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Flashcards in Protein synthesis 2 eukaryotes Deck (10)
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What is required for the small part of the ribosome (40s) to bind to the mRNA?

A binding site at the level of the cap, and presence of cap-binding proteins.


While the 40s is moving along the untranslated region of the mRNA to the first AUG, what powers such movement?

ATP powered helicases


What is the Kozak sequence?

a sequence right before the first codon, ending with AUG. Provides context for translation initiation


Once the 40s subunit has found the first AUG and bound the first tRNA, what happens?

The initiation factors dissociate, allowing the large subunit (60s) to associate to it.


Define EF-Tu

An elongation factor that is bound to a new tRNA to the A site. It temporarily prevents the peptidyl reaction to ensure correct pairing to the codon.


Define EF-G

It binds the large subunit of the A-site and moves it up next to the 40s unit that has just shifted over one codon.


What is the role of the release factor?

Bind to the A-site of the ribosome, and cause the last amino acid in the polypeptide to bind to water, getting rid of the reactive OH group.


What is the role of the ribosome recycling factor

replaces the RF in the A site and causes the ribosome to dissociate by attracting EF-G.


Define translation recoding in the context of selenocysteine.

Selenocysteine is linked to a tRNA that has a stop codon as its anticodon. it will bind when that stop codon is reached, and the mRNA downstream will form a "stem and loop" that allows a specific translation factor to allows this AA to be incorporated.


What is transtional shift, a special case?

An occasional slip of the ribosome will allow passage of a stop codon, allowing for a different protein to be made from the same strand of mRNA.