Question

Which statement is TRUE?

a) Non-LTR retroposons and SINES have a poly A tail at the 3 end
b) LTR retrotransposons encode endonuclease
c) SINES encode reverse transcriptase
d) SINES in mammals are pseudogenes of RNA polymerase II transcripts

Answer 1

The true statement is that Non-LTR retroposons and SINES have a 3' poly A tail. SINES do not encode enzymes like reverse transcriptase but rely on LINEs, making them non-autonomous retrotransposons.

Step-by-step explanation:

The statement that is TRUE is a) Non-LTR retroposons and SINES have a poly A tail at the 3' end. This is because eukaryotic mRNAs, which are the templates for these elements, typically receive a poly(A) tail at their 3' end during processing. SINES (Short Interspersed Nuclear Elements) do not encode reverse transcriptase or any enzymes required for their transposition; instead, they rely on the proteins produced by autonomous elements like LINEs (Long Interspersed Nuclear Elements). LINEs encode the necessary enzymes, which include reverse transcriptase and endonuclease for their own transposition. Therefore, SINES are considered non-autonomous retrotransposons and are often retroposons, which can be pseudogenes or derived from RNA polymerase transcripts.