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We speak student!

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Molecular Genetics

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RNA

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A la Shmoop

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We are here with Dr. Ruth Tennen

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to talk about molecular genetics

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here at Shmoop global headquarters

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in Mountain View, CA.

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And we're gonna cover genetic code and DNA/RNA structure.

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All right, so, moving right along,

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what is RNA? We've talked about DNA.

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What is ribonucleic acid?

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Yeah, so, it's very similar to DNA,

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but it has that extra oxygen.

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So it's also a polymer of nucleotides.

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One big difference is, rather than the thymine

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as one of the bases, it's uracil. So "T" goes to "U."

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- Got it. - But they're basically the same.

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Otherwise, their function's very different.

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And there's other differences as well. So, for example,

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DNA is always double-stranded,

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RNA tends to be single-stranded, then fold back on itself.

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So they have different functions in the cells,

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but they, structurally, are pretty similar.

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Got it. Okay.

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Then we have subsets of RNA -

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mRNA, rRNA, tRNA.

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Can you explain to us what are those elements

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and how do they function?

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What are the different kinds of RNA?

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So, kind of a major RNA that we always hear about is mRNA,

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which is the intermediate between DNA and protein.

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So DNA gets transcribed into mRNA, which gets translated into protein.

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So that's kind of like the "famous" RNA.

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But there are what's called non-coding RNAs,

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that aren't turned into proteins, basically.

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So tRNAs are transfer RNAs and those are involved in protein synthesis.

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They help with the ribosome.

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There are ribosomal RNAs which, again,

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they don't get turned into proteins, but they actually

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function as RNAs.

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But walk us through, like, how does it work?

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What's the RNA process? Why do we need these interstitial steps

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to make things happen so that everything's okay?

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Is it like a human checking mechanism to be sure that genes

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are all happy and healthy?

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And if they don't, the cell goes away,

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so we heal properly?

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[ whooshing ]

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Why do we need RNA?

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One reason is that DNA -- you want it to be super stable.

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Right? Because it gets passed down through all the generations

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- and we need to keep it the same. - Sure.

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By having an intermediate, basically you can say,

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"Okay, I wanna turn on this gene.

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And I'm gonna make a ton of copies of the messenger RNA."

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So you can have a ton of different copies

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that ultimately will get degraded when they're not needed anymore.

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Whereas you wouldn't wanna chew up the DNA

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when it wasn't needed anymore.

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So it's kind of a way of...

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How do they get degraded?

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So this is like taking a DVD and copying it,

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and copying it again and again and again

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and after a while it just -- like the data isn't as clear?

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So each copy, actually, is originally from the DNA.

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So each copy's just as good as the previous one.

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But, eventually, let's say a cell wanted to turn on a gene

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to do a certain thing.

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So it said, "Okay, I'm gonna need to metabolize sugar right now

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so I gotta turn on my sugar-metabolizing gene."

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And then the sugar goes away;

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it doesn't need that protein anymore that would do that.

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So then there are enzymes that come in

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and just chew up and get rid of the RNA. It's extra.

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[ woo-woo-woo ]

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Got it. So it degrades not in its quality gets less;

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it degrades in that its utility is lower.

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Exactly. The abundance ends up going down

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when it's not needed anymore.

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Got it. And our body has stuff that regulates that?

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Is that like the...?

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You know, I don't know in terms of actual hormones and things,

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but at the cellular level, there's like a million enzymes

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that are always pucking around and --

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Basically, these processes are super important,

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so there's tons of layers of regulation

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just to make sure everything's pretty tightly constrained.

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Got it. 'Cause you've got a lot of replications happening.

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I mean, it kind of reminds me of a computer.

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It's like if you don't have lots of checks in your database,

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- Exactly. - you're gonna print bad data.

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[ whoop ]

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What is RNA?

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What are the different kinds of RNA?

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Why do we need RNA?

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[ woo-woo-woo ]

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