AP BIOLOGY

Detailed explanation-1: -Human leukocyte antigens (HLA) are a group of identification molecules located on the surface of all cells in a combination that is almost unique for each person, thereby enabling the body to distinguish self from nonself. This group of identification molecules is also called the major histocompatibility complex.

Detailed explanation-2: -major histocompatibility complex (MHC), group of genes that code for proteins found on the surfaces of cells that help the immune system recognize foreign substances. MHC proteins are found in all higher vertebrates. In human beings the complex is also called the human leukocyte antigen (HLA) system.

Detailed explanation-3: -The function of MHC molecules is to bind peptide fragments derived from pathogens and display them on the cell surface for recognition by the appropriate T cells.

Detailed explanation-4: -MHC class I or major histocompatibility complex type 1 is a diverse set of cell surface receptors expressed on all nucleated cells in the body, as well as platelets. In humans, MHC also has the name HLA (human leukocyte antigen), and these are three subtypes, HLA-A, HLA-B, and HLA-C.

Detailed explanation-5: -Antigens are substances (usually proteins) on the surface of cells, viruses, fungi, or bacteria. Nonliving substances such as toxins, chemicals, drugs, and foreign particles (such as a splinter) can also be antigens. The immune system recognizes and destroys, or tries to destroy, substances that contain antigens.