BLGY1232 Gene expression
Central Dogma
Replication is the process by which DNA is copied so each daughter cell contains the
same amount of genetic information
Transcription is the process of copying nucleic acid letters from DNA into the nucleic
acid letters of RNA
Translation is the process by which the RNA sequence is converted into protein
Reverse transcription is the process by which RNA can be copied into DNA and
happens in retrovirus reproduction and at the end of telomeres
In a bacteria, the processes are coupled as the DNA of the bacteria are attached to
the inner membrane and anything in the cytoplasm can access that DNA as there is
no compartmentation of the genetic material from the protein synthetic machinery
the DNA is copied to produce mRNA by RNA polymerase and as the new RNA
strand is extending the beginning of it – the 5’ end – is already dissociating from its
template DNA and becoming available to be translated by ribosomes in the cytosol
In eukaryotes, transcription and translation occur in different compartment as DNA
is in the nucleus so transcription takes place within the nucleus and then mRNA is
transported through pores to the cytosol where translation happens the
production of an exported and translatable mRNA is only the final stage of a complex
series of events that distinguish the gene expression pathway in eukaryotes
Transcriptional control;
Positive – how RNA polymerase is recruited to a specific gene to initiate
mRNA synthesis
Negative – how transcription of a specific gene may be repressed
Post-transcriptional control;
Processing of transcripts
Transport/sequestration of transcripts
Stability of transcripts
Translational control;
Recruitment of mRNA by ribosomes
Expression of an “eclectic” eukaryotic gene
Promoter – a regulatory sequence ‘upstream’ of the coding sequence: binding site
for RNA polymerase and other transcription factors
UAS – Upstream Activating Sequence – a DNA sequence in a promotor that binds a
transcription factor may include specific developmental regulatory sequences
Central Dogma
Replication is the process by which DNA is copied so each daughter cell contains the
same amount of genetic information
Transcription is the process of copying nucleic acid letters from DNA into the nucleic
acid letters of RNA
Translation is the process by which the RNA sequence is converted into protein
Reverse transcription is the process by which RNA can be copied into DNA and
happens in retrovirus reproduction and at the end of telomeres
In a bacteria, the processes are coupled as the DNA of the bacteria are attached to
the inner membrane and anything in the cytoplasm can access that DNA as there is
no compartmentation of the genetic material from the protein synthetic machinery
the DNA is copied to produce mRNA by RNA polymerase and as the new RNA
strand is extending the beginning of it – the 5’ end – is already dissociating from its
template DNA and becoming available to be translated by ribosomes in the cytosol
In eukaryotes, transcription and translation occur in different compartment as DNA
is in the nucleus so transcription takes place within the nucleus and then mRNA is
transported through pores to the cytosol where translation happens the
production of an exported and translatable mRNA is only the final stage of a complex
series of events that distinguish the gene expression pathway in eukaryotes
Transcriptional control;
Positive – how RNA polymerase is recruited to a specific gene to initiate
mRNA synthesis
Negative – how transcription of a specific gene may be repressed
Post-transcriptional control;
Processing of transcripts
Transport/sequestration of transcripts
Stability of transcripts
Translational control;
Recruitment of mRNA by ribosomes
Expression of an “eclectic” eukaryotic gene
Promoter – a regulatory sequence ‘upstream’ of the coding sequence: binding site
for RNA polymerase and other transcription factors
UAS – Upstream Activating Sequence – a DNA sequence in a promotor that binds a
transcription factor may include specific developmental regulatory sequences
