Final answer:
Gene expression is a process that includes transcription, where DNA is used to create mRNA, followed by translation, where mRNA directs the assembly of amino acids into a protein.
Step-by-step explanation:
The expression of a gene is a multistep process. During transcription, one of the DNA strands is used as a template to make an RNA strand. During translation, the RNA strand is used to specify the sequence of amino acids within a polypeptide.
Transcription begins with a region of DNA unwinding, where RNA polymerase synthesizes a strand of mRNA that is complementary to the gene of interest. This mRNA serves as a transcript, or copy, of the gene's DNA code. The process includes three stages: initiation, where the unwinding begins; elongation, where a sequence of mRNA is elongated; and termination, where the process ends and the mRNA is released.
Translation is the subsequent process where the mRNA is used by the ribosome to synthesize a protein with a specific sequence of amino acids, encoded by the gene. Ribosomes read the mRNA codons, each codon specifying one amino acid, and assemble the polypeptide chain accordingly. This is how the genetic code is expressed as a functional protein.