Catalytic RNAs

by Kevin Ahern, PhD

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    00:00 Now before I go further and talk about processing of other RNAs, I wanna stop for a moment and talk about another function of RNAs; because, they are related to a processing of transfer RNAs that I will talk about.

    00:10 And these are the RNAs that are catalytic in nature.

    00:13 These RNAs actually catalyze chemical reactions that the RNA equivalent of enzymes.

    00:20 We call them ribozymes; because, they catalyze reactions.

    00:25 Now ribozymes play roles in ribosomes and I bring that up up here; because, it's pretty easy to confuse those two terms.

    00:32 A ribozyme catalyzes a reaction.

    00:37 A ribosome is a big structure that makes peptide bonds and proteins.

    00:42 Ribosomes contain ribozymes.

    00:46 Okay. So we can see that in the figure that's shown here, on the right, we see a ribosome and we have seen this figure in another presentation that I have made.

    00:57 In this reaction what's happening is individual amino acids are being joined, as we can see here, in formation of peptide bonds.

    01:06 And during the formation of those peptide bonds, one of the ribosomal RNAs specifically the 23S ribosomal RNA in the case of a prokaryotic system is making the bond between the adjacent amino acids.

    01:20 So that peptide bond formation is happening as a result of action of a ribozyme within a ribosome. Okay.

    01:31 So there are other ribozymes that play roles in processing of individual transfer RNAs. So let me show you one of these.

    01:40 This is a ribozyme known as RNase P.

    01:45 RNase P plays an important function in the final processing that's done on a transfer RNA.

    01:51 Now it's pretty simple but nonetheless it's a catalysis that occurs.

    01:56 On the screen you can see the transfer RNA and at the 5 prime end you can see a black line sort of looped off on the side that 5 prime end has to be processed. It has to have that little piece removed; because, without the removal, the transfer RNA will not function.

    02:15 That piece is removed by RNase P.

    02:19 So in addition to the many functions that RNAs perform in the process of translation, as you can see, they also perform functions of catalysis and in some cases those catalytic function run other RNAs, an amazing group of molecules.

    02:32 Now that's structure removed by RNase P is simply lost. It's not very long but it's long enough that it actually would stop the translation process from happening if it were not removed.

    About the Lecture

    The lecture Catalytic RNAs by Kevin Ahern, PhD is from the course RNA and the Genetic Code.

    Included Quiz Questions

    1. It creates the proper 3’ end of a tRNA
    2. It is a ribozyme
    3. It creates the proper 5’ end of a tRNA
    4. It catalyzes a reaction

    Author of lecture Catalytic RNAs

     Kevin Ahern, PhD

    Kevin Ahern, PhD

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