My Blog List

Monday, May 2, 2011

which came first riboswitches or ribozymes?

We have discussed RNA a lot in the lecture class.  There is much more to talk about regarding these versatile molecules.  For instance, some RNA molecules can act like enzymes.  Origin of life enthusiasts believe that this supports the notion that early life was RNA based....the RNA world hypothesis. 

But on the other hand, some RNA is regulated by many outside factors.  Some of these factors interact with a region on the mRNA called riboswitches, these are binding sites within mRNA for molecules which help control the production of the protein which results from that particular RNA.  These molecules are the "dependent" cousins of the more independent ribozymes.  It would be interesting to see if ribozymes are controlled by riboswitches or they are dependent on them.

1 Provide an example for how riboswitches work.  What is the advantage of having a switch within the mRNA which is used for the translation process? (i.e., why could not the switch be outside the sequence?).

2 Riboswiches show that mRNA sequences are used for more than just making a protein...the same sequence can bind to factors which control the sequence.  What is the significance of one molecule of RNA having multiple functions?

3 Can you envision a scenario for how roboswitches could have evolved?