ABSTRACT
Gene expression The information stored in a cell’s DNA is used to make proteins in a process known as gene expression. In this process, DNA acts as a template for ribonucleic acid (RNA), which is produced by
transcription. In turn, RNA is translated into amino acids. Next, a chain of amino acids is joined together to produce peptides or polypeptides, which themselves may be joined together to produce proteins. (Note: The size boundaries distinguishing peptides, polypeptides, and proteins are arbitrary.) Finally, protein folding occurs,
during which a polypeptide or protein assumes its 3D, functional form (see Figure 2D.2). All cells in the body contain the same DNA; however, cells from different tissues clearly have very different functions. These differences occur because different genes are expressed in different types of cell, a process controlled by regulatory DNA sequences.
