Transcription

central dogma of biology

DNA (transcribed) → mRNA (translated) → polypeptide chain (folded) → protein

what is a gene?

region of DNA that codes for a specific RNA sequence

All genes have…

transcribed regions (turned into mRNA) and promoter regions (control transcription)

eukaryotic genes have…

exons (translated into proteins) and introns (spliced out, regulate gene expression)

prokaryotic genes…

do NOT have introns and some different related genes share the same promoter region

promoter region has…

binding sites (short, specific, recognisable, sequences of DNA) for RNA pol and TF

Process of transcription with activator transcription factors

activator TF bind to promoter → RNA pol bind to activators → activators move DNA to place RNA pol in binding site on promoter → RNA pol makes mRNA

how do repressors prevent transcription?

prevent physical connection between activator-RNA pol complex and promoter binding site, therefore preventing

Transcription factors and transcriptional control

multiple Tf need to be working together for efficient transcription
different quantities of TF can be used to control how many proteins are made

importance of transcriptional control (4)

TF control if/how much a gene is transcribed
different cells need different types/amounts of proteins
cells need different amounts of proteins at different times
receptors/signal transduction alter gene expression

alternative splicing

exons/parts of exons spliced out → different gene → different protein (short and long forms)

uses of alternative splicing

modifying proteins for use in different cells (e.g. heart, brain, muscle)