Which of the following processes involves the joining of amino acids in the correct order as directed by mRNA?

The process that involves the joining of amino acids in the correct order as directed by mRNA is translation. During translation, ribosomes read the sequence of nucleotides in the mRNA and translate it into a specific sequence of amino acids, forming a polypeptide chain. This sequence of amino acids then folds into a functional protein. The ribosome facilitates the matching of tRNA molecules, which carry specific amino acids, to the corresponding codons on the mRNA strand. This ensures that the amino acids are assembled in the correct order, which is critical for the protein's structure and function.

Transcription, on the other hand, is the process by which the genetic information in DNA is copied into mRNA, while replication is the process of copying DNA prior to cell division. Replication forks refer to the areas where the DNA is unwinding to allow replication to occur, rather than involving the assembly of amino acids. Thus, translation uniquely encompasses the synthesis of proteins, making it the correct answer in this context.