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Protein synthesis

You'll have to pardon my lack of knowledge, I'm only a GCSE student so bear with me.

Apparently ribosomes aid in protein synthesis. They have the enzymes required to create peptide bonds between the amino acids.
But ribosomes themselves are also made of proteins.

So who synthesized the proteins that make up ribosomes? :eek:

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Reply 1

Revenged

yo-less

The proteins are still synthesised by ribosomes...

They are modified by another organelle after they are synthesised - Golgi apparatus...

Reply 2

yo-less

Sir Revenged

The proteins are still synthesised by ribosomes...

They are modified by another organelle after they are synthesised - Golgi apparatus...

That's all very well but who synthesized the proteins that make up a ribosome?!

*PS: I thought the endoplasmic reticulum modifies the protein :confused:

Reply 3

Mustard-man

yo-less

The nucleoplasm contains DNA and RNA. Ribosomes are made out of ribosomal RNA (rRNA). rRNA is made in the nucleolus (which is that small dark patch in the nucleus) from instructions contained in DNA. The rRNA is then combined with protein to give the ribosome.

mRNA --> protein
protein + rRNA --> ribosome

Ah, I see your point now. Well you can't really answer that question; sort of like- what came first, the chicken or the egg? There are many things in Biology which you have to simply remember, cannot be explained.

You could say that protein from your mother was needed to create the fetus (you), therefore you were able to get hold of the protein through the placenta. But that goes on to where your mother got her protein from, etc.....

Reply 4

Mustard-man

yo-less

*PS: I thought the endoplasmic reticulum modifies the protein :confused:

Nope, the golgi body's function is to modify and package the proteins.

The smooth endoplasmic recticulum is involved with the synthesis and transport of lipid molecules. The rough endoplasmic reticulum is concerned with the synthesis, storage and transport of protein.

Hope that helps.

Reply 5

nikk

It might be helpful for you to think of a primordial ribosome possessed by one of our single-celled ancestors in the distant past. This primordial ribosome most likely was entirely composed of rRNA. Only over the subsequent course of evolution did proteins become associated with ribosomes, presumably stabilising their structure and increasing their catalytic activity.

That has come from the top of my head, so don't quote me on it, but that would be a sound (and probably most likely) evolutionary explanation to your question.

Also, remember that RNA can have catalytic activity (not all enzymes are necessarily proteins, although the enzymatic activity of some mRNA is usually referred to as ribozymes).

Reply 6

yo-less

nikk

That's possibly the best explanation I've heard so far.

I know you said not to quote you, but do you mind if I do? Our bio teacher gave this question for us to muse about and so far no one has come up with any theories. Don't worry, I'll give you full credit :wink:

Reply 7

nikk

yo-less

Yeah oh course. Feel free to take the credit if you want (provided they agree, otherwise you can blame it on me :wink:

).

A Russian biologist once said that "Nothing in biology makes sense except in the light of evolution". And this is very true. If you ever come up against a problem such as the ribosome one you asked about, it is often helpful to think about it in evolutionary terms.

I'd be interested to see if your teacher thinks this is the correct answer, so it would be great if you could post up his/her response. :smile:

Reply 8

Rach 2nd

It is the 23s rRNA, which has ribozymic activity. The proteins in ribosomes have mainly structural roles. Before the evolution of protein catalysts, RNA functioned as genes and enzymes and is believed by many to be the driving force for pre-biotic evolution.

Reply 9

Nuheen

Isn't this supposed to be GCSE stuff?

No I meant that the answer shouldn't be so complex. It is only GCSE.

Reply 12

yo-less

nikk

Yeah oh course. Feel free to take the credit if you want (provided they agree, otherwise you can blame it on me :wink:

Hah, I didn't tell my teacher today but I'll tell her tomorrow. I discussed it with a fellow bio nerd though and we came to the conclusion that it was the most sensible explanation possible (to us, atleast).

Nuheen

No I meant that the answer shouldn't be so complex. It is only GCSE.

He's right, I am a GCSE level student :p:

I don't think our teacher wanted a proper answer, it was sort of a question to ponder on if we(the class) could be bothered. Naturally, I'm the only one who has an answer :eek:

I haven't told the teacher yet.

But Nikk's post was quite enlightening. Props to him/her.

Reply 13

Comp_Genius

yo-less

the cell which gave rise to the cell you are talking about - all cell material comes from a precursor which already has all necessary bits like ribosomes. :p:

Reply 14

nikk

Nuheen

No I meant that the answer shouldn't be so complex. It is only GCSE.

To be honest, that kind of question is probably way above the level of questions that would be asked in a GCSE exam. Hence, to answer it in any kind of reasonable fashion, one must include the details discussed. At GCSE, you do not need to know these details, and so if we were restricted to answering at that level, the answer would have been something like, 'because they are'. Which wouldn't be very satisfactory.

Reply 15

danni_bella

What about amino acids, aren't they the molecules which make up the proteins? Or is there something in between? I SWEAR there is something in between, we did this last year but I forget now :redface: