Construct a musical composition following the given alphabetical structure and incorporating the specified motif.
X:1
L:1/8
M:4/4
K:G
['B2 cA', 'G4 dedc B<G G2 cBAG F<D D2']  
X:1
L:1/8
M:4/4
K:G
|: B2 cA B<G G2 | cBAG F<D D2 | B2 cA B<GGF | EG FA G4 :: dedc B<G G2 | cBAG F<D D2 | dedc B<GGF | 
 EG FA G4 :|  