Answer:
a. MicroRNAs (miRNAs) bind to complementary sequences in mRNA and block its translation.
b. Piwi-associated RNAs (piRNAs) reestablish appropriate methylation patterns in the genome during gamete formation.
Explanation:
MicroRNAs
These are the small non-coding RNA molecule. These RNA consist of about 22 nucleotides. MicroRNAs are found in animals, plants and some viruses,
MiRNAs function
MicroRNAs also represented as miRNA function through base-pairing with complementary sequences of mRNA molecules. Due to this base pairing it functions as RNA silencing and regulation of gene expression.
Piwi-interacting RNA
piRNA expressed in animal cell. piRNA are the small non-coding RNA molecules which form RNA-protein complexes.
Piwi-interacting RNA Function:
Function of these complexes are epigenetic and post-transcriptional silencing of transposons.
Small interfering RNA :
siRNA molecules are the small pieces of double-stranded (ds) RNA. There length is about 21 nucleotides long. siRNA have 3' (3 prime) overhangs
Small interfering RNA Function:
siRNA overhangs are used to "interfere" protein translation. They perform this function by binding and degradation of mRNA at specific sequences
