how does the biological clock tick

The biological clock ticks as an internal genetic mechanism that measures and controls the aging process of organisms. This clock regulates the lifespan, which is genetically determined and related to metabolic rate and body mass. Essentially, living organisms are dynamic systems continuously renewing their materials, maintaining a balance between destruction of old material and formation of new material. This internal clock ultimately determines the lifespan and timing of death as the final step in a fixed biological program. Larger organisms generally have lower metabolic rates and longer lifespans, and those that conserve energy tend to live longer. The biological clock thus functions through metabolic and genetic factors that govern aging and life duration.