Test Bank Chapter 3: Gene Expression (Transcription &
Translation) + Regulation of Gene Expression | 100% Verified
Q&A with Detailed Rationales | A+ Rated | 2026–2027
Guaranteed Pass
An Adult Male Is Diagnosed With A Typical Pneumonia. His Physician Prescribes Clarithromycin,
Which Is Specific For Prokaryotic Cells. Which Of The Following Best Explains The Mechanism Of
Prokaryotic Specificity?
(A) The Drug Binds To The 50S Ribosomal Subunit Of Bacteria And Inhibits F-Met-Trnai Binding
(B) The Drug Binds To The 30S Ribosomal Subunit Of Bacteria And Blocks Initiation Of Protein
Synthesis
(C) The Drug Binds To The 50S Ribosomal Subunit Of Bacteria And Blocks Translocation
(D) The Drug Binds To The 30S Ribosomal Subunit Of Bacteria And Blocks Peptide Bond
Formation
(E) The Drug Binds To Both Ribosomal Subunits And Prevents Bacterial Ribosome Assembly
CORRECT ANS>>C Clarithromycin (An Antibiotic In The Macrolide Family With Erythromycin And
Azithromycin) Is Specific For The Large Ribosomal Subunit Of Prokaryotes (It Will Not Bind To
Eukaryotic Ribosomes). When This Drug Binds To The Large Ribosomal Subunit, Translocation Of
The Ribosome (Movement Along The Mrna) Is Blocked, Which Blocks Overall Protein Synthesis.
Trna Binding Is Not Affected By Clarithromycin, Nor Is There A Blockage Of The Formation Of An
Initiation Complex. It Is The Large Subunit (50S) That Contains The Peptidyl Transferase Activity,
Which Is Also Not Blocked By This Agent.
Which One Of The Following Is True For A Double- Stranded DNA Molecule?
CORRECT ANS>>A On A Molar Basis, DNA Contains Equal Amounts Of Adenine And Thymine
And Of Guanine And Cytosine. Uracil Is Not Found In DNA. There Are 10 Base Pairs Per Turn Of
The Helix, And The Overall Charge On The Molecule Is Negative, Due To The Phosphates In The
Backbone (Each Phosphodiester Bond Contains One Negative Charge).
, A Bacterial Mutant Grows Normally At 32°C But At 42°C Accumulates Short Segments Of Newly
Synthesized DNA. Which One Of The Following Enzymes Is Most Likely To Be Defective At The
Nonpermissive Temperature (The Higher Temperature) In This Mutant?
(A) DNA Primase
(B) DNA Polymerase
(C) An Exonuclease
(D) An Unwinding Enzyme (Helicase)
(E) DNA Ligase
CORRECT ANS>>E The Short Segments Of The Newly Synthesized DNA That Accumulate At 42°C
Are Okazaki Fragments. They Are Usually Joined Together By DNA Ligase, Which Most Likely
Exhibits Reduced Activity At 42°C In This Mutant. If The Ligase Is Not Functioning, Okazaki
Fragments Would Not Be Joined During Replication, So The Cells Would Contain Short
Fragments Of The DNA. Endonucleases And Exonucleases Cleave DNA Strands In The Middle
And At The Ends, Respectively. They Do Not Join Fragments Together, Nor Does DNA
Polymerase. Unwinding Enzymes "Unzip" The Parental Strands, And If These Were Defective,
DNA Synthesis Most Likely Would Not Occur At The Nonpermissive Temperature, And Short
DNA Fragments Would Not Accumulate.
An RNA Produced From A Fragment Of DNA Has The Sequence Of AAUUGGCU. The Sequence Of
The Nontemplate Strand In The DNA That Gave Rise To This Sequence Is Which One Of The
Following?
(A) AGCCAATT
(B) AAUUGGCU
(C) AATTGGCT
(D) TTAACCGA
(E) UUAACCGA
CORRECT ANS>>D The Nontemplate Strand In The DNA Is The Same As The Coding Strand, And
Will Have The Same Sequence Of The RNA That Is Produced, Except That T Is In Place Of U. Both
The Nontemplate Strand And RNA Produced Will Be A Complementary Sequence To The
Template Strand. As All Sequences Are Written In The 5′ To 3′ Direction, Unless Otherwise
Translation) + Regulation of Gene Expression | 100% Verified
Q&A with Detailed Rationales | A+ Rated | 2026–2027
Guaranteed Pass
An Adult Male Is Diagnosed With A Typical Pneumonia. His Physician Prescribes Clarithromycin,
Which Is Specific For Prokaryotic Cells. Which Of The Following Best Explains The Mechanism Of
Prokaryotic Specificity?
