So when nucleotides found in close proximity along that particular polynucleotide chain interact via these hydrogen bonds between the nucleotide bases that can form a secondary structure. In fact when we have these nucleotides down far away interacting via these base pairings then that can form tertiary structure. So just like proteins contain this secondary and tertiary structure because these bases along the polynucleotide chain of the RNA molecule can interact with one another RNA molecules can also form secondary and tertiary structure. And this complexity, this ability of the RNA molecule to form this complex structure gives it the ability to function in many different ways. And this means just like proteins can function biological catalysts RNA molecules can also act as biological catalysts as we'll see, for example when we discuss the process of protein synthesis. So in protein synthesis we have these cellular machinery structures known as ribosomes and ribosomes contain RNA molecules and these RNA molecules act as biological catalysts to basically synthesize that protein chain.