Translation Flashcards
What initiates translation
when the mature mRNA is exported from the nucleus to the cytoplasm
Reading Frame
Defines the amino acid sequence and is read from the 5’ end AUG
What is the link between mRNA and protein
tRNA
Where will the amino acid connect to on the tRNA
It will attach to the 3’ end
Anticodon
Binds to mRNA and its antiparallel and complementary
The anti codon is 5’-3’, corresponding codon is 3-5
Ensures that the current amino acid is paired with the correct polypeptide chain
How is the redundancy managed for translation
- More than 1 tRNA for multiple amino acids
- Some tRNA can recognize and bind to codon
How do we ensure Fidelity
Aminacyl-tRNA synthetase which places correct amino acid sequence
how is tRNA recognized by synthetase
1.Identifying the anticodon
2. Recognizing the acceptor arm
3. Reading 3’ and placing correct amino acid
Where is the ribosomal structure located
In the endoplasmic reticulum on cytoplasm
What is the ribosomal structure
Large subunit: E,P, A site
Small subunit: mRNA binding site
What are the functions of the EPA site
E site: exit site where tRNA leaves
P site: peptide site where the growing polypeptide site
A site: aminoacyl site which places the next amino acid on tRNA
Elongation and Quality Control of Translation
EF-TU (P) and EF1 checks the A site to make sure that the correct AA has been placed.
If it is not correct, the EF1 will not release
If it is correct, GTP will hydrolysis and EF1 will release
What is the other elongation factor
EF-G or EF2 helps ribosome move more efficiently
What are the functions of elongation function
Efficiency and error correcting
EF-TU and EFG
EF-TU: binds to aminoacyl acid
EFG: helps ribosome move along
What is the initiation process of translation
- Shine-Dalgarno sequences bind to small subunit
- Positioning of small subunit on the initiating codon requires initiator factors
3.Fmethionine aminoacyl tRNA binds to start codon - Large subunit binds
Initiation of Translation (E)
- EIF4E eukaryotic initiator fact binds to the 5’ cap
- EIF4G circulates the mRNA and also binds to EIF4E
- Translation initiation factor and METinitiator tRNA bind to small subunit
- The unit moves along to the AUG codon and large subunit attaches and initiation factors dissociate and translation can proceed
Translation termination
Human releasing translation factor is a protein
Post translation modification
Phosphorylation and glycosylation
Why would covalent modifications be required
To make protein active
To move protein to proper organelle
How is protein degradation controlled
Every protein has a small ubiquitin covalently attached to it which directs them to proteasome and they will degraded by proteases
