Lecture 5 Flashcards
Which viral genome is synthesized by RNA Pol II?
Hepatitis Delta Virus genome RNA (HDV)
Which viral genome is synthesized by RNA pol III?
Adenovirus Type II VA-RNAs, Epstein Barr Virus EBER RNAs
How many base pairs are core promoter?
20-35
How many base pairs are local regulatory sequences?
1x10^2 - 5x10^2
How many base pairs are distant regulatory sequences?
1x10^2 - 10^4
What are the distant regulatory sequences independent of?
Position and orientation
What are the core promoter elements?
Initiator sequence and TATA sequence
What are the distant regulatory elements?
Enhancers, silencers
What consist of the promoter?
Core promoter elements and local regulatory sequences
What consist of the transcriptional control region?
Core promoter + Local and distant regulatory sequences
A property of co-activators
They do not bind DNA but can modulate transcription
What is the origin of transcriptional components for poxvirus?
Viral
What is the origin of transcriptional components for simple retroviruses?
Host
What is the origin of transcriptional components for complex retroviruses, papillomaviruses, polyomaviruses, and parvoviruses?
Host + One viral protein that regulates transcription
What is the origin of transcriptional components for bacteriophage T3 and T7?
Host + One viral protein that transcribes late genes
What is the origin of transcriptional components for bacteriophage T4, adenoviruses, and herpesviruses?
Host + Several viral proteins that act sequentially to stimulate transcription of particular set of viral genes
What happens in a transcriptional cascade?
Transcriptional units are activated in a fixed sequence
What do positive autoregulatory loops do?
Alter the rate of transcription initiation, viral proteins stimulate transcription
What do negative autoregulatory loops do?
Repress gene expression
What are some autoregulatory viral transcriptional activators?
HSV ICP4, SV40 T
What are some viral transcriptional activators that bind DNA?
ICP4, T, E2, and EBNA
What are some viral transcriptional activators that bind host proteins?
HSV VP16
What are some viral transcriptional activators that liberate host TAs?
E1A, E7, T
When is the capping enzyme added?
When the RNA pol II C terminal domain is phosphorylated (After incorporation of 20-30NT)
What sequence does the poly(A) addition site have?
AAUAAA
What is the sequence of the site next to the poly(A) addition site?
GU/U
What protein binds to the poly(A) addition site?
Cpsf
What protein binds to the GU/U site?
Cstf
What proteins bind between Cpsf and Cstf?
CfI and cfII
When does the cleavage of the mRNA occur?
After the addition of poly(A) polymerase alongside CfI and CfII
What protein is at the 5’P end of Cstf following cleavage?
CfII
What protein is at the 3’-OH end of Cpsf following cleavage?
Poly (A) polymerase + CfI
What protein is responsible for slow polyadenylation?
Poly(A) polymerase
What protein is responsible for rapid polyadenylation?
PabII
What happens to GU/U sequence after cleavage and dissociation of Cstf protein?
Degradation
When is ATP used in polyadenylation and cleavage?
During slow and rapid polyadenylation
How many A’s are added in polyadenylation
~200
How many transesterification reactions happen during splicing?
Two
What are the two kinds of splicing?
Constitutive and alternative
What are the methods of alternative splicing?
- Exon skipping
- Alternative 5’ splice site
- Alternative 3’ splice site
What are the roles of alternative splicing?
It adds value as:
It creates new functional genes.
Coding information of a small DNA genome is expanded.
Regulates gene expression.
