Small RNA molecules can transfer acquired physical and behavioral adaptations across generations without altering the underlying DNA sequence.
Genome and RNA — DNA holds the master instructions in every cell, while messenger RNA directs protein assembly and other non-coding RNAs regulate cellular activity .
Traditional biological barriers — Two biological concepts previously suggested acquired traits could not be inherited:
The Weismann barrier prevents physical changes in non-reproductive body cells from passing into sperm and egg cells .
Epigenetic reprogramming wipes away roughly 90% of acquired chemical tags during reproduction .
RNA interference — Double-stranded RNA generates small RNAs that destroy targeted messenger RNA, shutting down matching genes across the entire organism and passing into reproductive cells .
Inherited antiviral defense — Roundworms exposed to a virus transmit protective small RNAs to their offspring, keeping descendants resistant across generations even when offspring lack the machinery to make their own defense molecules
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