11: Prokaryotic Transcription & Translation Flashcards
What genes are organized into operons?
Some prokaryotic genes
What is the effect of greater RBS strength in an operon?
Producing more protein despite an equal amount of mRNA
Can transcription stop at a stop codon?
No, it can only stop at a TX terminator
Can translation of a protein be affected by a different gene’s RBS?
No
What are the three phases of translation?
Initiation, elongation, and termination
Are tRNAs transcribed from DNA?
Yes
Do tRNAs encode amino acid sequences?
No, so they are not translated
What carries amino acids to the ribosome?
tRNA
What part of tRNA binds to mRNA?
Anticodons in tRNA bind to complementary codons of mRNA.
What adds amino acids to tRNAs?
Aminoacyl-tRNA synthatases
How many aminoacyl-tRNA synthetases are there?
20 - one for each amino acid
Do aminoacyl-tRNA synthetases use the anti-codon to recognize their tRNAs?
No, they bind the acceptor stem of the tRNA
Do different tRNAs for the same amino acid have similar or different acceptor stems?
Similar
How can some tRNAs read multiple codons?
They wobble at the third position
What two things are required for prokaryotic TL initiation?
An intiator factor and a special initiator tRNA
What terminates translation by recognizing stop codons?
Release factors that enter the A pocket and bind a stop codon.
Is the RBS transcribed?
Yes
Could loss-of-function point mutations in an RBS theoretically be suppressed by point mutations in the 16S rRNA?
Yes because of the complementarity between the RBS and the 16S rRNA
In what stage of translation is the finished polypeptide released to go and do its job in the cell?
Termination
In what stage of translation does the ribosome gets together with the mRNA and the first tRNA so translation can begin?
Initiation
In what stage of translation are amino acids brought to the ribosome by tRNAs and linked together to form a chain
Elongation
What transfers the polypeptide from the tRNA in the P site to the new amino acid attached to the tRNA in the A site?
The peptidyltransferase activity of the ribosome
How is tRNA along with the attached polypeptide translocated from the A site back to the P site?
With EF-G and GTP
