BCH 361 EXAM 5 QUESTIONS WITH VERIFIED
ANSWERS
Replication: Prokaryotic Initiation - Answers - - Initiated by protein DnaA: recognizes
replication origins
- DnaA binds to the replication origin, creating small bubble of denatured DNA
- DnaA recruits DnaB (helicase: separates strands by hydrolyzing ATP for energy) to
the replication origin untangle the DNA
- Single Stranded Binding Protein: prevents the strands from reannealing
Topoisomerase - Answers - Helps relax the strands during prokaryotic replication
initiation, and prevents them from reannealing
RNA Primase - Answers - Creates a complementary RNA (a primer) using DNA as the
template in replication initiation; adds DNA to the 3' end, requiring Mg^2+ to function
High Processivity - Answers - DNA polymerase can synthesize a long stretch of DNA
without detaching from the template; pol 3 has a sliding DNA clamp that wraps around
the newly formed double helix to prevent detachment (replication initiation)
Replication - Answers - both strands of the template are copied simultaneously by the
same complex
Replication Fork - Answers - site of active replication
Leading Strand - Answers - the new complementary strand continuously created, 5'->3'
Lagging Strand - Answers - the new complementary strand discontinuously created, 3'-
>5'
Okazaki Fragments - Answers - mixture of RNA primers and DNA primers that make up
the lagging strand
Ligase - Answers - connects fragments by phosphodiester bonds by hydrolyzing ATP
Telomeres/Telomerase - Answers - Extends the telomeres (6 nucleotide motif) using
RNA as the template to prevent chromosomes from becoming shortened through
replication, also known as reverse transcriptase
Where does prokaryotic activity occur? - Answers - The cytoplasm
, Where does eukaryotic activity occur? - Answers - Replication/Transcription are in the
nucleus, Translation is in the cytoplasm
3 classes of RNA - Answers - rRNA, mRNA, tRNA (snRNA)
RNA Polymerase Holoenzyme - Answers - Recognizes the promoter sequence, sigma
factor binds to DNA, core reads the DNA and produces RNA
Catalytic Core: 2 alphas, 1 beta, 1 beta', and omega
Sigma Factor
Transcription: Prokaryotic Promoter Sequence - Answers - -10 site: Pribnow Box,
TATAAT
-35 site: TTGACA
Template Strand - Answers - The DNA strand that provides the template for ordering
the sequence of nucleotides in an mRNA transcript, extends in the 5'-> 3' direction
without the need of a primer
Transcription: Prokaryotic Initiation - Answers - - holoenzyme binds to DNA, slides until
it finds a promoter
- separates DNA strands and initiates RNA polymerization
- sigma factor dissociates from RNA pol once elongation convenes to activate core
enzymes
Transcription: Protein Independent Termination - Answers - signal is coded for newly
made RNA; palindromic sequences form as a hairpin followed by U
Transcription: Protein Dependent Termination - Answers - A protein is needed to
remove RNA polymerase; protein rho recognizes the sequence in the transcript (lots of
C, no G)
Transcription: Regulation Lac Operon - Answers - Active in the presence of lactose
- operator: a sequence separating the promoter and cooding region
- Allactose binds to the repressor, preventing it from binding to the operator, promoting
transcription
- Absence of allactose causes the lac repressor to bind to the operator, preventing
transcription
Allactose - Answers - Inducer of the lac operon
Transcription: Regulation cAMP - Answers - - low glucose triggers cAMP production
- CAP enhances transcription
- cAMP binds to CAP
- cAMP-CAP binds to sequence close to lac operon promoter
- CAP recruits RNA pol, promoting transcription
ANSWERS
Replication: Prokaryotic Initiation - Answers - - Initiated by protein DnaA: recognizes
replication origins
- DnaA binds to the replication origin, creating small bubble of denatured DNA
- DnaA recruits DnaB (helicase: separates strands by hydrolyzing ATP for energy) to
the replication origin untangle the DNA
- Single Stranded Binding Protein: prevents the strands from reannealing
Topoisomerase - Answers - Helps relax the strands during prokaryotic replication
initiation, and prevents them from reannealing
RNA Primase - Answers - Creates a complementary RNA (a primer) using DNA as the
template in replication initiation; adds DNA to the 3' end, requiring Mg^2+ to function
High Processivity - Answers - DNA polymerase can synthesize a long stretch of DNA
without detaching from the template; pol 3 has a sliding DNA clamp that wraps around
the newly formed double helix to prevent detachment (replication initiation)
Replication - Answers - both strands of the template are copied simultaneously by the
same complex
Replication Fork - Answers - site of active replication
Leading Strand - Answers - the new complementary strand continuously created, 5'->3'
Lagging Strand - Answers - the new complementary strand discontinuously created, 3'-
>5'
Okazaki Fragments - Answers - mixture of RNA primers and DNA primers that make up
the lagging strand
Ligase - Answers - connects fragments by phosphodiester bonds by hydrolyzing ATP
Telomeres/Telomerase - Answers - Extends the telomeres (6 nucleotide motif) using
RNA as the template to prevent chromosomes from becoming shortened through
replication, also known as reverse transcriptase
Where does prokaryotic activity occur? - Answers - The cytoplasm
, Where does eukaryotic activity occur? - Answers - Replication/Transcription are in the
nucleus, Translation is in the cytoplasm
3 classes of RNA - Answers - rRNA, mRNA, tRNA (snRNA)
RNA Polymerase Holoenzyme - Answers - Recognizes the promoter sequence, sigma
factor binds to DNA, core reads the DNA and produces RNA
Catalytic Core: 2 alphas, 1 beta, 1 beta', and omega
Sigma Factor
Transcription: Prokaryotic Promoter Sequence - Answers - -10 site: Pribnow Box,
TATAAT
-35 site: TTGACA
Template Strand - Answers - The DNA strand that provides the template for ordering
the sequence of nucleotides in an mRNA transcript, extends in the 5'-> 3' direction
without the need of a primer
Transcription: Prokaryotic Initiation - Answers - - holoenzyme binds to DNA, slides until
it finds a promoter
- separates DNA strands and initiates RNA polymerization
- sigma factor dissociates from RNA pol once elongation convenes to activate core
enzymes
Transcription: Protein Independent Termination - Answers - signal is coded for newly
made RNA; palindromic sequences form as a hairpin followed by U
Transcription: Protein Dependent Termination - Answers - A protein is needed to
remove RNA polymerase; protein rho recognizes the sequence in the transcript (lots of
C, no G)
Transcription: Regulation Lac Operon - Answers - Active in the presence of lactose
- operator: a sequence separating the promoter and cooding region
- Allactose binds to the repressor, preventing it from binding to the operator, promoting
transcription
- Absence of allactose causes the lac repressor to bind to the operator, preventing
transcription
Allactose - Answers - Inducer of the lac operon
Transcription: Regulation cAMP - Answers - - low glucose triggers cAMP production
- CAP enhances transcription
- cAMP binds to CAP
- cAMP-CAP binds to sequence close to lac operon promoter
- CAP recruits RNA pol, promoting transcription
