Biology Cheat Sheet

1. Detecting ‘self’ and ‘non self’ molecules: the role of antigens and the membrane receptors. Class I MHC molecules | Class II MHC molecules | * Are found on almost all nucleated cells of the body (so are not on red blood cells) * Body Cells that have become infected or become cancerous can display antigens by using their Class I MHC molecules on their cell surface * These antigens that get displayed were made inside these cells * Cytotoxic T cells will recognise antigens displayed in this way and will destroy infected cell | * Are only found on certain cells (usually B cells, macrophages and dendritic cells) * These cells are generally known as antigen presenting cells (APCs) * These antigens presented in this case were taken in and degraded by these cells (by endocytosis or phagocytosis) * The foreign material is broken down, and antigens displayed on the cell surface via Class II MHC molecules * Helper T cells recognise antigens displayed in this way |
The antigens, signal to other cells so they may either know what to look for or know to destroy the cells that these antigens are attached to.

2. Pathogens: AIDS/HIV Type | Caused by the Human Immunodeficiency Virus | Methods of control | Reverse transcriptase inhibitors: These drugs inhibit the ability of the virus to make copies of itselfProtease inhibitors (PIs): These medications interrupt virus replication at a later step in its life cycle, preventing cells from producing new viruses. | Transmission | Through the exchange of body fluids, blood, semen, vaginal fluids, saliva (sexual transmission, blood products) | How it causes disease in the host | The HIV virus infects The cells disabling the normal immune process | Symptoms | pneumonia caused by Pneumocystis, which causes wheezing; brain infection with toxoplasmosis which can cause trouble thinking or symptoms that mimic a stroke; widespread infection with a bacteria called MAC (mycobacterium avium complex) which