5.3 - DNA transcription

gene expression

processes by which DNA specifies traits in an organism

transcription and translation

central dogma

DNA → RNA → protein

DNA self replicates

DNA

double stranded, uses thymine and deoxyribose sugar

RNA

single-stranded, uses uracil and ribose sugar

initiation (transcription)

RNA polymerase binds to promoter region of gene with help from transcription factors

elongation (transcription)

RNA polymerase uses the template strand of DNA to build the mRNA

termination (transcription)

when RNA polymerase reaches a termination sequence, transcription ends

RNA polymerase detaches, releasing newly made mRNA (primary transcript)

capping (post-transcription mods in eukaryotes)

a G-cap is added to the 5’ end for protection and help w translation

polyadenylation (post-transcription mods in eukaryotes)

a poly-A-tail (20-30 adenines) is added to the 3’ end for stability

splicing (post transcription mods in eukaryotes)

non-coding regions (introns) are removed

coding regions (exons) are spliced tg to form mRNA

mRNA

identical to the coding strand with uracil instead of thymine

sequence is complementary to template strand