Translation Mechanism in Ribosomes

Translation begins with the formation of an initiation complex, involving the smaller ribosomal subunit, the first amino acid tRNA, and mRNA. The larger ribosomal subunit joins, and initiation factors assist. The ribosome has P and A sites for tRNA binding. The process continues with elongation, where amino acids are added to the growing polypeptide chain. Termination occurs when a stop codon is reached, causing the ribosome to dissociate and release the mRNA and protein.

What components form the initiation complex in translation?

• Smaller ribosomal subunit, mRNA, and elongation factors

• tRNA, mRNA, and elongation factors

• Smaller ribosomal subunit, first amino acid tRNA, and mRNA

• Larger ribosomal subunit, mRNA, and initiation factors

Which ribosomal subunit joins the initiation complex after its formation?

• Smaller ribosomal subunit

• Larger ribosomal subunit

• Neither subunit

• Both subunits simultaneously

What are the two sites on the 70S ribosome where tRNA can bind?

• P site and A site

• P site and E site

• E site and A site

• A site and S site

Where does the initiating tRNA bind on the ribosome?

• A site

• E site

• P site

• S site

What happens to the amino acid carried by the tRNA in the P site?

• It is released from the ribosome

• It is joined to the amino acid in the A site

• It is transferred to the E site

• It is degraded

What occurs after the ribosome advances one codon?

• The first tRNA is released

• The ribosome dissociates

• The polypeptide chain is completed

• A stop codon is reached

What is the role of the ribosome during elongation?

• To initiate translation

• To add new amino acids to the polypeptide chain

• To terminate translation

• To dissociate into subunits

What signals the termination of polypeptide elongation?

• A stop codon

• A start codon

• A release factor

• A termination factor

What happens to the ribosome when a stop codon is reached?

• It dissociates into subunits

• It forms a new initiation complex

• It binds to another mRNA

• It continues translation

What is released along with the ribosomal subunits at the end of translation?

• Only the protein

• Only the mRNA

• Neither mRNA nor protein

• Both mRNA and protein