During which phase does the information in mRNA direct the building of proteins?

The correct answer is that during translation, the information encoded in messenger RNA (mRNA) directs the synthesis of proteins. This process takes place in the ribosome, where the sequence of nucleotides in mRNA is read in sets of three, known as codons. Each codon corresponds to a specific amino acid, which are the building blocks of proteins.

During translation, transfer RNA (tRNA) molecules transport the appropriate amino acids to the ribosome, where they are added to the growing polypeptide chain in the order specified by the mRNA. Once the entire mRNA strand has been read and the corresponding amino acids have been linked together, the polypeptide chain folds into a functional protein.

Transcription, on the other hand, is the process by which DNA is copied into RNA, specifically mRNA, but does not involve the assembly of proteins. Replication is related to DNA copying itself, and modification typically refers to post-transcriptional processes such as RNA splicing, which occur before mRNA translation, not during the actual protein synthesis. This understanding highlights the distinct roles of each stage in the central dogma of molecular biology, where translation specifically refers to the synthesis of proteins from mRNA.