The diagram of a eukaryotic ribosome shown below contains seve...

Question

The diagram of a eukaryotic ribosome shown below contains several errors.

Diagram of a eukaryotic ribosome with labeled sites and an arrow indicating movement along mRNA, highlighting errors.

Examine the diagram carefully, and identify each error.

Accepted Answer

Hi, everyone. Welcome back. Here's our next problem. Eucaryotic ribosomes are composed of two subunits, a small 40 S subunit and a large 60 S subunit that combine to form a functional blank ribosome. And our answer choices are a 70 S B, 80 S C, 90 S or D 100 S. So we know that our ribosome has these two subunits just draw sort of a big oval on top of a small sort of flattened oval, the M R N A, this sort of held on the small subunit on the bottom and the T R N A S come in to the top subunit. And that's generally the, a really rough outline of the structure here. So the 60 S subunit on the top and the 40 S subunit on the bottom. But what does that letter S mean? And that letter S stands for a Svedberg unit, which is used to categorize the size of these subunits of the ribosome itself. And the Svedberg unit is a measure of the sedimentation rate of a particle in a centrifuge. So when spun under super high speeds and uh generating a centrifugal field at what point does a certain size particle become sediment. And so it measures size in a way that can be observed easily with things like ribosomes. And it's therefore, it's not a direct measure of size in terms of, we can't just add together 60 and 40 and get 100. The way you could if you were measuring, say the mass of those two subunits. So we just have to kind of know that the entire eucaryotic rabbi and that's important is choice B A s in size. So as we said, we can't just add them together. So choice D 100 s is not correct. That's kind of in there to mislead us a little bit procaryotic ribosomes have a total size of choice. A 70 S, that's why A is not correct. And then C 90 S is just not the correct number. So again, something we just have to know we can't figure out by adding together as it's this observed sedimentation rate that this Svedberg unit measures. So again, you carry out ribosomes composed of two subunits, 40 S and 60 S. They combine to form a functional choice B A DS ribosome. See you in the next video.

The diagram of a eukaryotic ribosome shown below contains several errors.

Examine the diagram carefully, and identify each error.

Key Concepts

Eukaryotic Ribosome Structure

Ribosomal RNA (rRNA)

Translation Process

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