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