Overview of Eukaryotic Gene Expression Flashcards
What is the primary purpose of gene control in multicellular organisms?
Ensure precise developmental programs so that the proper genes are expressed in the proper cells at the proper times.
Name the two scenarios where gene control takes place.
Embryologic development and cellular differentiation.
Transcription in eukaryotes takes place on DNA that is wrapped in ________.
Chromatin.
Chromatin needs to be open for two reasons. Name them.
For the gene to be activated and for transcription to proceed.
What is epigenetic regulation?
Chromatin-mediated regulation (entirely new mechanism compared to prokaryotes).
Describe heterochromatin.
- Regions of chromosome that are more intensely stained.
- DNA is more tightly packed.
- It is rich in repetitive DNA (transposons), centromeres, and telomeres.
- It is not accessible to transcriptional machinery.
- Inactive genes are found here.
Describe euchromatin.
- ‘Eu’ = True
- Lightly stained chromosome regions
- Active genes are found here
Describe euchromatin.
- ‘Eu’ = True.
- Lightly stained chromosome regions.
- Active genes are found here.
Where are inactive genes found?
Heterochromatin.
Where are active genes found?
Euchromatin.
What kind of RNA is transcribed by RNA polymerase I?
Pre-rRNA (28S, 18S, 5.8S rRNAs)
What is the function of Pre-rRNA?
Ribosome components and protein synthesis.
What are the four kinds of RNAs transcribed by RNA Polymerase II?
- mRNA
- snRNAs
- siRNAs
- miRNAs
What is the function of mRNA?
Encode proteins.
What is the function of snRNAs?
RNA splicing.
What is the function of siRNAs?
Chromatin-mediated repression and translation control.
What is the function of miRNAs?
Translation control.
What are the five kinds of RNA polymerase transcribed by RNA polymerase III?
- tRNAs
- 5S rRNA
- snRNA U6
- 7S RNA
- Other small stable RNAs
What is the function of tRNAs?
Protein synthesis.
What is the function of 5S rRNA?
Ribosome component and protein synthesis.
What is the function of snRNA U6?
RNA splicing.
What is the function of 7S RNA?
Signal recognition particle for insertion of polypeptides into the endoplasmic reticulum.
What is the function of ‘other small stable RNAs’?
Various functions, unknown for many.
How many polypeptides are found in RNA pol II?
12 (RPB1-RPB12)
True or false? Eukaryotic RNA polymerase share a very high level of homology with the yeast RNA pol II?
True.
The clamp domain in the polymerase ________ accommodates DNA and then is closed by _______.
RPB1, a bridge.
Where does the synthesized RNA exit through?
A “channel”.
What is unique about the RPB1 subunit of RNA polymerase II?
It contains a carboxy-terminal domain (CTD). This is not found in any other polymerase, prokaryotic or eukaryotic.
Key role in initiation, release, elongation, and processing of the synthesized RNA.
What is the role of the CTD (carboxy-terminal domain) found in RNA polymerase II of the RPB1 subunit?
Involved in many regulatory interactions and plays a key role in the initiation, release, elongation and processing of the synthesized mRNAs.
What is the amino acid sequence of the CTD? How many repeats exist regularly? In mammals?
Tyr-Ser-Pro-Thr-Ser-Pro-Ser. 26 repeats. In mammals it is 52 repeats. (The Sad Player Tried Some Pro Soccer).
TSPTSPS
What is the fate of the Ser residues in the CTD upon transition from initiation to elongation.
The Ser residues are phosphorylated.
True or False? The CTD is structured and can be analyzed by crystallography?
False.
List the four ways that RNA polymerase II transcribed genes are regulated?
- CONSERVED BASAL ELEMENTS (CORE PROMOTER SEQUENCES)
- Promoter proximal binding sites for transcriptional activators.
- Distal enhances or repressors.
- Chromatin structure.
Name the position of the Core Promoter Element ‘BRE’
-37 to -32
Name the position of the Core Promoter Element ‘TATA Box’
-31 to -26
Name the position of the Core Promoter Element ‘Inr’ (Initiator)
-2 to +4
Name the position of the Core Promoter Element ‘DPE’ (Downstream promoter element)
+28 to +32
At promoters regulated by TATA box and initiator transcription starts at a defined point. Which TGCA does it usually bind to?
A
Where is the TATA box prevalent in?
Highly transcribed genes.
Some genes contain an initiator but no TATA box. Are these initiators highly or poorly conserved?
Poorly
‘BRE’ is know as the TFII__ (A-H) Recognition Element
TFIIB
RNA polymerases must recognize the promoter and correctly INITIATE transcription at a very specific point, however, it cannot do this alone. What does it require the help from?
General POLII Transcription Factors (GTFs).
What do the GTFs assemble?
The preinitation complex over the core promoter sequences.
True or False? Protein kinases release the polymerase?
True
List the 2 types of RNA Pol I TFIs?
TFIA and TFIB (A,B)
List the 5 types of RNA Pol 2 TFIIs?
TFIIA, TFIIB, TFIID, TFIIE, TFIIH (A,B,D,E,H)
List the 2 types of RNA Pol 3 TFIIIs?
TFIIIB, TFIIIS (B,S)
