exam 2 (hw questions) Flashcards
Bacterial DNA associates with various proteins to form a structure called the:
nucleoid
Which of the following chromatin features would you expect to find in a region of heterochromatin?
- H3K9me3
- H3K27ac
- Low levels of DNA methylation
- Low nucleosome occupancy
H3K9me3
RNAPs catalyze the formation of what type of bond?
phosphodiester
Which of the following is NOT a mechanism by which ATP-dependent chromatin remodelers can expose specific DNA sequences wrapped into nucleosomes?
- Sliding of nucleosomes
- Targeting of histones for destruction
- Unwrapping of nucleosomal DNA
- Eviction of nucleosomes
targeting of histones for destruction
what regions of a mammalian genome would you expect to have a high level of DNA methylation?
transposable elements
Histones are uniquely able to form strong interactions with DNA due to what feature?
Their unusually high basic amino acid content
Which subunit of bacterial RNAP targets it to specific sets of promoters?
sigma
Polycomb silencing and Trithorax activation are chromatin regulatory processes that primarily act on what histone residue?
H3K27
Which of the following histones is not part of the core nucleosome octamer?
- H4
- H1
- H2A
- H3
H1
Bacterial RNAP is capable of denaturing DNA at promoters. It can thus be considered what type of enzyme?
helicase
Which component of the lac operon system encodes the lac repressor?
lacl
which eukaryotic RNAPs transcribes rRNA?
RNAP1
lacOc mutations only cause constitutive expression of lac mRNA when they are on the same strand as a normal copy of lacZ. this means that they are is of what formation?
cis-domainant
Most eukaryotic promoters do not have a TATA box and so rely on what general transcription factor to begin PIC assembly?
TFIID
Which module of Mediator is responsible for contacting RNAPII bound to promoters?
head
The attenuator hairpin in the trp leader mRNA is formed by the interaction of what two leader segments?
3 and 4
Which of the following elements would you not expect to find in a eukaryotic core promoter?
- Inr
- -10 box
- TATA box
- BRE
-10 box
When glucose is added to a lactose-containing bacterial culture medium, the transcription of lac mRNA is silenced via what mechanism?
catabolite repression
Eukaryotic TFIIH serves what function in the context of the PIC?
promoter DNA melting
The trp operon encodes five enzymes and is shut off in response to high levels of tryptophan in the cells’ growth medium. These enzymes therefore fall into what category?
repressible
what eukaryotic transcription-related proteins is equivalent to bacterial GreA/GreB in the rescue of stalled RNAPs?
TFIIS
RNA editing can recode an “A” base in mRNA to what nonstandard base?
Inosine
Which of the following eukaryotic transcription-related proteins is NOT involved in the regulation of RNAPII pausing?
- TFIID
- NELF
- DSIF
- p-TEFb
TFIID
What feature of eukaryotic mRNAs can be used to purify them from bulk cellular RNA?
Poly(A) tail
Which histone modifications or variants would you expect to find primarily in the bodies of active genes?
H3K36me3
RNAPII transcription termination is coupled to what stage of RNA processing?
Cleavage and polyadenylation
Transcriptional activators bound to enhancers are contacted by what module of the Mediator complex?
tail
Which of the following is NOT a function of EUKARYOTIC mRNA polyadenylation?
- Nuclear export of mRNAs
- Destabilization of mRNAs -Recruitment of translation-related proteins to mRNAs
- Stabilization of mRNAs
-Destabilization of mRNAs
which organism has the longest intron
human
Which of the following biological phenomena we discussed was not discovered in a virus?
- Split genes
- Gene regulation by enhancers
- DNA methylation
- All of these were first described in viruses.
DNA methylation
Eukaryotic mRNAs can be isolated from total cellular RNA due to the presence of what sequence feature?
poly(A)-tail
Circular bacterial chromosomes interact with proteins to form a condensed structure known as the:
nucleoid
Which module of the Mediator complex is responsible for interaction with the promoter-bound general transcription machinery?
head
Which of the following is a false statement regarding mRNA capping?
- The cap is placed at the 5’ end of the pre-mRNA
- The cap enhances degradation of mRNAs by exonucleases
- Most mRNAs are capped
- Capping occurs co-transcriptionally
The cap enhances degradation of mRNAs by exonucleases
The complete, catalytically competent form of an enzyme is referred to as a(n):
holoenzyme
The eviction of HP1 and TFIID from chromosomes during mitosis is mediated by the interplay between what two types of histone modification?
methylation and phosphorylation
What is the function of lacO within the lacoperon?
it serves as bonding site for the lac repressor
Which of the following chromatin features would you notexpect to find at a heterochromaticregion?
- High levels of histone acetylation
- high levels of DNA methylation
- H3K9me3
- sensely packed nucleosomes
High levels of histone acetylation
RNA editing recodes A to which nonstandard base?
inosine
While bacterial RNAP contains the helicase activity necessary to melt promoter DNA, eukaryotic RNAPII requires some help. What general transcription factor performs this function?
TFIIH
hnRNA was an early term for what type of RNA
unprocessed mRNA
RNAP accumulates enough energy to transition from abortive initiation to productive elongation through what mechanism?
scrunching
What is the correct order of the RNA processing events listed below?
capping, cleavage, polyadenylation
what amino acid can not be phosphorylated by a kinase
cysteine
Which of the following elements is not involved in bacterial intrinsic transcription termination?
- stem loop
- rut site
- U-rich region
- all of these participate
rut site
Operons generate single mRNAs containing multiple protein-coding sequences. What is the generally accepted term for this type of mRNA?
polycistronic
telomeres are bound by what specialized eukaryotic protein complex
shelterin
the eukaryotic Xrn2 protein is involved in what step of mRNA processing?
termination
The enzymes encoded by the lac operon are turned on in response to a specific stimulus –the addition of lactose to the bacterial culture medium. These enzymes are thus of what class?
inducible
Bridging between eukaryotic enhancers and promoters is often achieved by what protein complex?
mediator