Any extensive incorporation of the labeled nucleotide depends on {HEAD ~ incorporation} and extension of the analog by {TAIL ~ HIV RT} 
Any extensive incorporation of the labeled nucleotide depends on { HEAD ~ incorporation } and extension of the analog by { TAIL ~ HIV RT }
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL