Design a musical composition incorporating the alphabetic expression of the chosen structure and the provided melodic theme.
X:1
L:1/4
Q:3/4=60
M:3/4
K:G
['z z']  
X:1
L:1/4
Q:3/4=60
M:3/4
K:G
 D | B3 | c3/2 B/ c | (e3 | d2) b/b/ | b a g | g f e | (^c3 | d2) ^c/d/ | a3 | a2 b/a/ | 
 g ^c/d/ d | ^c/e/ d ^c/e/ |"^'etc...'" z z z | z z z |]  