©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
MCB*2050 Midterm Prep Exam
Questions and Answers 100% Solved
RNA polymerase I - ✔✔- in nucleus of eukaryotic cells
- transcribes Pre-rRNA (28S, 18S, 5.8S rRNAs)
- make ribosome components and synthesize proteins
RNA polymerase II - ✔✔- in nucleus of eukaryotic cells
- transcribes mRNA,
snRNAs, siRNAs, and miRNAs
- encodes protein, RNA splicing, chromatin-mediated repression, and
translation cotrol
mRNA - ✔✔- messenger RNA
- transcribed by RNA polymerase II
- encodes protein
snRNAs - ✔✔- transcribed by RNA polymerase II
- small nuclear RNA
- RNA splicing
, ©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
siRNAs - ✔✔- transcribed by RNA polymerase II
- small interfering RNAs
- chromatin-mediated repression and translation control
miRNAs - ✔✔- transcribed by RNA polymerase II
- micro-interfering RNAs
- translation control
RNA polymerase III - ✔✔- in nucleus of eukaryotic cells
- transcribes tRNAs, 55 rRNA, snRNA U6, 7S RNA, and other small stable
RNAs
- they encode for proteins, form a ribosome component, perform RNA
splicing, create a signal recognition particle for insertion of polypeptides
into the endoplasmic reticulum, and other functions
tRNAs - ✔✔- transcribed by RNA polymerase III
- transfer RNA
- synthesize proteins
5S rRNAs - ✔✔- transcribed by RNA polymerase III
- the ribosome component
- synthesize proteins
, ©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
snRNA U6 - ✔✔- transcribed by RNA polymerase III
- splice proteins
7S RNAs - ✔✔- transcribed by RNA polymerase III
- signal recognition particle for insertion of polypeptides into the
endoplasmic reticulum
Control of gene expression in bacteria - ✔✔· Prokaryote gene
expression is regulated primarily by mechanisms that control transcription
· In prokaryotes one enzyme, RNA polymerase, transcribes all genes
· A group of proteins called sigma-factors recognize promotor elements (-
10, -35) and load RNA polymerase at the start site
· An operon is a group of genes that are all transcribed together with one
common promoter, so either all of the genes are transcribed or none of the
genes are transcribed (e.g. the lac operon)
· It is regulated by activator proteins (CAP, Catabolite Activator Protein)
that bind next to a promoter and recruit RNA polymerase
· Bacterial gene expression is regulated by transcriptional activators and
repressors
sigma-factors - ✔✔- recognize promotor elements (-35, -10) and load
RNA polymerase at the start site
, ©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
lac operon in bacteria - ✔✔- lac operon is a regulated promoter
- it is regulated by catabolite activator proteins (CAP) that bind next to a
promoter to recruit RNA polymerase
- it is repressed by the lac repressor which binds downstream of the
transcription initiation site
lac operon (- lactose, + glucose) - ✔✔- glucose is the preferred source of
energy so when it is present, there are low levels of cyclic AMP (cAMP)
and the lac repressor is bound downstream of the promoter site
- this inhibits the binding of the polymerase
lac operon (+ lactose, +glucose) - ✔✔- the lac repressor is activated in
the presence of lactose
- the 4 binding sites of the lac repressor are each bound by lactose
- this releases the lac repressor from blocking the transcriptional initiation
site
- transcriptional rate is low because there is still a presence of glucose and
therefore, the cAMP isn't bound
- glucose is still being metabolized
MCB*2050 Midterm Prep Exam
Questions and Answers 100% Solved
RNA polymerase I - ✔✔- in nucleus of eukaryotic cells
- transcribes Pre-rRNA (28S, 18S, 5.8S rRNAs)
- make ribosome components and synthesize proteins
RNA polymerase II - ✔✔- in nucleus of eukaryotic cells
- transcribes mRNA,
snRNAs, siRNAs, and miRNAs
- encodes protein, RNA splicing, chromatin-mediated repression, and
translation cotrol
mRNA - ✔✔- messenger RNA
- transcribed by RNA polymerase II
- encodes protein
snRNAs - ✔✔- transcribed by RNA polymerase II
- small nuclear RNA
- RNA splicing
, ©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
siRNAs - ✔✔- transcribed by RNA polymerase II
- small interfering RNAs
- chromatin-mediated repression and translation control
miRNAs - ✔✔- transcribed by RNA polymerase II
- micro-interfering RNAs
- translation control
RNA polymerase III - ✔✔- in nucleus of eukaryotic cells
- transcribes tRNAs, 55 rRNA, snRNA U6, 7S RNA, and other small stable
RNAs
- they encode for proteins, form a ribosome component, perform RNA
splicing, create a signal recognition particle for insertion of polypeptides
into the endoplasmic reticulum, and other functions
tRNAs - ✔✔- transcribed by RNA polymerase III
- transfer RNA
- synthesize proteins
5S rRNAs - ✔✔- transcribed by RNA polymerase III
- the ribosome component
- synthesize proteins
, ©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
snRNA U6 - ✔✔- transcribed by RNA polymerase III
- splice proteins
7S RNAs - ✔✔- transcribed by RNA polymerase III
- signal recognition particle for insertion of polypeptides into the
endoplasmic reticulum
Control of gene expression in bacteria - ✔✔· Prokaryote gene
expression is regulated primarily by mechanisms that control transcription
· In prokaryotes one enzyme, RNA polymerase, transcribes all genes
· A group of proteins called sigma-factors recognize promotor elements (-
10, -35) and load RNA polymerase at the start site
· An operon is a group of genes that are all transcribed together with one
common promoter, so either all of the genes are transcribed or none of the
genes are transcribed (e.g. the lac operon)
· It is regulated by activator proteins (CAP, Catabolite Activator Protein)
that bind next to a promoter and recruit RNA polymerase
· Bacterial gene expression is regulated by transcriptional activators and
repressors
sigma-factors - ✔✔- recognize promotor elements (-35, -10) and load
RNA polymerase at the start site
, ©JOSHCLAY 2024/2025. YEAR PUBLISHED 2024.
lac operon in bacteria - ✔✔- lac operon is a regulated promoter
- it is regulated by catabolite activator proteins (CAP) that bind next to a
promoter to recruit RNA polymerase
- it is repressed by the lac repressor which binds downstream of the
transcription initiation site
lac operon (- lactose, + glucose) - ✔✔- glucose is the preferred source of
energy so when it is present, there are low levels of cyclic AMP (cAMP)
and the lac repressor is bound downstream of the promoter site
- this inhibits the binding of the polymerase
lac operon (+ lactose, +glucose) - ✔✔- the lac repressor is activated in
the presence of lactose
- the 4 binding sites of the lac repressor are each bound by lactose
- this releases the lac repressor from blocking the transcriptional initiation
site
- transcriptional rate is low because there is still a presence of glucose and
therefore, the cAMP isn't bound
- glucose is still being metabolized
