Title: Transcription
1Transcription
2Transcription
- ????????????????????????? (genetic information)
- ??? DNA (double-stranded) ?????????????????
RNA (single-stranded - ????????
- ??????????????????? (copy) RNA ??? gene
- ????????????????? RNA Synthesis
3Link ??????? Transcription Translation
4?????? Transcription
- 1. Factors ??? transcription
- 2. Direction ??? transcription
- 3. Mechanism ??? transcription
- 4. Control ??? transcription ?? Prokaryotic cells
- 5. Control ??? transcription ?? Eukaryotic cells
- 6. Mechanism ??? RNA splicing
- 7. Reverse transcription
5Factors ??????? Transcription
- 1. DNA template
- 2. RNA polymerase
- 3. Promoter
- 4. Terminator
61. DNA template
- ???????? 1 strand ???????? Template strand
- Strand ??????? ???????? Nontemplate strand
- RNA ???????? nontemplate ?????? U ??? T
- ???? mRNA ?????????? Sense strand ???? base
?????? nontemplate strand - ??????????? base ??? strand ?????????????????
base ??? gene
7Template and Nontemplate strands
8???????????? DNA Template ?????? Transcription
- Gene ????? DNA ???????? transcribed ?????? 3
???????????????????? - promoter...structural gene.terminator
9- Promoter
- ???? sequence ??????? DNA ????????? RNA
polymerase ?????????????????????? RNA - promoter ???????? startpoint ( 1) ???
structural gene ???????????????? nucleotide ???
promoter ???? ?? (-) - Terminator sequence
- ???? sequence ??????? DNA ?????????????? gene
?????????? Transcription
102. RNA polymerase
- ?????????????????????????????????
?????????????????????? Holoenzyme - ?????????? 2 components ???? ???
- Sigma (s) factor ?????? ???????? transcription
???????????????? - Core polymerase ??????????????? DNA template
?????? RNA nucleotides ??????????????????
transcription
11- RNA polymerase ?? 5 subunits ???
- - 1 s (Sigma) subunit
- - 2 a (Alpha) subunits
- - 2 b (Beta) subunits
12- RNA polymerase ?????????????????? proofreading
- ?????????????? nucleotides ???????????????????
?? - ?????? proofreading ???????? ????? RNA
?????????? - ??? ??????????? copies ???????????????????
133. Promoter
- ???? regulatory sequence ?? DNA ??????? binding
site ??? RNA polymerase ????? start transcription
- ???? signal ?????? initiation ??????????? DNA
strand ??????? transcribed - Transcription ????????????????????????????????????
?????????? promoter ??????????? RNA polymerase
??????????????
14Promoter ??????????????? RNA Polymerase Closed
promoter ???? weak promoterOpened promoter ????
strong promoter
154. Terminator
- ???? sequence ??? signal ???? transcription
- Terminator site ???? inverted repeat sequence ??
DNA template ??? ?? RNA ??????????? - ?? DNA form ????????????? (Cruciform structure)
- ?? RNA form ???? Stem-loop structure ???? base
??????????????? transcribed
16Terminator sequences?? DNA ????? RNA
17- Terminator ????????????? protein
???????????????????? transcription ???? rho (r)
???? NusA protein - RNA polymerase ?? terminator site ???
- ????? RNA polymerase ??????? DNA template
- ???? transcription ???????????????????
protein ????? - RNA polymerase ?? termination site ??????????
protein ????? ????????? transcription
18Direction ??? Transcription
- RNA ???????????????????
- ??? 5 ---gt 3
- ??? nucleotides ??????????????????????????????
3 ??? nucleotides ?????????????
19- ???????????????????? RNA polymerase
- ?????? ?????????? DNA ?????? Promoter
??????????? start point - DNA template ????????????????
- (unwind) ?????????????
- ????????????????????? (rewind)
- ?????? RNA polymerase ?????????
20- Mechanism ??? Transcription
- 1. Initiation
- 2. Elongation
- 3. Termination
211. Initiation of Transcription
- ??????? Promoter ??? RNA polymerase
- 1.1 Promoter
- ???? sequences ???? start point ????????????
upstream ?? (-) 1 ??????????????????? - Start point ?? structural gene ????????????
downstream ??? () 1 ?????????????????????????????
???
22- 1.2 RNA polymerase
- Holoenzyme ??????????????? promoter ????????
- Closed promoter
- s factor ??????????? promoter ????????? core
enzyme - ????? promoter ???????????????????
- Core enzyme ??? DNA ??????? Opened promoter
????????????????????? s factor ??????? start
point - Core enzyme ??? RNA nucleotide ????????? start
point - ????????????????? s factor ???????????? promoter
23Initiation of transcription
242. Elongation of Transcription
- Core ??? RNA polymerase ???????????? RNA
nucleotides ??????? 3 - OH ????????????
nucleotide ????????????? ??? ????????????????
?????? RNA ????????? 5 ---gt 3 - RNA ??? synthesis ??????????? complementary
??????? DNA template - ???? RNA ??????? synthesis ???????????????????????
template ??? template ???????????????? DNA
duplex
25Elongation of transcription?????????? core
enzyme ??? holoenzyme RNA polymerase
?????????????????????? RNA ?????
26Termination of Transcription
- RNA polymerase ?????????? terminator ??????
transcription - Terminator ?? 2 types ???
- 1) Rho - dependent terminator
- 2) Rho - independent terminator
- Terminator ???? 2 types ???????????? ??
- inverted repeat sequence ?? DNA ??? RNA
27- 1) Rho-dependent terminator
- Rho r ?????? RNA ???
- ?????????? ???? RNA ?????
- ??? RNA polymerase ???
- terminator
- ????? RNA polymerase ????
- ???? terminator ??????
- ???? transcription
- ???????? ? ????????????
28- 2) Rho-independent terminator
- ???? transcription
- ???????? rho protein
- ??? Terminator
- ??????? DNA ??
- base A ???
- ??? ?? RNA ??
- base U ???
- ???? stem-loop ????????????????? A-U base
pairs ??? - ??????? ??? stable ???? ????????? RNA ???
- RNA polymerase ?????????? DNA
???????transcription
29RNA Script
30RNA Script
- RNA ??? transcribed ?????????????? gene ????
????? RNA polymerase ???????????? gene ???????
?????? promoter - RNA script ????????????? (processing)
???????????????? - 1. 5 leader segment ????????????? start point
- 2. Protein-coding sequence ??? gene
- 3. 3 trailer segment ??????? terminator
31(No Transcript)
32Transcriptional Control in Prokaryote