Final answer:
siRNAs increase mRNA degradation and decrease protein production. Alternative gene splicing increases the flexibility of gene expression. Phosphorylation levels of eIF-2 in translation initiation can inhibit protein synthesis.
Step-by-step explanation:
When siRNAs are present, they play a role in a process called RNA interference (RNAi), which leads to the degradation of mRNA. The presence of siRNAs causes the mRNA to be recognized as a target and degraded. This process increases the rate of mRNA degradation and consequently decreases the rate of protein production, because there is less mRNA template available for translation. Similarly, the binding of RNA binding proteins and mutations in the 5'UTR affect RNA stability and protein synthesis. Moreover, alternative gene splicing leads to an increase in the flexibility of gene expression since it allows for different mRNA variants leading to the production of different proteins from the same gene. Lastly, changes in components of the translation initiation complex, such as phosphorylation levels of eIF-2 in neurodegenerative diseases, can impact the rate of translation, often inhibiting it.