Question

HOW DOES THE WOBBLE EFFECT WORK DURING TRANSLATION? ONE ANTOCODON CANT POSSIBLY BIND WITH THREE CODONS OF A SPECIFIC AMINO ACID LIKE ISOLEUSINE.

Answer 1

So, first lets look at the codons for leucine.

CTT
CTG
CTC
CTA

They're all the same except the last spot (often called the wobble base).

So there are 4 types of tRNA floating around in a cell that have leucine attached. There are tRNA with CTT attached to a leucine AND tRNA with CTG attached to a leucine, for example.

But why is the last spot often the variable one for codons that code for the same amino acid? This has to do with RNA binding properties.

Imagine we have RNA that has the codon CTT in it. The binding happens 3' to 5' (just pretend its left to right). So the C binds to a G first, then (and only then) can the T bind to an A, then the last T can bind to another A. This is the easiest way for it to bind. So as long as the first few are bound you have a pretty strong bond between the mRNA and the tRNA. So sometimes that last one can not be bound and the ribosome will still attach the amino acid to the peptide. This can be a problem if you wanted a leucine but the ribosome screwed up and attached a serine, for example. But because the last spot is wobbly, the ribosome can screw up and no matter what we are still always attaching a leucine. That last spot does not have to bind as strongly as the first one and we still get the correct amino acid.

Think of it like a zipper on a hoodie, you start from the bottom zipping up, but at the top they can still be open but your hoodie doesn't fly open.

Answer 2

im not quite sure ik undertsand ur explanation. it seems like you didnt proofread your explaination beforle hittting the post button....please could you explain vividly

Answer 3

Don't see any typos. Let me take a different track.

For the last spot in the codon to bind to an mRNA the first two HAVE to be bound already. But for the bind to be good enough for the ribosome to actually add the amino acid to the polypeptide you don't always need that last one. Since the first two HAVE to be bound, they cannot vary. But the last one is not vital for the ribosome to decide it has the right tRNA attached. So that third site can vary, and the ribosome can still attach the amino acid to the polypeptide.

So if the codon table wasn't redundant what would happen?

instead of CTT, CTG, CTC, and CTA, all coding for leucine they may all code for different amino acids. If this was the case when the ribosome messes up and lets a CTG tRNA attach to a CTT codon the protein is going to be WRONG. So evolution favored organisms where the tRNA for CTT and CTG coded for the same amino acid, so that if the ribosome messes up it does not affect the protein.

Think about the hoodie analogy. The left side of your hoodie is the tRNA the right is the codon. If you zip your hoodie up just a little bit the zipper will slowly slip down until your hoodie flies open. If you zip it up 2/3 of the way though it isn't going to fly open, it is zipped enough to stay stuck together. If the hoodie is zipped enough to stay together then the ribosome will take the tRNA (left side of your hoodie) and attach it to the growing protein. It would be even better if your hoodie was zipped ALL the way, but it is not necessary.

Answer 4

WUDNT THIS AFFECT THE ENERGY USED TO BIND TO AMINO ACID CHAIN SINCE UR JUST HAVING 2/3...ITS NOT A COMPLETE LOVE AT FIRST SIGHT..PEPTIDE BOND WUDNT BE AS STRONG...OR DOES IT NOT MATTER?

Answer 5

fabbyrob, do u have skype?