Talk:Ribosome

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Contents

[edit] Ribosome creation

It would be useful to describe theories how ribosomes were created in evolution.

Yes, it would. But it might also be premature to commit such a discussion to an encyclopedia, as work testing a leading hypothesis has really just started to be published. The Noller lab, in gradually stripping proteins from native ribosomes without totally destroying activity, helped advance the idea that the RNA, rather than the proteins, participate in crucial ribosome function. More recently, the Strobel lab has been trying to identify more exactly (large subunit RNA is still a huge molecule!) what part of the RNA is responsible for peptidyl transfer:

  G. W. Muth, L. Ortoleva-Donnelly and S. A. Strobel, A single adenosine
  with a neutral pK[a] in the ribosomal peptidyl transferase center,
  Science 289, 947-950 (2000).

It might be useful to have a good idea of how it all works before going very far in trying to describe inferences as to how it came to work that way.

It is true that theories about the evolution of ribosomes, although extremely intriguing, are quite speculative at this time. However, it may be useful to mention the auto-catalytic capabilities of RNA molecules in general (the 'RNA world' hypothesis) as a possible starting point for the modern translational machinery. Wikipedia link: RNA_world

WK

It would be much more appropriate for Wikipedia if the RNA World POV were lost from the article. There is no proof at this time that an "RNA World" existed, and using the provocative name is more prejudicial than probable. ManVhv 08:07, 15 July 2007 (UTC)
Also, please sign your talk page comments with four tilde characters (~~~~) in the future. To add a comment, indent your reply, rather than inserting horizontal lines. Thanks! ManVhv 08:08, 15 July 2007 (UTC)


[edit] Simplified Structural Image

It would be nice if there is a simplified image of the ribosome at the head of the document and then using the highly detailed structural images in the mid-section. I'm in the process of finding a diagram for this purpose as well as for the translation page. --G3pro 13:59, 15 Nov 2004 (UTC)

[edit] More Structure

I am writing my thesis about the ribosome, so I plan to expand the structural aspects of this page. Maybe some of the chemistry involved. Feel free to change anything I add. I like how the page starts, very general, so I will add to the bottom.

I just uploaded an original picture of the 50S subunit; the 30S and 70S subunits are forthcoming.

--vossman 14:04, September 1, 2005 (UTC)

Hi.

In my opinion, and from reading the ribozyme page, Ribosomes are not ribozymes (see comment in opening para of article). For the ribosome to work it requires the protein scaffold, it is not an RNA only enzyme. So at best ribosomes might be called ribo-proteozymes. Just a thought. Reveldrummond 00:44, 16 December 2005 (UTC)

I guess you could argue that a ribozyme might have protein subunits. This recent article says, "the ribosome is a ribozyme".
The ribosome is a ribozyme, because all the chemistry is performed by the RNA. Efforts are ongoing by the Green lab at Hopkins and Strobel and Steitz labs at Yale to produce a protein free peptidyl transferase RNA, but so far have been unsucessful. --vossman 03:25, 16 December 2005 (UTC)

FIGURE WRONG!! I am soory, I don't know the proper way of writing here, but I just wanna mention that The figure shows WRONG unit of lenght, the ribosome is not that big. it is aproximately 200 A not nm or 20 nm.

[edit] Amount of rRNAs in subunits

The mammalian 40S subunit contains 18S rRNA. The 60S subunit contains 5S, 5.8S and 28S RNA. This is not consistent with the text that says that each subunit contains one or two rRNAs. Prokaryotic ribosomes have indeed 1 or two rRNAs: the 30S subunit contains 16S rRNA, the 50S subunit contains 5S and 23S rRNA.--User:AAM | Talk 20:05, 11 May 2006 (UTC)

[edit] Size of Ribosome [nm]

"FIGURE WRONG!! I am soory, I don't know the proper way of writing here, but I just wanna mention that The figure shows WRONG unit of lenght, the ribosome is not that big. it is aproximately 200 A not nm or 20 nm."

I just wanted to emphasize that the size of ribosome in this article (the size of ribosome in nm is desplayed below the ribosome in figure 2) is about 10 times bigger than in reality, and there is some difference in size (nm) between the eukaryotic and prokaryotic ribosome. See http://en.wikibooks.org/wiki/Cell_biology:Size_of_cells or http://nai.arc.nasa.gov/news_stories/news_detail.cfm?ID=137 for quite exact size in nm.

