Saturated fatty acids containing up to 16 carbon atoms are assembled in
Mitochondria
Rough endoplasmic reticulum
Smooth endoplasmic reticulum
Cytoplasm
Cytoplasm

The end product of cytosolic fatty acid synthesis cycles is saturated 16-carbon palmitic acid.
Elongation of pre-existing fatty acid :-
(i) Microsomnal (endoplasmic reticulum) :- Elongation of palmitic acid (16-C) into longer chain fatty acids
(ii) Mitochondrial :- Elongation of short and medium chain fatty acids containing fewer than 16 carbon atoms