The document summarizes the two main processes of protein synthesis: transcription and translation. During transcription, RNA polymerase in the nucleus copies DNA into a messenger RNA strand. During translation, the mRNA strand exits the nucleus and attaches to a ribosome in the cytoplasm. The ribosome then reads the mRNA codons and links amino acids together to form a polypeptide chain according to the mRNA sequence. This polypeptide chain will later fold into the final protein structure.