Prokaryotic Translation | Elongation and Termination

Elongation of the polypeptide chain involves addition of amino acids to the carboxyl end of the growing chain. The growing protein exits the ribosome through the polypeptide exit tunnel in the large subunit.
Elongation starts when the fMet-tRNA enters the P site, causing a conformational change which opens the A site for the new aminoacyl-tRNA to bind. This binding is facilitated by elongation factor-Tu (EF-Tu), a small GTPase. For fast and accurate recognition of the appropriate tRNA, the ribosome utilizes large conformational changes (conformational proofreading). Now the P site contains the beginning of the peptide chain of the protein to be encoded and the A site has the next amino acid to be added to the peptide chain. The growing polypeptide connected to the tRNA in the P site is detached from the tRNA in the P site and a peptide bond is formed between the last amino acids of the polypeptide and the amino acid still attached to the tRNA in the A site. This process, known as peptide bond formation, is catalyzed by a ribozyme (the 23S ribosomal RNA in the 50S ribosomal subunit). Now, the A site has the newly formed peptide, while the P site has an uncharged tRNA (tRNA with no amino acids). The newly formed peptide in the A site tRNA is known as dipeptide and the whole assembly is called dipeptidyl-tRNA. The tRNA in the P site minus the amino acid is known to be deacylated. In the final stage of elongation, called translocation, the deacylated tRNA (in the P site) and the dipeptidyl-tRNA (in the A site) along with its corresponding codons move to the E and P sites, respectively, and a new codon moves into the A site. This process is catalyzed by elongation factor G (EF-G). The deacylated tRNA at the E site is released from the ribosome during the next A-site occupation by an aminoacyl-tRNA again facilitated by EF-Tu
The ribosome continues to translate the remaining codons on the mRNA as more aminoacyl-tRNA bind to the A site, until the ribosome reaches a stop codon on mRNA(UAA, UGA, or UAG).
Termination occurs when one of the three termination codons moves into the A site. These codons are not recognized by any tRNAs. Instead, they are recognized by proteins called release factors, namely RF1 (recognizing the UAA and UAG stop codons) or RF2 (recognizing the UAA and UGA stop codons). These factors trigger the hydrolysis of the ester bond in peptidyl-tRNA and the release of the newly synthesized protein from the ribosome. A third release factor RF-3 catalyzes the release of RF-1 and RF-2 at the end of the termination process.

[@mol_biologist30]

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Just amazing Sir. Keep it up

[@jottingthoughts]

Your videos are great for me, I'm a visual learner so I greatly appreciate your concise and clear animations!

[@demrovbeta2289]

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[@khaledghanem1530]

Thanks, really helpful👍👍

[@ashritpattanayakfan]

Can't thank you enough, Sir

[@mariyamsiraj3929]

These videos are so diligently made. Thank you sir for your efforts. You make such tough concepts crystal clear!!

[@hussainbiology]

thanks for appreciation..Glad it helps

[@archanadas1795]

How does the 60S subunit and the 40S subunit dissociated to 50S and 30S… since in the initiation step you mentioned the ribosomes to be of 60S subunit and the 48S subunit (from where all the factors got dissociated)

[@AjGaming-vx2pc]

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your all video series are awesome...

[@hussainbiology]

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[@sakshikumari9626]

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[@hussainbiology]

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Glad it helps.✌️

[@aima7890]

Thanks 😊

[@Scholarship_hunters]

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[@hussainbiology]

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[@user-cd5bk5kl2q]

Can i get notes of your videos? I really need it for my exam.

[@sajinasasi2603]

No words sir it's so great

[@hussainbiology]

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[@nishatfatima2091]

Sukriya sir , your video really helpful in revision ...🤗

[@hussainbiology]

Keep sharing and supporting...✌️

[@ammaramehak9473]

nice videos, keep it up .

[@hussainbiology]

thanks for appreciation.. Glad to know that it helps ✌️

[@dhrubarajbongshi4653]

ধন্যবাদ ❤️

[@SaritaSingh-sd3yt]

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[@hussainbiology]

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[@manirulislam2704]

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[@ammaramehak9473]

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[@hussainbiology]

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[@dakshitasharma708]

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[@hussainbiology]

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[@04edwinmarshalc35]

Thank you bro

[@hussainbiology]

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[@sabasehar7049]

Nice video.

[@hussainbiology]

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[@shaharbanupp6975]

Tnq sir

[@nidhichhikara7658]

Sir ur videos are very good. It clears all the concept very well. But plss post the video in the interval of 1 day or max to max 2 days.... 1 week interval is very long.
Hope u will think upon this.

[@hussainbiology]

Hi Nidhi , it takes 3 or 4 days to get assemble information , then record it , and then editing...... All has to be done by single individual ☺️
Hope u understand the saturated schedule.

[@OdiaSongLyrics]

Are mrna and trna move or only ribosome moves?

[@hussainbiology]

Mostly it is the Ribosome that moves but mRNA also makes some shifts

[@biology_mcqs3037]

👍

[@tanu6464]

☺☺☺☺☺☺

[@misbahhussain1021]

How polypeptide chain gets released in the end

[@hussainbiology]

Shown

[@neetudagar6085]

If2GTP hydrolysis

[@sabasehar7049]

Sir where is next videos plzzzzzzz upload next video also.

[@hussainbiology]

InshaAllah next video today On Peptide bond formation and then from Next week we will start the Eukaryotic Translation in detail.

[@sabasehar7049]

Thanx for consideration.

[@hussainbiology]

@@sabasehar7049 keep sharing and supporting ✌️