Rna Splicing / Protein Synthesis Regulation

RNA splicing is a process in which certain parts, called introns, of an RNA molecule are cut out to create a desired RNA strand made out of exons, the parts of the RNA molecule that remain and are expressed. As a pre-mRNA molecule is guided through a spliceosome, small nuclear ribonucleoprotiens (snRNPs) find the areas where the pre-mRNA’s introns should be cut out. Since the pre-mRNA can be clipped in many different ways through RNA splicing, the coding on the pre-mRNA (and future mRNA) strand can vary as well. This concept is called alternative RNA splicing. The different exons paired together can code for numerous amino acids, depending on the way the introns are removed, and if there are different amino acids produced during translation in the ribosome, then there will be unique proteins created, too. This allows there to be more types of proteins in an organism than types of genes in an organism’s genome.
Repressor proteins can influence the regulation of protein synthesis by binding to operators (the segments of DNA that act as switches to either allow or prohibit RNA polymerase to create mRNA strands) in an operon. Since repressors block transcription of genes, many mRNA strands that could’ve been made would not have been transcribed or later translated into amino acids to create proteins. In a repressible operon, the operon is always “on”, allowing RNA polymerase to freely make mRNA copies. To turn the operon “off”, a repressor (in correspondence with a corepressor) binds to the operon, blocking RNA polymerase. In an inducible operon, however, the operon is always “off” (blocking RNA polymerase), unless an inducer binds to the repressor, detaching it from the operon, allowing RNA polymerase through. The prevention or allowance of transcription through repressors binding to operons causes a change in what genes can be expressed and a change in what mRNA strands can be produced to create certain proteins. In other words, the abundance of corepressors or