Answer: Protein molecules are made through the transcription of a DNA strand into an mRNA strand and the translation of the mRNA into a protein. Transcription takes place in the nucleus of the cell while translation takes place in the ribosome.
Explanation: Transcription is a process of copying the genetic message encoded in a DNA strand into a messenger RNA (mRNA). This process is the first step in protein synthesis and takes place in the nucleus. It is catalyzed by an enzyme known as RNA polymerase. The synthesized mRNA then leaves the nucleus and enters the ribosome where translation occurs. During translation, the mRNA passes through the ribosome complex three nucleotides at a time where the codon is read and the corresponding amino acid coded for is fetched and attached to the peptide chain by the transfer RNA (tRNA). Translation starts when the ribosome encounters the start or initiation codon on the mRNA molecule. The start codon is AUG and it codes for methionine. Translation stops when the ribosome encounters the stop or termination codon. There are three termination codons and they are so named because they do not code for any known amino acid. The termination codons are UAG, UAA and UGA.