Final Answer:
Retrotransposons derived from RNA polymerase II (RNA pol II) promoters include Short INterspersed Elements (SINEs), with the Alu element in humans being a notable example.
Step-by-step explanation:
Retroelements derived from RNA polymerase II (RNA pol II) promoters are primarily represented by retrotransposons known as SINEs (Short INterspersed Elements).
SINEs are non-coding sequences that exploit the cellular transcriptional machinery, including RNA pol II, to produce RNA transcripts. One well-known example is the Alu element in humans, which originated from 7SL RNA.
Alu elements are short, approximately 300 base pairs long, and their amplification has played a significant role in shaping the human genome. These retrotransposons lack coding capacity for their own reverse transcriptase and integrase enzymes, relying on the cellular machinery for retrotransposition.
The transcription and retrotransposition of SINEs illustrate the intricate interactions between retroelements and host cellular processes during evolution.