BCNM 4360 EXAM 3 LATEST FINAL
2026 WITH COMPLETE QUESTIONS
AND VERIFIED CORRECT ANSWERS
| ALREADY GRADED A+ |
GUARANTEED SUCCESS | BCNM 4360
ACTUAL EXAM III [BRAND NEW!!]
What are some characteristics of Group II introns? - ANSWER- Found in bacteria
and in organellar genes of plants and fungi
~400-1000 nucleotides long
Can also act as mobile genetic elements by reverse splicing, and they often have
open reading frames within the introns that assist splicing
What is the mechanism for intron removal for Group II introns? - ANSWER- The
2' OH of a specific A within the intron attacks the exon1-intron junction.
Once released, the intron forms a branched lariat intermediate.
What is a similarity between Group I and Group II introns? - ANSWER- The
splice sites are determined by the 3D structure of the intron
Eukaryotic genes often have introns, which can be very long (
of bases) and account for up to
% of a pre-mRNA. - ANSWER- several,
thousands, 90
,True or False: Most eukaryotic introns are not self-splicing, so splicing is mediated
by the spliceosome, which operates similar to that of Group I introns. - ANSWER-
False: Everything is correct except that the spliceosome operates similar to that of
Group II introns
What is the spliceosome made up of? - ANSWER- several small nuclear
ribonucleoproteins (snRNP)
What are some short sequence motifs that the spliceosome recognizes for splice
sites? - ANSWER- the 5' and 3' splice sites and a branch-point nucleotide within
the intron (like the A in Group II introns) and a polypyrimidine region before the 3'
splice site
Usually, introns have and at their ends. - ANSWER- GU, AG
What are the 5 steps of how the spliceosome works? - ANSWER- 1. The 5' splice
site is recognized by U1 and other sequences are bound by non-snRNPs.
2-3. The rest of the splicing apparatus binds, sometimes displacing other factors,
including the branch-point-binding protein (BPP).
2. The pre-mRNA rearranges, the first transesterification reaction occurs and the
lariat forms.
3. Other rearrangements then bring the two exons together for the second
transesterification.
What is the EJC? - ANSWER- exon junction complex, left at splice junctions after
splicing and marks the transcript as processed and interacts with export and
translation proteins
What is the difference between cis and trans splicing? - ANSWER- Cis splicing is
where exons in the same molecule are joined together.
,Trans splicing is unusual, and joins exons from different RNA molecules.
What is the primary purpose of the end modifications of eukaryotic RNAs
following transcription? - ANSWER- protection of mRNAs from nuclease
degradation and assisting with protein interactions
What are the 5' ends of mRNAs capped with? - ANSWER- 7-methylguanine
nucleotide via a 5'-5' triphosphate linkage
What is the 5' cap needed for? - ANSWER- efficient elongation and termination of
the transcript, for mRNA processing and export from the nucleus, and for directing
translation
What are the three steps for the addition of the 5' cap? - ANSWER- 1. An RNA 5'
triphosphate catalyzes removal of a phosphate from the 5' end
2. A guanyl transferase attaches a guanosine monophosphate (GMP) to the end in a
5'-5' triphosphate linkage
3. The guanine is methylated by a guanine-7-methyltransferase
The 3' end of most eukaryotic mRNAs have about adenosines added, known as
the poly(A) tail. - ANSWER- 200
, Polyadenylation at the site retains multiple regulatory sequences.
Polyadenylation at the site eliminates the regulatory sequences. -
ANSWER- distal, proximal
What are the steps for the addition of the poly(A) tail? - ANSWER- 1. Initial
cleavage after a CA that lies between a conserved AAUAAA hexamer and a U or
GU-rich region
2. After cleavage, ~200 adenosines are added by poly(A) polymerase
What is responsible for mediating mRNA processing? - ANSWER- The CTD of
the largest subunit of RNA Pol II, RBP1
is needed to allow RNA Pol II to continue transcription.
is needed for efficient transcription termination. - ANSWER- Capping,
polyadenylation
How does the CTD of RBP1 sequentially recruit the different processing
complexes? - ANSWER- 1. CTD becomes partially phosphorylated on
transcription initiation and recruits capping enzyme
2. Elongation leads to more phosphorylation of CTD, which recruits splicing
machinery
3. This also leads to recruitment of the cleavage and polyadenylation complex
True or False: Transcription, processing, and translation all occur in the nucleus. -
ANSWER- False: Transcription and processing occur in the nucleus, but
translation occurs in the cytoplasm so mature mRNAs must be exported from the
nucleus
2026 WITH COMPLETE QUESTIONS
AND VERIFIED CORRECT ANSWERS
| ALREADY GRADED A+ |
GUARANTEED SUCCESS | BCNM 4360
ACTUAL EXAM III [BRAND NEW!!]
