Biology MYA Practice Test 2026 - Free Biology Practice Questions and Study Guide

Protein synthesis from amino acids happens at the ribosome, the molecular machine that carries out translation. It reads the message carried by mRNA and uses transfer RNAs to bring in the correct amino acids, forming peptide bonds that link them into a growing polypeptide chain. The nucleus stores DNA and is where transcription occurs, not where proteins are built. Mitochondria do have their own ribosomes and synthesize some proteins, but this is a limited subset and not the general process of assembling proteins from amino acids. The Golgi apparatus modifies and sorts proteins after they’re made, not the initial assembly. So the ribosome is the place where amino acids are joined to build proteins.