CMB2001 Control of Eukaryotic Gene Expression Flashcards
What is Gene expression?
Process by which information in genes (DNA) is decoded into protein.
What is transcription?
Transfer of genetic information from dsDNA to ssRNA (mRNA)
Describe the process of initiation of transcription in prokaryotes
-σ70 combines interacts with RNA polymerase, working together to recognise promoter regions and initiate transcription, forming an open complex.
After how many bases does σ70 detach?
~10 bases
What are promoters?
Cis acting DNA regulatory element through which transcription is initiated and controlled.
What are the regions that make up Eukaryotic promoters?
-Regulatory region
-Core (basal) region
Which region of eukaryotic promoters are further upstream?
Regulatory region
Name some core (basal) promoter elements
-TATA box
-Initiator (Inr)
-MTE (Motif ten element)
-DPE (Downstream core promoter element)
-BRE (TFIIB Recognition element)
-CpG islands
Describe what occurs when CpG islands are methylated?
They are silenced (ie transcription is switched off)
What class of eukaryote contains CpG islands?
Mammalia
Do Eukaryotic promoters have all elements?
NO
What is the UAS found in promoter regions?
Upstream activating sequence, an activator binding site
What is the URS found in promoter regions?
Upstream repressing sequence, A repressor binding site
What are the two tools to identify promoter elements?
-Sequence comparison
-Reporter analysis
What does sequence comparison of promoters consist of?
-Lining up sequences with known consensus sequences
-Helps identify key characteristics eg TATA boxes
What is the limitation with sequence comparison of promoters?
Does not tell us function and mechanism
What does reporter analysis of promoters consist of?
-Attach a regulatory sequence to a reporter gene
-Using regulatory sequence in question to express a “reporter” gene which is easy to measure in terms of quantity of expression
Give examples of reporter genes
-GFP
-Luciferase
-LacZ (β-galactosidase)
Why is the quantity of reporter protein significant?
Provides a measure of gene expression
What can reporter analysis be used to identify?
-When a gene is expressed
-Where it is expressed
-What signals it responds to
-What factors and sequences control its expression
Name some major eukaryotic RNA polymerases
-RNA pol I
-RNA pol II
-RNA pol III
What is the target gene of RNA pol I?
rRNA
Where is RNA pol I located?
In the nucleolus
What is the target gene of RNA pol II?
-mRNA
-snRNAs
-miRNAs