final mRNA. 
D) the production of the same protein from two different genes. 
E) the production of two distinct proteins from a single gene. 
A) a shift in the ratio of mRNA produced from two adjacent genes. 
B) attachment of the poly(
A) tail to the 5' end of an mRNA. 
C) inversion of certain exons in the final mRNA. 
D) the production of the same protein from two different genes. 
E) the production of two distinct proteins from a single gene.

Question 16

Describe all of the known catalytic activities of reverse transcriptase.

Accepted Answer

Reverse transcriptase can (1)synthesize

Question 17

The reverse transcriptase of an animal RNA virus catalyzes:

Accepted Answer

A) degradation of the RNA strand in a DNA-RNA hybrid. 
B) insertion of the viral genome into a chromosome of the host (animal)cell. 
C) RNA formation in the 3' $\rightarrow$ 5' direction. 
D) RNA synthesis,but not DNA synthesis. 
E) synthesis of an antisense RNA transcript. 
A) degradation of the RNA strand in a DNA-RNA hybrid. 
B) insertion of the viral genome into a chromosome of the host (animal)cell. 
C) RNA formation in the 3' $\rightarrow$ 5' direction. 
D) RNA synthesis,but not DNA synthesis. 
E) synthesis of an antisense RNA transcript.

Question 18

The 5'-terminal cap structure of eukaryotic mRNAs is a(n):

Accepted Answer

A) 7-methylcytosine joined to the mRNA via a 2',3'-cyclic linkage. 
B) 7-methylguanosine joined to the mRNA via a 5' $\rightarrow$ 3' diphosphate linkage. 
C) 7-methylguanosine joined to the mRNA via a 5' $\rightarrow$ 5' triphosphate linkage. 
D) N6-methyladenosine joined to the mRNA via a 5' $\rightarrow$ 5' phosphodiester bond. 
E) O6-methylguanosine joined to the mRNA via a 5' $\rightarrow$ 5' triphosphate linkage. 
A) 7-methylcytosine joined to the mRNA via a 2',3'-cyclic linkage. 
B) 7-methylguanosine joined to the mRNA via a 5' $\rightarrow$ 3' diphosphate linkage. 
C) 7-methylguanosine joined to the mRNA via a 5' $\rightarrow$ 5' triphosphate linkage. 
D) N6-methyladenosine joined to the mRNA via a 5' $\rightarrow$ 5' phosphodiester bond. 
E) O6-methylguanosine joined to the mRNA via a 5' $\rightarrow$ 5' triphosphate linkage.

Question 19

Which one of the following statements about E.coli RNA polymerase (core enzyme)is false?

Accepted Answer

A) It can start new chains de novo or elongate old ones. 
B) It has no catalytic activity unless the sigma factor is bound. 
C) It uses nucleoside 5'-triphosphates as substrates. 
D) Its activity is blocked by rifampicin. 
E) Its RNA product will hybridize with the DNA template. 
A) It can start new chains de novo or elongate old ones. 
B) It has no catalytic activity unless the sigma factor is bound. 
C) It uses nucleoside 5'-triphosphates as substrates. 
D) Its activity is blocked by rifampicin. 
E) Its RNA product will hybridize with the DNA template.

Question 20

Why did the "RNA World" hypothesis have to await the discovery of ribozymes in order to become a widely attractive scenario?

Accepted Answer

The existence of ribozymes proved that s

Exam 26: Rna Metabolism

Which of the following statements about E.coli RNA polymerase is false?

Transfer RNAs have several bases in addition to the normal four found in RNA.How are these rare bases incorporated into the tRNA molecule?

Which of the following statements about E.coli RNA polymerase (core enzyme)is false?

Describe the function of polyadenylate polymerase and name two properties that distinguish it from normal cellular RNA polymerases.

Aptamers are:

Which of the following is (are)characteristic of ρ\rhoρ -independent termination of RNA transcription in E.coli?

Beginning with the primary transcript containing a tRNA sequence,describe the steps in the formation of a mature tRNA molecule in E.coli.

What is a telomere? Describe the key features of its structure.What is unusual about the structure and/or mechanism of action of telomerase?

Which of the following is not a characteristic of the ρ\rhoρ -terminator in E.coli?

AZT (3'-azido-2',3'-dideoxythymidine),used to treat HIV infection,acts in HIV-infected cells by:

Which one of the following is not true of the mRNA for calcitonin?

Which of the following is not involved in mRNA processing in vertebrates?

Differential RNA processing may result in:

Describe all of the known catalytic activities of reverse transcriptase.

The reverse transcriptase of an animal RNA virus catalyzes:

The 5'-terminal cap structure of eukaryotic mRNAs is a(n):

Which one of the following statements about E.coli RNA polymerase (core enzyme)is false?

Why did the "RNA World" hypothesis have to await the discovery of ribozymes in order to become a widely attractive scenario?

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

Which of the following is (are)characteristic of $\rho$ -independent termination of RNA transcription in E.coli?

Which of the following is not a characteristic of the $\rho$ -terminator in E.coli?