Final answer:
Non-coding RNA molecules (ncRNA) can affect cell activities without coding for new proteins. They do this through RNA interference (RNAi) and by regulating the stability, function, or turnover rate of mRNA or proteins through post-transcriptional modifications.
Step-by-step explanation:
Non-coding RNA (ncRNA) molecules can affect cell activities without coding for new proteins through various mechanisms. One of the main ways ncRNAs influence cell activities is through a process called RNA interference (RNAi), where they prevent the synthesis of specific proteins by binding to complementary messenger RNA (mRNA). This prevents the mRNA from guiding the synthesis of proteins.
Another way ncRNAs can affect cell activities is by regulating the stability, function, or turnover rate of mRNA or proteins. Post-transcriptional modifications of mRNA or proteins can alter their activity and overall impact on cell activities.