What are the three functional groups of the M HC genes

What are the three functional groups of the M HC genes

The correct answer and explanation is:

The three functional groups of the Major Histocompatibility Complex (MHC) genes are:

1. Class I MHC genes
2. Class II MHC genes
3. Class III MHC genes

Explanation (300 words):

The Major Histocompatibility Complex (MHC) is a group of genes essential for immune system function, particularly in antigen presentation and immune recognition. These genes are located on chromosome 6 in humans and are categorized into three functional classes based on their structure and role in immunity.

1. Class I MHC genes encode glycoproteins found on the surface of almost all nucleated cells. Their main function is to present endogenous antigens (such as viral or tumor peptides) to cytotoxic CD8+ T cells. This allows the immune system to detect and destroy infected or cancerous cells. The key genes in this group include HLA-A, HLA-B, and HLA-C. Each person inherits one set of these genes from each parent, contributing to the diversity of immune responses.
2. Class II MHC genes encode molecules expressed primarily on antigen-presenting cells (APCs), such as dendritic cells, macrophages, and B cells. These molecules present exogenous antigens (like bacterial proteins) to helper CD4+ T cells, initiating the immune response. The key genes include HLA-DP, HLA-DQ, and HLA-DR. These proteins are crucial for coordinating immune responses and developing immunological memory.
3. Class III MHC genes do not play a direct role in antigen presentation but encode various other immune-related proteins. These include complement proteins (like C2, C4, and factor B) and inflammatory cytokines (such as TNF-α). Though structurally and functionally different from Class I and II, they are located within the same chromosomal region and support broader immune functions.

In summary, the MHC genes are central to immune recognition. Class I and II genes help present antigens to T cells, while Class III genes contribute to the immune response through other proteins like cytokines and complement components.