1. Ribosomes move along mRNA in a 5′ to 3′ direction.
This statement is true. During the process of translation, ribosomes read the mRNA strand from the 5′ end to the 3′ end. This directional movement allows the ribosome to assemble amino acids into a polypeptide chain in the correct order as dictated by the genetic code.
2. All tRNA molecules enter the A site with the exception of the tRNA that transports methionine.
This statement is false. While the initiator tRNA, which carries methionine, does indeed bind directly to the P site of the ribosome during the initiation phase of translation, all subsequent tRNAs enter the A site. Therefore, not all tRNA molecules bypass the A site.
3. A nonsense mutation results in an amino acid being replaced by a stop codon.
This statement is true. A nonsense mutation occurs when a single nucleotide change results in a premature stop codon in the genetic code. This leads to the termination of protein synthesis before the full protein is formed, often resulting in a nonfunctional protein.
4. Mut…
This statement is incomplete. Without additional context or information, it is not possible to determine the truth value of the statement. If you have a specific mutation in mind, please provide those details for a comprehensive answer.