Global challenges Study Guide

Genetic engineering is a powerful biotechnology technique that involves directly modifying an organism's genome. The genome is an organism's complete set of DNA, including all of its genes. In genetic engineering, specific genes are identified, isolated, and then transferred from one organism to another, or sometimes genes within the same organism are altered. The primary goal of this modification is to introduce desirable characteristics into the recipient organism that it did not previously possess or to enhance existing ones. For example, a gene for disease resistance from one plant species can be transferred into another crop plant to make the latter more resilient to pathogens. This process is distinct from traditional selective breeding, which relies on natural recombination and sexual reproduction. Genetic engineering allows for the transfer of genes between unrelated species, which would not be possible through conventional breeding. The steps typically involve identifying the desired gene, 'cutting' it out using enzymes, inserting it into a 'vector' (often a plasmid from bacteria or a virus) which acts as a carrier, and then introducing this vector into the cells of the target organism. Once inside the host cells, the new gene becomes part of the organism's own genetic material and can be expressed, leading to the desired trait. This technology has wide-ranging applications, including improving crop yields, developing new medicines like insulin, and creating organisms with enhanced metabolic capabilities.

Cancer is a disease characterised by the uncontrolled growth and division of cells. Normally, cells in the human body grow, divide, and die in a regulated manner, a process essential for development, tissue repair, and organ maintenance. This regulation is crucial to ensuring that tissues and organs function correctly. However, in cancer, this finely tuned process breaks down. Cells undergo changes, often due to mutations in their DNA, which disrupt the normal control mechanisms. These altered cells continuously divide without stopping, forming masses of tissue known as tumours. These tumours can be benign or malignant. Benign tumours are usually slow-growing and do not spread to other parts of the body, often staying localised. Malignant tumours, however, are more dangerous. They grow rapidly and have the ability to invade surrounding tissues and spread to distant sites through the bloodstream or lymphatic system in a process called metastasis. This spread to new locations leads to the formation of secondary tumours, making cancer much more difficult to treat and manage. Understanding these fundamental changes in cell behaviour is key to comprehending the nature of cancer as a disease of cell deregulation.