Proteins and lipids are modified into glycoproteins and glycolipids primarily by the Golgi complex (also known as the Golgi apparatus or Golgi body).

The Golgi complex is involved in post-translational modification of proteins and lipids, including the addition of carbohydrate chains to proteins (glycoproteins) and lipids (glycolipids), which are important for various cellular functions, including cell-cell recognition and signaling. Rough endoplasmic reticulum (Option B) is involved in protein synthesis and initial protein folding, while smooth endoplasmic reticulum (Option C) plays a role in lipid metabolism and detoxification. Ribosomes and chromosomes (Option D) are not directly involved in the modification of proteins and lipids into glycoproteins and glycolipids.