Health, disease and the development of medicines study guide

Monoclonal antibodies are highly specific antibodies produced in laboratories. They are designed to bind only to a particular antigen. This specificity makes them incredibly valuable in various medical applications. In pregnancy testing, they detect the hormone hCG, which is only present during pregnancy. For diagnosis, monoclonal antibodies can be engineered to attach to markers on cancer cells or blood clot components. When linked to a radioactive or fluorescent tag, they can then be used to locate these conditions within the body via imaging. In disease treatment, especially for cancer, monoclonal antibodies can deliver drugs or toxins directly to cancer cells, minimising harm to healthy tissues. They can also block signals that cancer cells need to grow or stimulate the immune system to attack them. This targeted approach is a significant advantage over conventional treatments like chemotherapy and radiotherapy, which often affect healthy cells alongside cancerous ones, leading to more severe side effects.

Viruses are obligate intracellular parasites, meaning they can only replicate inside living host cells. Their life cycle varies, primarily categorised into two main pathways: the lytic cycle and the lysogenic cycle. In both cycles, a virus must first attach to a host cell and inject its genetic material (DNA or RNA). In the lytic cycle, the viral genetic material takes over the host cell's machinery, causing it to produce new viral components. These components assemble into new virus particles, which then burst out of the host cell, destroying it. This bursting is called lysis. In contrast, the lysogenic cycle involves the integration of the viral genetic material into the host cell's genome. The host cell continues to live and reproduce normally, with the viral genetic material (now called a prophage in bacteria, or provirus in eukaryotes) being replicated along with the host cell's DNA. Under certain environmental triggers, the prophage can excise itself from the host genome and enter the lytic cycle, leading to the production of new viruses and host cell lysis. Some viruses, like bacteriophages, can switch between these two cycles.