Genetic engineering, illustration. Synthetic small-ribonucleic acid (sRNA) being injected (needle tip at upper right) into the cell cytoplasm as part of a process of genetic engineering. At far right, gene transcription is taking place. This injection method is used to manipulate gene expression, with the sRNA strands disrupting the normal processes. At left is the cell nucleus, with polypeptide chains (made using the instructions contained in the cell's genes) being exported into the cell's cytoplasm.