Final answer:
The assertion that MHC class I molecules bind to small peptides and class II to long glycolipids is false. Both MHC classes bind peptides; class I is on all nucleated cells with intracellular peptides, and class II is on professional antigen-presenting cells with extracellular peptides.
Step-by-step explanation:
The statement that MHC class I molecules bind to small peptides, while class II bind to long glycolipids is false. Both MHC class I and class II molecules bind peptides, not glycolipids. MHC class I molecules present peptides derived from intracellular proteins and are found on all nucleated cells. They form a complex with β₂-microglobulin and the peptide-binding groove is formed by a1 and a2 domains. On the other hand, MHC class II molecules present peptides derived from extracellular proteins and are primarily found on professional antigen-presenting cells like macrophages, dendritic cells, and B cells. The peptide-binding groove of MHC class II is formed by the a1 and β1 domains. Therefore, it's essential to understand that the primary difference between MHC class I and II molecules is the source of peptides they present and their cellular distribution, not the type of molecule (peptide vs. glycolipid) they bind to.