MBB 222 Study Guide - Final Guide: Stop Codon, Release Factor, Transfer Rna

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browncricket987

20 Dec 2018

School

Simon Fraser University

Department

Molec Biol & Biochem

Course

MBB 222

Professor

Adam Barlev

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Document Summary

The peptidyl-trna is in the p site, and the a site is empty and ready for the next aa trnaaa. Tu and ef-g overlap, so only one of these proteins can be bound to the ribosome at any given time. Release factors bind to the termination codon and lead to release of the polypeptide chain. Binding of the associated release factor protein (release factor 2; rf2) to the stop codon in the mrna leads to gtp hydrolysis and release of all bound translational components. Hydrolysis of the terminal peptidyl-trna bond (the growing polypeptide transfers from trna to a water molecule rather than a new aa) release of the last uncharged trna and the polypeptide. Dissociation of the 70s ribosome into the 30s and 50s subunits. Ran-dependent import/export the nuclear pore complex regulates what can leave and enter the nucleus. Ran-dependent nuclear import and export of protein and rna cargo is mediated by importin and exportin proteins.

Related Questions

What happens when a stop codon is reached by a ribosome?

A termination tRNA^ter binds to the codon and the growing peptide is transferred to it. When the peptidyl-tRNA^terreaches the P site, the ribosome is signaled to release the protein. The ribosome then is likely to dissociate.

A release factor binds to the codon and is used to release the growing peptide from the P site tRNA.

A termination tRNA^ter binds to the codon and the growing peptide is transferred to it. When the peptidyl-tRNA^terreaches the P site, the ribosome dissociates. A separate peptidyl transferase then releases the protein from tRNA^ter.

A release factor binds to the codon and the ribosome dissociates. A separate peptidyl transferase then releases the protein from the last tRNA to which was attached.

A termination tRNA^ter binds to the codon and is used to release the growing peptide from the P site tRNA. The ribosome then is likely to dissociate.

coffeeyellowjacket278

Hi guys, could you help me on this question?

Facts about ribosomes

Indicate whether each of the following statements aboutribosomes is true or false.

1. Ribosomes are composed of tRNA and protein. TrueFalse
2. During translation in eukaryotes, some ribosomes remain free inthe cytoplasm while others attach to protein channels embedded inthe RER. TrueFalse
3. During initiation of translation, the small ribosomal subunitjoins to the mRNA and initiator rRNA, followed by the largeribosomal subunit. TrueFalse
4. When a ribosome first assembles on the mRNA, the initiator tRNAoccupies the A site while the P and E sites are empty.TrueFalse
5. During translation, a charged tRNA first binds to the ribosomeif its anticodon matches the codon in the E site. TrueFalse
6. A peptide bond forms between the amino acid attached to a tRNAin the A site and the growing polypeptide attached to a tRNA in theP site. TrueFalse
7. Uncharged tRNA molecules in the E site are ejected from theribosome. TrueFalse
8. No more than 2 tRNA molecules are bound to a ribosome at anygiven time. TrueFalse
9. During translocation of the ribosome, tRNA molecules move fromthe P site, to the A site, to the E site, and are then ejected fromthe ribosome. TrueFalse
10. During translation, an amino acid attached to a tRNA in the Asite is transferred to a growing polypeptide attached to a tRNA inthe P site. TrueFalse

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MBB 222 Study Guide - Final Guide: Stop Codon, Release Factor, Transfer Rna

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