Craft a composition that integrates the assigned alphabet-related musical pattern and the provided melodic theme.
X:1
L:1/8
M:4/4
K:G
['G<GAB dBBg G<GAB', 'z2 f g>fed edBf g>agf e<B z']  
X:1
L:1/8
M:4/4
K:G
 G<GAB dBBg | G<GAB d<B z2 :: f | g>fed edBf | g>agf e<B z f | gfed ef g2 | G<GA>B dBBg | 
 G<GA>B d<B z2 ||  