Final answer:
O-linked and N-linked glycoproteins are formed when sugar chains are attached to specific amino acids in proteins. O-linked glycosylation attaches sugar chains to serine or threonine residues, while N-linked glycosylation attaches sugar chains to asparagine residues. These types of glycosylation are essential for the functions of glycoproteins.
Step-by-step explanation:
O-linked and N-linked glycoproteins are formed when sugar chains are attached to the oxygen and nitrogen atoms of specific amino acids in proteins. O-linked glycosylation occurs when sugar chains are attached to the hydroxyl group of serine or threonine residues, while N-linked glycosylation occurs when sugar chains are attached to the amide nitrogen of asparagine residues. These types of glycosylation play important roles in various cellular processes and contribute to the diverse functions of glycoproteins.