Objectives After completion of this section,you should be able to 1.Understand RNA polymerase involved in transcription. 2.Describe the process of RNA transcription and post- transcriptional modifications. 4.Appreciate the types of introns and mechanism of splicing
Objectives After completion of this section, you should be able to : 1. Understand RNA polymerase involved in transcription. 2. Describe the process of RNA transcription and posttranscriptional modifications. 4. Appreciate the types of introns and mechanism of splicing
Central dogma replication transcription translation DNA RNA→ Protein RNA replication reverse transcription
Central dogma Protein replication DNA reverse transcription RNA transcription translation RNA replication
Outline of the section 1.Transcription system 2.Biosynthesis process of RNA 3.Post-transcriptional modifications
Outline of the section 1. Transcription system 2. Biosynthesis process of RNA 3. Post-transcriptional modifications
RNA transcription A reaction in which a template strand of DNA is utilized by specific RNA polymerase to generate one kind of RNA. Getting the message out! transcription DNA RNA
RNA transcription transcription A reaction in which a template strand of DNA is utilized by specific RNA polymerase to generate one kind of RNA. Getting the message out! DNA RNA
Types of RNAs RNA type size function Coding RNA: mRNA variable carrying information of protein sequence Non-coding RNA: Transfer-tRNA small carrying amino acid to growing polypeptide Ribosomal-rRNA variable major and active component of ribosome, most abundant RNA Small nuclear-snRNA small RNA processing Small nucleolar-snoRNA small RNA processing Small cytoplasm-scRNA small 7SL-RNA-component of SRP Micro-RNA 21-22nt gene regulation Small interference-siRNA 20-25nt gene regulation
Types of RNAs RNA type size function Coding RNA: mRNA variable carrying information of protein sequence Non-coding RNA: Transfer-tRNA small carrying amino acid to growing polypeptide Ribosomal-rRNA variable major and active component of ribosome, most abundant RNA Small nuclear-snRNA small RNA processing Small nucleolar-snoRNA small RNA processing Small cytoplasm-scRNA small 7SL-RNA- component of SRP Micro-RNA 21-22nt gene regulation Small interference-siRNA 20-25nt gene regulation
28S rRNA 18S rRNA 5 S,5.8S,tRNA Electrophoresis of total RNA from eukaryotes
Electrophoresis of total RNA from eukaryotes
Section1 Transcription system
Section1 Transcription system
Transcription system Substrates:NTP(ATP,UTP,GTP,CTP) Template:DNA Enzyme:RNA polymerase,RNA-pol Other protein factors
Transcription system Substrates: NTP (ATP, UTP, GTP, CTP) Template: DNA Enzyme: RNA polymerase, RNA-pol Other protein factors
S1.1 RNA polymerase-RNA pol a.RNA pol in prokaryote In prokaryotic (bacteria)all types of RNA are synthesized by only one species of RNA polymerase
§1.1 RNA polymerase- RNA pol In prokaryotic (bacteria) all types of RNA are synthesized by only one species of RNA polymerase. a. RNA pol in prokaryote
Subunits of RNA polymerase in prokaryote subunit gene MW number function rp0A40000 2 Binding upper promoter element and regulatory factors B rp0B155000 1 Polymerase activity B rp0C160000 Binding to DNA(nonspecifically) 0 rp0D32000-920001 Binding specific promoter regions 0 9000 Not known Synthesize RNA B Promoter recognization 670:common promoter 032 HSP promoter Transcription specificity Core enzyme Holoenzyme
subunit gene MW number function α rpo A 40000 2 Binding upper promoter element and regulatory factors β rpo B 155000 1 Polymerase activity β′ rpo C 160000 1 Binding to DNA(nonspecifically) σ rpo D 32000-92000 1 Binding specific promoter regions ω 9000 Not known Subunits of RNA polymerase in prokaryote Core enzyme Holoenzyme Synthesize RNA Transcription specificity Promoter recognization σ 70 : common promoter σ 32 : HSP promoter