Messenger RNA/Translation initiation Flashcards
True/False, do all of the base sequences contain information in mRNA?
False
There is information in the base sequence of an mRNA, but not all of the base sequences contain information
What are untranslated regions (UTRs)?
They are base sequences near the two ends of the strand that do not contain information
What are the roles of UTRs in translation?
They have roles in starting and stopping the process of translation
what are the beginning of the mRNA and the end of the mRNA called?
Beginning: 5’ UTR
End: 3’ UTR
Where does the coding sequence lie?
In between the 5’ and 3’ UTRs
What is the special structure of eukaryotic mRNAs?
cap
Where is a cap added to?
A cap is added to the 5’ end of an mRNA after transcription, but before the mRNA is transported from the nucleus to the cytoplasm
What is the process called when adding a cap to an mRNA? What is the nucleotide that is added?
Adding a cap to an mRNA is called “capping”
The nucleotide 7-methylguanosine monophosphate is added during capping
In eukaryotic cells, initiation needs what?
Initiation in eukaryotic cells requires the activity of eukaryotic initiation factors (eIFs)
Which eIFs bind to the small subunit and prevent attachment to the large subunit?
eIF1
eIF3
eIF6
What does eIF4 do?
It binds to the 5’ cap of an mRNA and promotes the binding of the mRNA to the small subunit of the ribosome
What is AUG? What does this mean when you find that there is another AUG?
AUG is the first codon in the mRNA and is called the start codon
Any other AUG found after the start codon encodes methionine, not another start codon
What are the base sequences that lie before the start codon? What about after?
Before the start codon: 5’ UTR
After the start codon: 3’ UTR
What is the initiator tRNA?
A special aminoacyl-tRNA that pairs ONLY with the start codon (not methionine)
It is a methionyl-tRNA
What does eIF2 help do in initiation?
It binds the initiator tRNA to the start codon
