Global challenges Study Guide

Diseases are conditions that impair the normal functioning of a living organism. They can be broadly classified into two main categories: communicable and non-communicable diseases. Communicable diseases, also known as infectious diseases, are caused by pathogens such as bacteria, viruses, fungi, or protists. These diseases can be transmitted from one person to another, or from animals to humans, through various means like direct contact, airborne particles, contaminated food or water, or insect vectors. Examples include the flu, measles, COVID-19, and malaria. Control measures often involve vaccination, hygiene improvements, isolation of infected individuals, and antibiotic or antiviral treatments. Non-communicable diseases (NCDs), also known as non-infectious or chronic diseases, are not caused by pathogens and cannot be spread from one person to another. They often result from a combination of genetic, lifestyle, and environmental factors. Examples include heart disease, cancer, diabetes, and asthma. Many NCDs develop slowly over time and can be influenced by diet, exercise, smoking, and alcohol consumption. Prevention often focuses on promoting healthy lifestyles and early detection through screening. Understanding the differences between these disease types is crucial for effective prevention, diagnosis, and treatment strategies, impacting public health policies and individual well-being.

Genetic engineering is a powerful set of techniques that allows scientists to transfer individual genes from one organism to another, even between different species. This process enables the modification of an organism's characteristics or the production of useful substances. The steps involved are precise and require careful execution. Initially, the desired gene must be identified and isolated from the donor organism's DNA. This isolation often involves using specific enzymes, called restriction enzymes, which act like molecular scissors to cut the DNA at particular recognition sequences, effectively 'cutting out' the gene of interest. Next, a vector is needed to carry this isolated gene into the recipient organism. Plasmids, small, circular pieces of DNA found in bacteria, are commonly used as vectors because they can be easily manipulated and readily taken up by bacterial cells. The isolated gene is then inserted into the plasmid. This insertion is also facilitated by enzymes; the same restriction enzyme that cut out the gene is often used to cut open the plasmid, creating complementary 'sticky ends'. An enzyme called DNA ligase then 'pastes' the gene into the opened plasmid, forming a recombinant plasmid. This recombinant plasmid, which now contains the foreign gene, is then introduced into the recipient organism, typically a bacterium. This process, known as transformation, involves making the bacterial cells permeable so they can take up the plasmid. Once inside the recipient cell, the recombinant plasmid can replicate independently and, crucially, the newly introduced gene can be expressed. This means the recipient organism will start producing the protein or characteristic encoded by the transferred gene. For example, bacteria can be engineered to produce human insulin, which is vital for treating diabetes. The final steps involve selecting and culturing the transformed cells, allowing them to multiply and produce the desired product or characteristic. This technology has wide-ranging applications in medicine, agriculture, and industry.