  The physical evolution of low-mass protostars is relatively well-established,
however, there are many open questions on the chemical structure of protostars.
The chemical fingerprint generated in the early embedded phase of star
formation may be transmitted to the later stages of star, planet and comet
formation. The factors that influence the chemical fingerprint are then of
interest to study, and determine whether the chemical structure is inherited
from the parent cloud or product of the physical processes during star
formation. Results of observations and modelling of molecules that trace the
cold and warm extended structures of embedded protostars are briefly presented
here. Two multiple protostellar systems are studied, IRAS 16293-2422 and VLA
1623-2417, both located in $\rho$ Ophiuchus. We find that the physical
structure of the protostars, that is the disk(-like) strucutres, outflow cavity
and different luminosities, are important factors in determining the chemical
structure of these embedded protostars.
