ShmoopTube

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And here’s your Shmoop du jour, brought to you by message machines. [Phone machine flashing]

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Ever notice how they always seemed to cut off right before the important part of the–––

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Okay, here’s our question:

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The anticodon for the mRNA codon 5’AUG3’ is….

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And here are our potential answers… First, let’s look at what kind of nucleic [Man holding a magnifying glass]

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acid we’re talking about here… mRNA, otherwise known as messenger RNA.

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So we know this is a DNA message that’s being sent out into the cell.

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We also know that mRNA should try texting now and then…seriously, who leaves messages [mRNA texting as people laugh]

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anymore…? Alright, well RNA is different from DNA in

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a variety of ways – it’s single stranded, uses a different sugar in its backbone, and [DNA and RNA stood together]

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it uses a different nitrogenous base. They also start with different letters…

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Bet you didn’t have that difference on your list. That’s why they pay us the big bucks.

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Instead of thymine, RNA uses a base called uracil.

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So we can automatically eliminate A and C, as there’s no U for uracil to be seen. [Answers A and C crossed out]

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That leaves us with two choices: to B, or not to B…or…to D…or…not…

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You get the idea. Let’s take a look at the word anticodon. [Hammer slices word anticodon]

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We see “anti” and “code”. What does that mean?

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Basically, an anticodon is the opposite of what is being coded. So we need to find the

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bases complementary to the ones being encoded by the mRNA. [tRNA molecules added to an mRNA strand]

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Remember the base-pairing rules from DNA? A pairs with T and G pairs with C?

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Now we’re in mRNA world, so A pairs with U and G…well, G isn't a fan of change. G

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still pairs with C. More letters? And we were still wrapping our [Letters floating around mans head]

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heads around the whole “R” and “D” difference…

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So let’s just write down the opposite of what was coded, “AUG.” A goes with U,

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U goes with A, and G goes with C. So the anticodon is UAC. You see?

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Now for take two on that message…and we hope we get to finish, because this is important,

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make sure you don’t open the–––– [man runs to telephone to answer the message]

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