Miracles of Science #3: RNA World Part 3

There are a wide range of different types of RNAs, and almost all of them have gone through some controversy about whether they exist, whether they're real, and whether they do something important.

And those wars have generally been fought, and the victor has always been the, the, the protagonist, the people who said, "Yeah, these RNAs are there, and they're important." So I think you can divide the RNA world into three or four categories.

I'll do that for you.

The first set of RNAs to talk about are translational RNAs.

What does that mean? It means RNAs whose primary job is to translate nucleic acid language into amino acid language and create the proteins that you need, and the proteins are the workers of the cell.

So what are the RNAs that play a role in making the proteins that you need? Well, the first is the ribosomal RNAs.

Now, ribosomal RNAs are by far the most abundant RNAs in the cell, hundreds of thousands, millions of copies of ribosomal RNAs because they are structural RNAs, and they need to be available to make hundreds and hundreds of ribosomes, the, the machines that, um, that you use to make proteins.

So you recall that genetic information is transcribed into RNA, a molecule that's almost exactly the same as DNA, and that's why the, the process is called transcription and uses the same Morse code equivalent kind of language.

There's simply four nucleotides, that's it, that comprise the language of nucleic acids.

Beautifully simple.

You have m-- twenty basic amino acids that go into forming proteins.

And so you can think of the language of proteins as being the amino acid language and about as complicated as English.

So somehow you have to take this simple dot-dot dash dot-dot kind of language and convert that into something like English.

And that's what the, the translational RNAs do for a living.

So again, think about Morse code in a, in a ticker tape and turning that into English.

Well, you can see how incredibly complicated that would be, and you can imagine how important it would be because without it, you don't have the proteins that do the work that keep the cell alive.

And that work then is done by ribosomes.

Ribosomes are just RNA protein machines that can take information that's in a Morse code and convert it into proteins.

Ribosomes are comprised of two subunits, one smaller, the forty S subunit, and one larger, the sixty S subunit.

So what's an S? Don't worry about it.

It's just a term that measures the size of very big protein RNA complexes, and so it's no different.

When I say S, that's me-- that's no different from saying you weigh a hundred and forty pounds.

Uh, it's just that simple.

Now, to make the two subunits, the forty S subunit and the sixty S subunit of ribosome, you use ribosomal RNA as an architectural RNA.

It's used to form those structures out of ribosomal proteins.