See link TimVickers 20:56, 31 March 2007 (UTC)
Erm, 200 Angstroms == 20 nm by definition. That is in the correct range for ribosomes, it's ~3000 nucleotides packed with a few dozens proteins. Even the links you provided confirm that. -Lp 70.81.26.125 19:56, 1 September 2007 (UTC)

[edit] Where are they produced

Can we include information as to what organelle produces Ribosomes, or did I just miss it? AdamBiswanger1 23:44, 25 October 2006 (UTC)

In prok's ribosomes form in the cytosol (no organelle), but in euk's ribosomes are produced in the nucleolus and exported. This page is very prok focused, so I don't think it fits in. --vossman 01:12, 26 October 2006 (UTC)

[edit] Definition of Ribosomes/Organelles

Organelles are generally defined as having lipid or phospholipid membranes. Ribosomes have no such membranes (they consist only of rRNA and proteins), so they shouldn't be technically classified as organelles, yet the article classifies them as such anyway. Have I missed something here? 68.221.210.250 01:20, 4 January 2007 (UTC)JackMerridew

As discussed at Organelle, different people use the term "organelle" in different ways. Some people count ribosomes as a type of organelle. --JWSchmidt 01:39, 4 January 2007 (UTC)
I agree with JWSchmidt, organelle isnt a well defined term and is used in many ways. - Zephyris Talk 10:06, 4 January 2007 (UTC)
Okay, I can accept that. It would be nice if there were more definitive criteria for defining an organelle, though. I admit to some confusion. —The preceding unsigned comment was added by 68.221.216.6 (talk) 22:18, 5 January 2007 (UTC).
I can't accept that. Organelles are membrane bounded compartments or at least discrete membrane associated assemblies. Some people try to stretch

the definition to the cytoskeleton, but even this distorts the meaning of organelle. I'm a professor at a medical school, and I find that this definition has confused many students. The Ribosome is properly termed a macromolecular assembly or macromolecule, not an organelle. Sludtke42 20:57, 8 May 2007 (UTC)

Figuring that silence doesn't help, rather than removing any remark, I added a sentence that states that "organelle" is contested. I also put a matching remark in the organelle article. Tom Lougheed 21:13, 18 August 2007 (UTC)

Personally, I would never describe a ribosome, spliceosome, exosome, proteasome or degradosome as organelles. These are all just large enzymes. Tim Vickers 21:36, 18 August 2007 (UTC)

[edit] Please revise

In the section structure it is said that prokrayotes have 70S ribosomes (30S sub nit and 50S sub unit) Doesn't that make 80S :S

Not needed. Logically you would think so, but S refers to Svedburg units which are bases on density/sedimentation so the units are NOT additive they are determined experimentally. Hichris 15:44, 14 February 2007 (UTC)

denis kostic

[edit] simple

simpler terms mabyOt108 02:03, 15 August 2007 (UTC)

simple:Ribosome. Tee-hee, I can't help but find that wikipedia funny :') Jack the Stripper 00:41, 30 August 2007 (UTC)

[edit] Subunit function

The article currently states that the large subunit contains the A, P, and E sites for tRNA binding. I believe that these three sites are, in prokaryotes at least, located on the 16S rRNA and, therefore, on the small 30S subunit, not the large 50S subunit. Am I wrong? Is this true for eukaryotes as well? Nllewellyn 14:27, 3 September 2007 (UTC)

Hm, I wonder if you can really pinpoint the sites to one location (being the 16S rRNA or whatever). In enzymes catalytic or allosteric sites aren't always part of one subunit but can be spread over both, so therefore I'd say that the A, P and E sites are formed by both the 30S and 50S subunit.. In any case the larger part of any of the 'gaps' is situated in the 50S part. Then again, the interaction between tRNA, mRNA and rRNA does occur in the 30S subunit... But correct tRNA loading is regulated by more than that. Jack the Stripper 18:08, 9 September 2007 (UTC)
Thanks for the thoughtful response, Jack. You've expressed better what I was thinking myself: that the binding pockets are formed by both units, with the 50S contributing more of the pocket, while the tRNA-mRNA-rRNA association occurs locally on the 16S rRNA in the 30S subunit. Thanks for taking the time to help clear that up for me. Nllewellyn 10:15, 10 September 2007 (UTC)
You're welcome :) Jack the Stripper 12:12, 10 September 2007 (UTC)

There is an extra parenthesis in the first line of function.

"Ribosomes are the workhorses of protein biosynthesis, the process of translating RNA) into protein."


[edit] Ribosomes are found in cells containing nuclei

I just noticed that the sentence "Ribosomes (from ribonucleic acid and "greek: soma (meaning body)") are complexes of RNA and protein that are found in all cells that contain nuclei. " is a bit misleading, because "nucleus" is a membrane bound organelle which exists in all eukaryotic organisms, whereas ribosomes also exist in prokaryotes which by definition do not have nucleus, but a nucleoid which doesn't have membrane. Am I right? If I'm not, then this shouldn't be corrected in this article Kazkaskazkasako 18:52, 11 November 2007 (UTC)

Prokaryotes have ribosomes as well. Jack the Stripper 17:39, 14 November 2007 (UTC)

[edit] 16s?

The 16S rRNA seems to have disappeared from the structure of the bacterial small subunit (was it ever there??) —Preceding unsigned comment added by 130.126.91.51 (talk) 22:06, 30 January 2008 (UTC)