What are proteins that have carbohydrates covalently bonded to them called?

Proteins that have carbohydrates covalently bonded to them are referred to as glycoproteins. This designation arises from the structural modification of proteins where one or more oligosaccharide chains are attached, influencing various functions such as cell signaling, immune responses, and cell recognition. Glycoproteins play critical roles in processes like the formation of the extracellular matrix, mediating cell-to-cell interactions, and acting as receptors in signaling pathways.

In contrast, enzymes specifically refer to proteins that catalyze biochemical reactions, while hormones are signaling molecules that regulate physiological processes in the body. Cholesterol is a type of lipid that is essential for membrane structure and fluidity, not a protein. Hence, the term glycoproteins accurately captures the essence of proteins that have carbohydrates attached, defining their structure and functional significance in biological systems.