Outline the processes of RNA splicing and post-translational modification of
proteins
RNA Splicing
As mRNA is made up of coding and non coding regions (exons and introns), it
needs to be edited so that the intron sections can be removed for translation and
formation of the polypeptide can occur.
This removal of introns is done by spliceosomes which are large RNA-protein
complexes that cut out introns and splice together the exons. This is the
functional mRNA that is used for translation at the ribosomes.
Post-translational modification of proteins
Some introns code for various active RNA.
Examples include:
 Antisense RNA’s that are made on the complementary DNA strand
complementary to the coding strand and can intercept and bind to the
coding mRNA strand, preventing it from being translated into a protein
 MicroRNA’s are small RNA’s that interfere with and suppress mRNA’s
made by specific exons
 Riboswitches are RNA’s that code like mRNA for particular proteins
however they have a region which acts as a switch to turn protein
synthesis on or off in response to changes in the environment, eg.
Temperature change, or changes in concentration of vitamins, amino
acids. The switch changes shape so inhibits or promotes production of the
protein specific to it.