(A) The Drug Binds To The 50S Ribosomal Subunit Of Bacteria And Inhibits F-Met-Trnai Binding
(B) The Drug Binds To The 30S Ribosomal Subunit Of Bacteria And Blocks Initiation Of Protein
Synthesis
(C) The Drug Binds To The 50S Ribosomal Subunit Of Bacteria And Blocks Translocation
(D) The Drug Binds To The 30S Ribosomal Subunit Of Bacteria And Blocks Peptide Bond
Formation
(E) The Drug Binds To Both Ribosomal Subunits And Prevents Bacterial Ribosome Assembly
CORRECT ANS>>C Clarithromycin (An Antibiotic In The Macrolide Family With Erythromycin And
Azithromycin) Is Specific For The Large Ribosomal Subunit Of Prokaryotes (It Will Not Bind To
Eukaryotic Ribosomes). When This Drug Binds To The Large Ribosomal Subunit, Translocation Of
The Ribosome (Movement Along The Mrna) Is Blocked, Which Blocks Overall Protein Synthesis.
Trna Binding Is Not Affected By Clarithromycin, Nor Is There A Blockage Of The Formation Of An
Initiation Complex. It Is The Large Subunit (50S) That Contains The Peptidyl Transferase Activity,
Which Is Also Not Blocked By This Agent.
Which One Of The Following Is True For A Double- Stranded DNA Molecule?
CORRECT ANS>>A On A Molar Basis, DNA Contains Equal Amounts Of Adenine And Thymine
And Of Guanine And Cytosine. Uracil Is Not Found In DNA. There Are 10 Base Pairs Per Turn Of
The Helix, And The Overall Charge On The Molecule Is Negative, Due To The Phosphates In The
Backbone (Each Phosphodiester Bond Contains One Negative Charge).
, A Bacterial Mutant Grows Normally At 32°C But At 42°C Accumulates Short Segments Of Newly
Synthesized DNA. Which One Of The Following Enzymes Is Most Likely To Be Defective At The
Nonpermissive Temperature (The Higher Temperature) In This Mutant?
(A) DNA Primase
(B) DNA Polymerase
(C) An Exonuclease
(D) An Unwinding Enzyme (Helicase)
(E) DNA Ligase
CORRECT ANS>>E The Short Segments Of The Newly Synthesized DNA That Accumulate At 42°C
Are Okazaki Fragments. They Are Usually Joined Together By DNA Ligase, Which Most Likely
Exhibits Reduced Activity At 42°C In This Mutant. If The Ligase Is Not Functioning, Okazaki
Fragments Would Not Be Joined During Replication, So The Cells Would Contain Short
Fragments Of The DNA. Endonucleases And Exonucleases Cleave DNA Strands In The Middle
And At The Ends, Respectively. They Do Not Join Fragments Together, Nor Does DNA
Polymerase. Unwinding Enzymes "Unzip" The Parental Strands, And If These Were Defective,
DNA Synthesis Most Likely Would Not Occur At The Nonpermissive Temperature, And Short
DNA Fragments Would Not Accumulate.
An RNA Produced From A Fragment Of DNA Has The Sequence Of AAUUGGCU. The Sequence Of
The Nontemplate Strand In The DNA That Gave Rise To This Sequence Is Which One Of The
Following?
(A) AGCCAATT
(B) AAUUGGCU
(C) AATTGGCT
(D) TTAACCGA
(E) UUAACCGA
CORRECT ANS>>D The Nontemplate Strand In The DNA Is The Same As The Coding Strand, And
Will Have The Same Sequence Of The RNA That Is Produced, Except That T Is In Place Of U. Both
The Nontemplate Strand And RNA Produced Will Be A Complementary Sequence To The
Template Strand. As All Sequences Are Written In The 5′ To 3′ Direction, Unless Otherwise
