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BIOL 200 UBC MIDTERM 2026
LATEST QUESTIONS AND
ANSWERS| ACE YOUR GRADES.
Which direction is DNA read? synthesized? - correct answer -
read 3' to 5' and synthesized 5' to 3'
Which direction is mRNA read? - correct answer -5' to 3'
Describe the difference between prokaryotes and eukaryotes. -
correct answer -Prokaryotes:
-no introns
-initiation by sigma factor
-operons, one promoter
-no nucleus
-loose,smaller DNA
-no compartments
Eukaryotes:
-introns, splicing
-transcripts exit nucleus for translation
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-initiation by GTFs
-individual promoters
When does histone modification occur? - correct answer -post-
translation
How do DNA-binding proteins (transcriptional factors) recognize
the binding site on DNA? - correct answer -through non-covalent
interactions with the sides of base pairs in the major and minor
grooves of the molecule
What enzymes are required in transcription? - correct answer -
RNA polymerases, basal and general transcription factors,
ribonucleoside triphosphates
Describe the mechanism of transcription. - correct answer -
transcription factors bind to promoter and recruit RNA pol
(initiation), elongation, termination
Describe the tail of RNA pol. - correct answer -it binds
processing factors such as capping factors, polyadenylation
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factors and splicing factors that are transferred to act on the
mRNA when necessary
Describe how an intron is spliced out. - correct answer --three
necessary sequences in pre-mRNA at intron/exon junctions and
in the intron (branch site): GU at 5', AG at 3' and an A in the
branch site
-U1 snRNP binds to 5' splice site, U2 binds to branch
-U4,5,6 come and bind to intron
-5' splice site is cut and curls to bind to A in branch site
-U1,U4 leave and 3' site is cut, exons connected
-U5,U6,U2 dissociate and lariat is degraded
How does alternative splicing occur? - correct answer --
controlled by proteins that activate, repress, silence or enhance
splicing by binding on mRNA
-secondary structures of pre-mRNA can mask or bring together
certain acceptor/donor sites
Does a tRNA molecule recognize only one mRNA codon
sequence? - correct answer -no there are multiple codon
sequences for one amino acid
BIOL 200 UBC MIDTERM 2026
LATEST QUESTIONS AND
ANSWERS| ACE YOUR GRADES.
Which direction is DNA read? synthesized? - correct answer -
read 3' to 5' and synthesized 5' to 3'
Which direction is mRNA read? - correct answer -5' to 3'
Describe the difference between prokaryotes and eukaryotes. -
correct answer -Prokaryotes:
-no introns
-initiation by sigma factor
-operons, one promoter
-no nucleus
-loose,smaller DNA
-no compartments
Eukaryotes:
-introns, splicing
-transcripts exit nucleus for translation
, Page | 2
-initiation by GTFs
-individual promoters
When does histone modification occur? - correct answer -post-
translation
How do DNA-binding proteins (transcriptional factors) recognize
the binding site on DNA? - correct answer -through non-covalent
interactions with the sides of base pairs in the major and minor
grooves of the molecule
What enzymes are required in transcription? - correct answer -
RNA polymerases, basal and general transcription factors,
ribonucleoside triphosphates
Describe the mechanism of transcription. - correct answer -
transcription factors bind to promoter and recruit RNA pol
(initiation), elongation, termination
Describe the tail of RNA pol. - correct answer -it binds
processing factors such as capping factors, polyadenylation
, Page | 3
factors and splicing factors that are transferred to act on the
mRNA when necessary
Describe how an intron is spliced out. - correct answer --three
necessary sequences in pre-mRNA at intron/exon junctions and
in the intron (branch site): GU at 5', AG at 3' and an A in the
branch site
-U1 snRNP binds to 5' splice site, U2 binds to branch
-U4,5,6 come and bind to intron
-5' splice site is cut and curls to bind to A in branch site
-U1,U4 leave and 3' site is cut, exons connected
-U5,U6,U2 dissociate and lariat is degraded
How does alternative splicing occur? - correct answer --
controlled by proteins that activate, repress, silence or enhance
splicing by binding on mRNA
-secondary structures of pre-mRNA can mask or bring together
certain acceptor/donor sites
Does a tRNA molecule recognize only one mRNA codon
sequence? - correct answer -no there are multiple codon
sequences for one amino acid
