A degree of homology between sequences is a function of {HEAD ~ the number} of matching or homologous positions shared by {TAIL ~ the sequences} 
A degree of homology between sequences is a function of { HEAD ~ the number } of matching or homologous positions shared by { TAIL ~ the sequences }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL