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Chapter 3
The Transfer of Genetic Information
---- From---- From totoDNADNA RNARNA
3.1 Overview
1. Procedures of Gene Expression
(1) Gene expression
(2) Steps
①
②
③
④
5’------ATTGCCTGAATGGTCCC----3’
5’------TAACGGACTTACCAGGG----3’
5’------AUUGCCUGAAUGGUCCC----3’
5’------UAACGGACUUACCAGGG----3’
coding strand, non-template strand, sense strand, plus strand……(+)
template strand, antisense strand, minus strand……(─)
sense RNA
antisense RNA
2. Coding Strand and Antisense Strand
3. Steps are required for the transcription:
(1) Initiation
(2) Elongation
(3) Termination
4. Main Components for Transcription
substrate
template
RNA polymerase 5’ → 3’
Core enzyme(α2ββ ω)
holoenzyme(α2ββ ω )
RNA pol in prokaryotes
RNA polymerases in Eukaryotes
3.2 Transcription in Prokaryotes
1. DNA Elements for Initiation of Transcription in Prokaryotes
(1) Promoter
(2) Structure of Promoter
-35 region, -10 region, INR (Inr)
2. Initiation of Transcription in Prokaryotes
3. Elongation and Termination of Transcription in Prokaryotes
ρ-independent termination (strong)
ρ-dependent termination (weak)
3.3 Transcription in Eukaryotes
1. DNA Elements for Initiation of Transcription in Eukaryotes
Cis-acting elements
TATA box, UPE, UAS…..
Trans-acting factor
TFs
2. Initiation of Transcription in Eukaryotes
PIC of RNA pol II t
ranscription
upstream control eleme
nt (UCE).
upstream binding factors (UBF)
PIC of RNA pol I tr
anscription
upstream control eleme
nt (UCE).
upstream binding factors (UBF)
PIC of RNA pol III tr
anscription
TFIIB-related factor, BRF
PIC of 5S rRNA trans
cription
Animation
1. Coding RNA and Non-coding RNA
Coding RNA - mRNA
Non-coding RNA (ncRNA) - any RNA
that is not translated into a protein.
3.4 RNA Processing
2. Types of RNA Processing
End modification
Splicing
Cutting events
Chemical modification
3. End-modification of pre-mRNA
5’-cap
3’-Poly(A) : Polyadenylate polymerase
4. RNA Splicing
pre-mRNA splicing tRNA-splicing Group I intron splicing Group II intron splicing
pre-mRNA
The mechanism of pre-mRNA splicing
snRNPs
spliceosome
U1snRNPs is released.
U4snRNPs is released.
Two transesterification reactions
Animation
tRNA splicing
Group I intron splicing
Group II intron splicing
Alternative Splicing
Cis SplicingTrans Splicing
mRNA Editing of Human Apolipoprotein - B
5. RNA Editing
3.5 Reverse transcription
What is a Ribozyme?
Sidney Altman
Th omas Cech
1989 Nobel Prize In Chemistry
3.6 Ribozymes
Mechanism of Ribozyme
- the hammerhead ribozyme (plant virus)
- the hairpin ribozyme (plan virus)
- hepatitis delta ribozyme (human virus)
- group I and group II intron ribozyme
- RNAse P (tRNA maturation)
Types of Ribozyme
Natural ribozymes:Peptidyl transferase 23S rRNA
RNase P
Group I and Group II introns
Leadzyme
Hairpin ribozyme
Hammerhead ribozyme HDV ribozyme Mammalian CPEB3 ribozyme VS ribozyme glmS ribozyme CoTC ribozyme
RNA World Hypothesis
What is the origin of life?
DNA?
RNA?
Summary
1. Regulatory elements of prokaryotes and eukaryotes
for RNA transcription
2. RNA polymerase of prokaryotes and eukaryotes
3. Procedures of RNA transcription
4. mRNA structure of prokaryotes and eukaryotes
5. Types of RNA processing
6. Types of RNA splicing and their mechanisms
7. RNA editing mechanism
8. Mechanism of reverse transcription
9. Ribozyme and silencing mechanism