the.com/subunit
A part that refuses to be the whole story, and rightly so.
means A distinct smaller component that joins others to build a larger structure or molecule.
from From Latin sub- (under, beneath) plus unit, itself from unus (one) — literally a lesser one stacked into something bigger.
Protein assemblyHemoglobin needs four subunits to carry oxygen.
Strength in numbersMany subunits form quaternary structure in biology.
Beyond biologyUsed in chemistry, engineering, and military organization.