Final answer:
The LTR regions that flank the gag-pol-env genes in linear DNA are long terminal repeats. LTR retrotransposons have two identical LTR sequences that are involved in the integration of the retrotransposon into the host DNA.
Step-by-step explanation:
The LTR regions that flank the gag-pol-env genes in linear DNA are long terminal repeats. LTR retrotransposons, such as retroviruses, have two identical LTR sequences that are involved in the integration of the retrotransposon into the host DNA. The LTRs contain important regulatory sequences that are responsible for the transcription and integration processes.