BGM1004/L11 Transcripts Flashcards
How are clustered genes often transcribed?
As a single molecule of mRNA
What is a polycistronic mRNA?
mRNA corresponding to multiple genes whose expression is controlled by a single promoter and terminator
What kind of genes are single transcription units?
Monocistronic
When is a poly A tail added to mRNA?
After transcription
How many attachment points do transcription promoters have?
1 or 2
What does a region upstream (5’) of a gene contain?
Nucleotide sequences for association of transcription factors
What enzyme do transcription factors recruit?
RNA polymerase
What are conserved sequences recognised by in prokaryotes?
Sigma factor
What is a holoenzyme made up of? (2)
RNA polymerase
Sigma factor
At which point does sigma factor recognise different sequences?
-35 & -10
What would a mutation to a single sigma factor affect?
Expression of the set of genes it regulates
What is a microarray?
DNA corresponding to each gene in the organism’s genome spotted onto a slide
How are introns removed from pre-mRNA transcript?
Splicing
What feature of introns and exons ensure they are spliced correctly?
Conserved sequences at boundaries
What would a mutation in the intron sequence affect?
Splicing
What would a mutation in the exon sequence affect?
Sequence of coded protein
What can alternative splicing create?
Multiple products from each gene
What is the difference of transcriptase in alternative splicing?
Can become much more complex than genome
What is the small ribosomal subunit responsible for?
Finding start of ORFs in mRNA and interpreting each codon
What does the large ribosomal subunit house?
Protein synthetic peptidyl transferase centre
What is the Shine-Dalgarno sequence?
A sequence of bases that define the start of an ORF
UAAGGAGGU(N)5-7AUG
What would the mutation of a Shine-Dalgarno sequence cause?
Reduced translation of ORF it is associated with
What does eukaryotic translation initiation depend on?
5’ CAP on mRNA
What causes binding of the large ribosomal subunit?
Kozak consensus
Why can’t translation catch up with transcription in eukaryotes?
Translation and transcription occur in different cellular compartments
What codon/amino acid does translation start on?
AUG/methionine
