Translation?

by **victor** » Sat Sep 10, 2005 12:18 pm

OK...sounds that I'm getting more stupid day by day..does tRNA have to bring metionine amino-acid as protein translation precursor?if it's like that, then all the protein in our body have metionine as the first protein sequence..

by **sdekivit** » Sat Sep 10, 2005 3:01 pm

methionine at the start of translation has a special tRNA --> it's incorporated in the formation of the ribosome out of the 60S subunits together with the initiationfactors, which are relased when the 80S ribosome forms.

This is an eukaryotic cell. In a prokaryotic cell, formylmethionine is incorporated in the 50S subunits using a special tRNA.

by **Poison** » Sat Sep 10, 2005 4:15 pm

I think that's why we call it starting code.

by **sdekivit** » Sat Sep 10, 2005 4:44 pm

Poison wrote:I think that's why we call it starting code.

it's not the only one, but it's the most common

This is due to leaky scanning and it's a consensus sequence (Kozak-sequence)

by **Poison** » Sun Sep 11, 2005 3:56 pm

Everybody learns something everyday.

by **victor** » Tue Sep 13, 2005 12:01 pm

Thanks to me because I asked that... :lol:

so Methionine = special tRNA.. :lol:

oh, by the way sdekivit, can you explain what is 80S and 60S?
and another question, if mRNA comes from DNA, then who generates tRNA?is it from mitochondrion?

by **sdekivit** » Tue Sep 13, 2005 4:36 pm

victor wrote:Thanks to me because I asked that... so Methionine = special tRNA.. oh, by the way sdekivit, can you explain what is 80S and 60S?
and another question, if mRNA comes from DNA, then who generates tRNA?is it from mitochondrion?

has something to do with the precipitates of the parts. Thus it says something about it's mass.

by **sdekivit** » Tue Sep 13, 2005 4:37 pm

victor wrote:Thanks to me because I asked that... so Methionine = special tRNA.. oh, by the way sdekivit, can you explain what is 80S and 60S?
and another question, if mRNA comes from DNA, then who generates tRNA?is it from mitochondrion?

tRNA is synthesized in the nucleolus. Remember that we have different RNA polymerases (I,II and III)

by **MrMistery** » Tue Sep 13, 2005 6:25 pm

methionin is transcripted but can be removed if your protein doesn't start with it.
60S and 80S are the sedimentation constants. but you can not add them like mass, because, for example, in prokaryotic cells you got a 50S subunit and a 30S subunit. Added up they will give you 80S which is wrong. But yes, ribosoms are smaller in prokaryotes than eukaryotes

by **victor** » Wed Sep 14, 2005 11:34 am

sdekivit wrote:tRNA is synthesized in the nucleolus. Remember that we have different RNA polymerases (I,II and III)

don't say 'remember'..because it's new for me...hmm..learn something new today..thanks for all..

by **sdekivit** » Wed Sep 14, 2005 3:01 pm

victor wrote:
sdekivit wrote:tRNA is synthesized in the nucleolus. Remember that we have different RNA polymerases (I,II and III)

don't say 'remember'..because it's new for me...hmm..learn something new today..thanks for all..

ok sorry. You know it now then

by **victor** » Thu Sep 15, 2005 11:55 am

Hmm..because it's still new, I'll keep asking for it..(sorry, but I really need to know

)
I've asked my lecturer and he only explained about the process without explaining the difference between tRNA Polymerase I, II, and III. Would you mind to explain them for me?or at least give me some website address that explains these three..

Translation?

Translation?

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