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Ribosome

Definition

noun, plural: ribosomes

(Science: cell biology)

(1) A minute particle composed of protein and ribonucleic acid (RNA) that serves as the site of protein synthesis.

(2) A molecule consisting of two subunits that fit together and work as one to build proteins according to the genetic sequence held within the messenger RNA (mRNA). Using the mRNA as a template, the ribosome traverses each codon, pairing it with the appropriate amino acid. This is done through interacting with transfer RNA (tRNA) containing a complementary anticodon on one end and the appropriate amino acid on the other.

(3) A sphere-shaped structure found in the cytoplasm of prokaryotic and eukaryotic cells. Some ribosomes occur freely in the cytosol whereas others are attached to the nuclear membrane or to the endoplasmic reticulum (ER) giving the latter a rough appearance, hence, the name rough ER or rER.


Supplement

Ribosomes of prokaryotes (e.g. bacteria) are smaller than most of the ribosomes of eukaryotes (e.g. plants and animals). However, the plastids and mitochondria in eukaryotes have smaller ribosomes similar to those in prokaryotes – a possible indication of the evolutionary origin of these organelles.

In mid-1950s, ribosomes were first observed as dense particles or granules by George Palade with his electron microscope. In 1958, the term ribosome was proposed by the scientist, Richard B. Roberts.


Word origin: from ribonucleic acid and Greek: soma, meaning body.

Related forms: ribosomal (adjective).
Related terms: ribosome binding site, ribosome-lamella complex.


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translation from DNA

... translated directly from the RNA (as nowadays) but when DNA started to work as information carrier, there would have to be too big changes in the ribosome and everything so it couldn't be possible but rather the transcription system evolved (as that's pretty similar to replication).

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by JackBean
Tue Sep 30, 2014 8:16 am
 
Forum: Molecular Biology
Topic: translation from DNA
Replies: 2
Views: 212

Re: translation from DNA

That's a reasonable idea. I can imagine a ribosome directly binding to DNA to translate the DNA codons directly into protein. We can't really tell why that didn't happen, as much of the early development of life occurred far in the past and left ...

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by jonmoulton
Mon Sep 29, 2014 3:03 pm
 
Forum: Molecular Biology
Topic: translation from DNA
Replies: 2
Views: 212

What makes dominant allele dominant?

... to protein post-translational modifications. There can be mutation in the promotor changing significantly expression. If the binding of ribosome will be impaired, there will be much less of protein made. Single point mutations can lead to differences in binding of miRNAs. On the protein ...

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by JackBean
Thu Feb 27, 2014 5:20 pm
 
Forum: Genetics
Topic: What makes dominant allele dominant?
Replies: 7
Views: 4375

peptidyl transferase

Hey there. I have a little problem. :( PTC is an enzyme which catalyzes the peptide formation reaction. It is located in 60s subunit of ribosome. EC 2.3.2.12 . I actually need a pdb file of ptc for my docking issue. how can I find it??

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by Parisa
Tue Nov 05, 2013 10:11 pm
 
Forum: Cell Biology
Topic: peptidyl transferase
Replies: 2
Views: 1240

peptidyl transferase center?!

Hey there. I have a little problem. :( PTC is an enzyme which catalyzes the peptide formation reaction. It is located in 60s subunit of ribosome. EC 2.3.2.12 . there are some pdb IDs like 3j3b n 3j3f but not for the pure protein. I actually need a pdb file of ptc for my docking issue. how ...

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by Parisa
Tue Nov 05, 2013 12:12 am
 
Forum: Bioinformatics
Topic: peptidyl transferase center?!
Replies: 1
Views: 1164
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