Gene Regulation Summary (A-level 2nd Year)

Gene regulation (switched on/off) – post transcriptional + post translational


 Gene expression regulated at 2 major times =
1) during development (embryo to adult differentiated form)
2) at appropriate time once differentiation has occurred



POST – TRANSCRIPTIONAL GENE REGULATION
Prokaryotes – whole length of DNA is coding DNA: codes for proteins
Eukaryotes – most DNA is non – coding: doesn’t code for protein; interferes w coding DNA
(genes)
 Might not code for proteins but may code for tRNA, rRNA, siRNA’s
 Might be non-coding because section of DNA that is particular base sequence might
be promotor sequence/enzyme-binding sites on DNA
 Enzyme binding sites, such as restriction endonucleases (genetic engineering topic)
 (promotor is where the RNA polymerase binds for it to be able to start transcription,
if RNA polymerase binds at promotor, transcription takes place)


Small part of DNA is actually coded: codes for proteins which can be expressed (by
transcription + translation).


Introns- Non-coding DNA
Exons – coding DNA
Splicing- gets rid of introns
Intragenetic introns- within the gene




POST – TRANSCRIPTIONAL GEE REGULATION – SPLICING
Transcription translation
DNA-------------------------mRNA----------------Polypeptide------------------Active Protein