Question

describe what causes the ribosome to release the protein. the ribosome reads a stop codon and a trna with an amino acid binds to the mrna. the ribosome reads a stop codon and a release factor binds to the mrna. the ribosome reads a start codon and a release factor binds to the mrna. the ribosome reads a start codon and a trna with an amino acid binds to the mrna.

Explanation:

To determine what causes the ribosome to release the protein, we analyze each option:

• Option 1: Stop codons do not have tRNAs with amino acids binding to them (tRNAs carry amino acids for coding codons, not stop codons), so this is incorrect.
• Option 2: During translation termination, when the ribosome reads a stop codon (UAA, UAG, UGA), a release factor binds to the A - site of the ribosome. This leads to the hydrolysis of the bond between the completed polypeptide (protein) and the tRNA in the P - site, causing the ribosome to release the protein. This is correct.
• Option 3: Start codons (like AUG) initiate translation, not terminate it, and release factors are involved in termination (not start), so this is incorrect.
• Option 4: Start codons initiate translation by having a tRNA with methionine (in eukaryotes) or formyl - methionine (in prokaryotes) bind, but this is for starting protein synthesis, not releasing the protein, so this is incorrect.

Answer:

The ribosome reads a stop codon and a release factor binds to the mRNA.