3.2 transcription - gene structure Flashcards
gene
single transcriptional unit
the DNA primary sequence of DNA that results in the production of an RNA transcript
typically contains the promoter, coding sequence and terminator, though it may include additional regulatory elements
what direction do RNA (& DNA) polymerases read genes and move along the DN?
read in the 3’ to 5’ direction on the template strand
move along the DNA in the 3’ to 5’ direction
convergent genes
if expressed at the same time, the RNA polymerase will move towards each other
divergent genes
if expressed at the same time, RNA polymerase will move away from each other
coding strand
opposite strand to the template (where polymerases are reading the gene) that is anti-parallel to it
RNA polymerase
enzyme that carries out the polymerization
how do nucleic acids grow
all nucleic acids are synthesized by addition of nucleotides to the 3’ end
○ They grow in a 5’-3’ direction
○ AKA 3’ direction
promoters
○ Regions of typically a few hundred base pairs where RNA polymerase and associated proteins bind to the DNA duplex
○ TATA box
In many eukaryotic and archaeal promoters, the promoter includes the sequence 5’-TATAAA-3’
Sigma factor
mediates promotor recognition, associates with RNA polymerase and facilitates its binding to specific promoters
○ Once transcription Is initiated, the sigma factor dissociates and the RNA polymerase continues transcription on its own
bacteria
General transcription factors
6 proteins that assemble at the promoter of a gene, required for transcription
eukaryotes
helps RNA polymerase attach to the promoter
Transcriptional activator protein
needed for transcritpion, binds to a specific DNA sequence AKA enhancer
○ Helps control when and in which cells transcripion of a gene will occur
