1|Page
BCHM 4360 EXAM 3 NEWEST 2025/2026 ACTUAL EXAM WITH
COMPLETE QUESTIONS AND CORRECT DETAILED ANSWERS (100%
VERIFIED ANSWERS) |ALREADY GRADED A+| ||PROFESSOR
VERIFIED||
Most introns do not contain genes and are excised and degraded.
Exceptions are - ANSWER-snoRNAs and certain miRNAs
Some introns are removed by proteins, some by RNPs, and some
excise themselves. All mechanisms use
______________________ reactions - ANSWER-
Transesterification
Introns are far more prevalent in _____________________ -
ANSWER-Eukaryotes
Introns allow for ____________________, where exons are
exchanged and reordered via recombination, allowing evolution of
different genes - ANSWER-Exon shuffling
Differential removal of introns gives different transcripts from the
_______________ gene - ANSWER-Same
,2|Page
The two exons on either side of an intron are joined in a
__________ step process - ANSWER-Two
The intron is first detached from ___________ then it reacts with
exon 2 - ANSWER-Exon 1
Most introns are removed by a complex called the
_________________, but some are self splicing - ANSWER-
Spliceosome
Both steps of exon splicing involve ___________________
reactions
A single phosphodiester bond is broken and replaced by another
phosphodiester bond of similar energy - ANSWER-
Transesterification
The ____________________ of the two bonds means that the
reaction does not require ATP and it is easily reversible
,3|Page
(transesterification reactions during exon splicing) - ANSWER-
Similar energy
This group of introns are found in bacteria, viruses,
microeukaryotes, and plants - ANSWER-Group I introns
Group I introns are ______________ nucleotides long -
ANSWER-120-450
Many but not all of this group of introns can excise themselves
from the primary transcript - ANSWER-Group I introns
In this group of introns, splice sites are determined by the 3D
structure of the intron and by recognition of a conserved G-U
wobble pair - ANSWER-Group I introns
(which group of introns)
, 4|Page
In the first transesterification, a free guanosine is the attacking
species that detaches the 5' end of the intron from exon 1
In the second reaction, the released end of exon 1 attacks the
intron-exon 2 junction, joining the two exons together - ANSWER-
Group I introns
This group of introns are in bacteria and organellar genes of
plants and fungi - ANSWER-Group II introns
This group of introns are 400-1000 nucleotides long - ANSWER-
Group II introns
(which group of introns)
2' OH of a specific A within the intron attacks the exon 1-intron
junction
Once released, the intron forms a branched lariat intermediate -
ANSWER-Group II introns
BCHM 4360 EXAM 3 NEWEST 2025/2026 ACTUAL EXAM WITH
COMPLETE QUESTIONS AND CORRECT DETAILED ANSWERS (100%
VERIFIED ANSWERS) |ALREADY GRADED A+| ||PROFESSOR
VERIFIED||
Most introns do not contain genes and are excised and degraded.
Exceptions are - ANSWER-snoRNAs and certain miRNAs
Some introns are removed by proteins, some by RNPs, and some
excise themselves. All mechanisms use
______________________ reactions - ANSWER-
Transesterification
Introns are far more prevalent in _____________________ -
ANSWER-Eukaryotes
Introns allow for ____________________, where exons are
exchanged and reordered via recombination, allowing evolution of
different genes - ANSWER-Exon shuffling
Differential removal of introns gives different transcripts from the
_______________ gene - ANSWER-Same
,2|Page
The two exons on either side of an intron are joined in a
__________ step process - ANSWER-Two
The intron is first detached from ___________ then it reacts with
exon 2 - ANSWER-Exon 1
Most introns are removed by a complex called the
_________________, but some are self splicing - ANSWER-
Spliceosome
Both steps of exon splicing involve ___________________
reactions
A single phosphodiester bond is broken and replaced by another
phosphodiester bond of similar energy - ANSWER-
Transesterification
The ____________________ of the two bonds means that the
reaction does not require ATP and it is easily reversible
,3|Page
(transesterification reactions during exon splicing) - ANSWER-
Similar energy
This group of introns are found in bacteria, viruses,
microeukaryotes, and plants - ANSWER-Group I introns
Group I introns are ______________ nucleotides long -
ANSWER-120-450
Many but not all of this group of introns can excise themselves
from the primary transcript - ANSWER-Group I introns
In this group of introns, splice sites are determined by the 3D
structure of the intron and by recognition of a conserved G-U
wobble pair - ANSWER-Group I introns
(which group of introns)
, 4|Page
In the first transesterification, a free guanosine is the attacking
species that detaches the 5' end of the intron from exon 1
In the second reaction, the released end of exon 1 attacks the
intron-exon 2 junction, joining the two exons together - ANSWER-
Group I introns
This group of introns are in bacteria and organellar genes of
plants and fungi - ANSWER-Group II introns
This group of introns are 400-1000 nucleotides long - ANSWER-
Group II introns
(which group of introns)
2' OH of a specific A within the intron attacks the exon 1-intron
junction
Once released, the intron forms a branched lariat intermediate -
ANSWER-Group II introns
