In protein synthesis, DNA instructs the creation of protein. But since DNA does not directly make the proteins, it needs RNA to produce proteins. This is where the gene expression takes place. It is the process through which information encoded in a gene is used to create either RNA molecules that code for proteins or non-coding RNA molecules that fulfill other functions. A gene’s DNA is used as a template for synthesis of a specific protein. Since different genes are expressed in different cell types, they have distinct proteins.
Reference:
Protein Synthesis. (2022, March 27). Retrieved from https://www.ck12.org/c/life-science/protein-synthesis/lesson/Protein-Synthesis-and-Gene-Expression-MS-LS/