Question

Among the newly-discovered small noncoding RNAs, one type reestablishes methylation patterns during gamete formation and blocks expression of some transposons. What are these types of RNA called

Answer 1

piwi-interacting RNAs (piwi-RNAs)

Explanation:

The piwi-interacting RNAs (piRNAs) are small non-coding RNAs (from 21 to 31 nucleotides) that are abundantly expressed in the animal germline in order to control the expression of target sequences. The piRNAs associate with PIWI proteins from the Argonaute family (AGO) to form an effector complex that binds to complementary target DNA/RNA sequences. These small ncRNAs target Transposable Element (TE) transcripts to suppress TE expression and thus maintain genome integrity. The piRNAs can also guide epigenetic remodeling complexes that suppress gene expression by methylation of target DNA sequences in the nucleus.