Mechanism of eukaryotic transcription
Learning outcomes:
1. Eukaryotic genes (reminder)
2. RNA polymerase
3. Mechanism of basal transcription
Basal transcription is the transcription of DNA into RNA
Features of eukaryotes
Difference between eukaryotes and prokaryotes / bacteriophage
Eukaryotes Prokaryotes and bacteriophage
Nucleus present Circular DNA
1.8 meters of DNA packages around
histones
Recap
Promotor
= region
of DNA
where
RNA
polymerase binds to initiate transcription
Startpoint = position on DNA corresponding to the first base incorporated into RNA (begins at +1)
Terminator = sequence of DNA that causes RNA polymerase to terminate transcription
Transcription unit = sequence between site of initiation and termination by RNA polymerase (may include
more than one gene)
Features of eukaryotes
Interrupted gene = gene in the coding sequence that is not continuous due to presence of introns
Exons = segment of DNA that is transcribed and retained in the mature RNA product
Introns = segment of DNA transcribed but later removed from transcript by splicing together the exon
sequences on either side of it
Mature transcript = a modified RNA transcript. Modification include removal of intron sequences and
alteration to the 5’ and 3’ ends.
, Eukaryotic RNA polymerases
Transcription in eukaryotes is more complicated as there are 3 RNA polymerase with distinct properties
Each 1 specifically dedicated to rRNA, mRNA, tRNA synthesis
Eukaryotic RNA polymerases require numerous transcription factors
Transcription factor = protein that controls the rate of transcription
Eukaryotic RNA polymerase requires factors to modify chromatin structure to allow RNA polymerase access
All 3 RNA polymerase are:
Located differentially
All nuclear
Transcribe a particular class of RNA- not the same in bacteria
Enzyme Location RNA product
RNA polymerase l Nucleolus Synthesises non-coding RNA
- Nucleolus = electron - Pre rRNA, which are called:
dense structure in the 1.8S
middle of the nuclei 2.8S
5.8S
- rRNA make the ribosome
RNA polymerase ll Nucleoplasm Synthesis pre-mRNA.
- Nucleoplasm = Synthesis some snRNA
cytoplasmic
nuclear equivalent
RNA polymerase lll Nucleoplasm Synthesise tRNA
Synthesise signal recognition particle
RNA polymerases are beasts
RNA polymerase l has 14 subunits
RNA polymerase ll has 12 subunits
RNA polymerase lll has 17 subunits
Learning outcomes:
1. Eukaryotic genes (reminder)
2. RNA polymerase
3. Mechanism of basal transcription
Basal transcription is the transcription of DNA into RNA
Features of eukaryotes
Difference between eukaryotes and prokaryotes / bacteriophage
Eukaryotes Prokaryotes and bacteriophage
Nucleus present Circular DNA
1.8 meters of DNA packages around
histones
Recap
Promotor
= region
of DNA
where
RNA
polymerase binds to initiate transcription
Startpoint = position on DNA corresponding to the first base incorporated into RNA (begins at +1)
Terminator = sequence of DNA that causes RNA polymerase to terminate transcription
Transcription unit = sequence between site of initiation and termination by RNA polymerase (may include
more than one gene)
Features of eukaryotes
Interrupted gene = gene in the coding sequence that is not continuous due to presence of introns
Exons = segment of DNA that is transcribed and retained in the mature RNA product
Introns = segment of DNA transcribed but later removed from transcript by splicing together the exon
sequences on either side of it
Mature transcript = a modified RNA transcript. Modification include removal of intron sequences and
alteration to the 5’ and 3’ ends.
, Eukaryotic RNA polymerases
Transcription in eukaryotes is more complicated as there are 3 RNA polymerase with distinct properties
Each 1 specifically dedicated to rRNA, mRNA, tRNA synthesis
Eukaryotic RNA polymerases require numerous transcription factors
Transcription factor = protein that controls the rate of transcription
Eukaryotic RNA polymerase requires factors to modify chromatin structure to allow RNA polymerase access
All 3 RNA polymerase are:
Located differentially
All nuclear
Transcribe a particular class of RNA- not the same in bacteria
Enzyme Location RNA product
RNA polymerase l Nucleolus Synthesises non-coding RNA
- Nucleolus = electron - Pre rRNA, which are called:
dense structure in the 1.8S
middle of the nuclei 2.8S
5.8S
- rRNA make the ribosome
RNA polymerase ll Nucleoplasm Synthesis pre-mRNA.
- Nucleoplasm = Synthesis some snRNA
cytoplasmic
nuclear equivalent
RNA polymerase lll Nucleoplasm Synthesise tRNA
Synthesise signal recognition particle
RNA polymerases are beasts
RNA polymerase l has 14 subunits
RNA polymerase ll has 12 subunits
RNA polymerase lll has 17 subunits
