When we say a gene is expressing itself, what does "gene expression" mean in relation to protein synthesis?
There are thousands of genes in every human cell. Most of the genes in each human cell are the same. However, not all human cells produce the same proteins. In a multicellular organism like us, cells have particular functions because they have different proteins. Since different genes are expressed in different cell types, or through a process known as gene expression, they have different proteins.
Only the genes with the necessary protein codes are expressed by each type of cell. Hence, different cell types express different genes, allowing different proteins to be made. As a result, many cell types have various functions. A gene's protein product is typically produced once it has been expressed. Because of this, gene expression and protein synthesis are frequently seen as one process.