5.6 Steps of Translation Part 2 Flashcards
How does EF-G assist in translocation?
EF-G undergoes hydrolysis of GTP causing a conformational change that forces the small subunit to shift relative to the large subunit
How long does the growing amino acid chain have to be to be long enough to exit the tunnel in the large subunit?
about 30 amino acids long
What is the large and small subunit reponsible for during elongation of translation?
large = making the peptide bonds and pushing things along
small = recognition of codon sequences and matchmaking with mRNA
When does elongation of translation stop?
when the mRNA sequence encodes for a termination codon
What is a termination codon also known as?
stop or nonsense codon
What occurs when a termination codon appears on the mRNA during translation?
polypeptide is in the P site, A site is empty, and the termination codon recruits a release factor
What does a release factor do during translation?
binds to the A site and stimulates the hydrolysis of the peptide chain from the last tRNA and released it from the translational machinery
What does release factor 3 do?
binds to the ribosome to cause dissocation of the tRNA from the ribosome and stimulates the small and large subunits to dissociate
Can an mRNA assoicated with more than one ribosome?
yes; translation of a single mRNA can be happening at multiple sites known as polyribosomes or polysomes
Where does translation occur in eukaryotes and in prokaryotes?
both in the cytoplasm
What is a difference with transcription and translation in eukaryoes versus prokaryotes
eukaryotes that are spatially and temporally difference while in prokaryotes they are directly linked
What is the most significant difference in translation between eukaryotes and bacteria?
only three initiation factors are involved in bacteria but there are many more involved in eukaryotes
What is the initation factor that recognizes the start codon in eukaryotes?
tRNA i Met
Is there is a Shine-Delgarno sequence in eukaryotes?
no
What is the Kozak sequence?
sequence of bases upstream of the initiation codon that is thought to designate the presence of a start codon versus a methionine to be encoded within the context of a polypeptide
