Mutational effects

Abstract

Mutagens are agents that cause permanent genetic changes (i.e., mutations). These mutations can be limited to a single cell or may become part of an entire population of organisms. Chemicals as well radiation can cause mutations. Mutagens can be divided into direct and indirect acting mutagens. Direct acting chemical mutagens are often electrophilic and chemically reactive. Indirect acting chemical mutagens often require metabolic activation. Some agents (e.g., ionizing radiation) can act as both. Radiation induced mutational damage is related to the size and speed of the particles with larger particles causing more damage but having less penetrating power. Mutations can be limited to a single base or can involve multiple chromosomes. Mutations can occur in coding and non-coding regions of the genome. Mutations in the coding regions of the genome range in severity from generally harmless silent mutations to lethal vital protein destroying mutations. Mutations in the non-coding regions can sometimes cause functional changes (e.g., splice enhancer mutations). The earlier during development a mutation occurs the greater the potential for it to spread and impact the entire organism. Mutations that occur in the germ cells can be passed on to future generations and are of the greatest concern. Mutation frequencies differ depending on the bases being substituted and the mutagens involved. Translational toxicology includes efforts to limit exposures to potent chemical mutagens (e.g., aflatoxin) and mutagenic radiation (e.g., radon gas, UV light).