Acetyl

In organic chemistry, acetyl (ethanoyl), is a functional group, the acyl of acetic acid, with chemical formula -COCH3.
Structure.
The acetyl group contains a methyl group bonded to a carbonyl with a lone electron left over. This electron forms a chemical bond to the rest ("R") of the molecule.
Use.
The acetyl group is part of some organic compounds such as acetylcholine and acetyl-CoA.