What are some characteristics of Group II introns? - ANSWER- Found in bacteria
and in organellar genes of plants and fungi
~400-1000 nucleotides long
Can also act as mobile genetic elements by reverse splicing, and they often have
open reading frames within the introns that assist splicing
What is the mechanism for intron removal for Group II introns? - ANSWER- The
2' OH of a specific A within the intron attacks the exon1-intron junction.
Once released, the intron forms a branched lariat intermediate.
What is a similarity between Group I and Group II introns? - ANSWER- The
splice sites are determined by the 3D structure of the intron
Eukaryotic genes often have introns, which can be very long (
of bases) and account for up to
% of a pre-mRNA. - ANSWER- several,
thousands, 90
,True or False: Most eukaryotic introns are not self-splicing, so splicing is mediated
by the spliceosome, which operates similar to that of Group I introns. - ANSWER-
False: Everything is correct except that the spliceosome operates similar to that of
Group II introns
What is the spliceosome made up of? - ANSWER- several small nuclear
ribonucleoproteins (snRNP)
What are some short sequence motifs that the spliceosome recognizes for splice
sites? - ANSWER- the 5' and 3' splice sites and a branch-point nucleotide within
the intron (like the A in Group II introns) and a polypyrimidine region before the 3'
splice site
Usually, introns have and at their ends. - ANSWER- GU, AG
What are the 5 steps of how the spliceosome works? - ANSWER- 1. The 5' splice
site is recognized by U1 and other sequences are bound by non-snRNPs.
2-3. The rest of the splicing apparatus binds, sometimes displacing other factors,
including the branch-point-binding protein (BPP).
2. The pre-mRNA rearranges, the first transesterification reaction occurs and the
lariat forms.
3. Other rearrangements then bring the two exons together for the second
transesterification.
What is the EJC? - ANSWER- exon junction complex, left at splice junctions after
splicing and marks the transcript as processed and interacts with export and
translation proteins
What is the difference between cis and trans splicing? - ANSWER- Cis splicing is
where exons in the same molecule are joined together.
,Trans splicing is unusual, and joins exons from different RNA molecules.
What is the primary purpose of the end modifications of eukaryotic RNAs
following transcription? - ANSWER- protection of mRNAs from nuclease
degradation and assisting with protein interactions
What are the 5' ends of mRNAs capped with? - ANSWER- 7-methylguanine
nucleotide via a 5'-5' triphosphate linkage
What is the 5' cap needed for? - ANSWER- efficient elongation and termination of
the transcript, for mRNA processing and export from the nucleus, and for directing
translation
What are the three steps for the addition of the 5' cap? - ANSWER- 1. An RNA 5'
triphosphate catalyzes removal of a phosphate from the 5' end
2. A guanyl transferase attaches a guanosine monophosphate (GMP) to the end in a
5'-5' triphosphate linkage
3. The guanine is methylated by a guanine-7-methyltransferase
The 3' end of most eukaryotic mRNAs have about adenosines added, known as
the poly(A) tail. - ANSWER- 200
, Polyadenylation at the site retains multiple regulatory sequences.
Polyadenylation at the site eliminates the regulatory sequences. -
ANSWER- distal, proximal
What are the steps for the addition of the poly(A) tail? - ANSWER- 1. Initial
cleavage after a CA that lies between a conserved AAUAAA hexamer and a U or
GU-rich region
2. After cleavage, ~200 adenosines are added by poly(A) polymerase
What is responsible for mediating mRNA processing? - ANSWER- The CTD of
the largest subunit of RNA Pol II, RBP1
is needed to allow RNA Pol II to continue transcription.
is needed for efficient transcription termination. - ANSWER- Capping,
polyadenylation
How does the CTD of RBP1 sequentially recruit the different processing
complexes? - ANSWER- 1. CTD becomes partially phosphorylated on
transcription initiation and recruits capping enzyme
2. Elongation leads to more phosphorylation of CTD, which recruits splicing
machinery
3. This also leads to recruitment of the cleavage and polyadenylation complex
True or False: Transcription, processing, and translation all occur in the nucleus. -
ANSWER- False: Transcription and processing occur in the nucleus, but
translation occurs in the cytoplasm so mature mRNAs must be exported from the
nucleus
