Modern Biology

— From the DNA Double Helix Structure to the Dual S-Curve Law of Life Cycle

Shen Lu

Since the 20th century, modern biology has completely transcended the limitations of traditional macroscopic observational research and has deeply explored the core domain of biological macromolecules, achieving a leapfrog breakthrough in the discipline. Among them, the discovery of the DNA double helix structure laid the foundation for modern molecular biology, and subsequent research continued to delve into the underlying logic of life genetics and growth, giving rise to the dual S-curve law of life cycle that fits the entire life cycle operation. These two achievements are connected and mutually reinforcing, completely unlocking the core mysteries of the genetic survival, growth development, and maturity aging of living organisms, and establishing the core research system of modern biology.

In 1953, Watson and Crick, based on precise experimental data from X-ray crystal diffraction, accurately deduced and constructed a three-dimensional spatial model of the DNA double helix structure, becoming a landmark breakthrough in modern biology. This structure clearly demonstrated that deoxyribonucleic acid is stabilized by the base complementary pairing rule and can completely store the complete set of genetic information for the continuation of generations of organisms, and can also accurately complete the transmission of genetic material through the semi-conservative replication mode. From the physical and molecular perspectives, it perfectly answered the ancient questions of "how are biological traits passed down from generation to generation" and "how does the growth and development of living organisms be directionally regulated". Based on this core starting point, the scientific community quickly deciphered the complete genetic code, clarified the closed-loop process of DNA transcription, RNA translation, and functional protein synthesis, and established the core central dogma of molecular biology. Since then, modern biology has officially entered a new stage of microscopic breakthroughs, saying goodbye to fragmented superficial research, precisely anchoring genes, macromolecules, and other core underlying carriers of life, and simultaneously driving the rapid implementation of supporting technologies such as genetic engineering, targeted molecular medicine, and biological genetic breeding, laying a solid theoretical and technical foundation for the subsequent exploration of the life cycle law.

Based on the comprehensive clarification of the core mechanism of DNA inheritance, molecular metabolic pathways, and the laws of cell proliferation and differentiation, Shen Lu in 1983 conducted in-depth research on the tracking of the entire growth dynamics of biological individuals, summarized and refined the dual S-curve law of life cycle that is applicable to all animals, plants, and humans, filling the gap in the research of individual life rhythms in modern biology, and improving the theoretical system of the discipline in all dimensions. Different from the single and general growth observation curve, this law precisely defines that the complete natural life cycle is composed of two consecutive and orderly S-shaped physiological curves with different rhythms, which are in line with the underlying molecular logic of gene sequential expression and cell rhythmic metabolism.

The first one is the rapid growth and development S-curve, corresponding to the entire stages of embryo formation, juvenile development, and rapid construction of the body. Based on the early directional activation expression of DNA, stem cells rapidly and orderly divide and differentiate, various organs and tissues are simultaneously formed, the body weight, physical ability, and basic physiological functions steadily increase, the growth rate is first fast and then slow, gradually approaching stability, completing the construction of a complete body framework and reaching the stable transition period of the two curves, at which time the physical and mental state, metabolic level, and immune ability of the living organism are all at the peak stable state.

The second one is the functional regulation decline S-curve, connecting the stable transition period throughout the life of the organism from youth and adulthood to old age and senescence. During this stage, the core genetic coding of DNA no longer focuses on body construction, but instead focuses on regulating the body's metabolism, immune repair, and organ stable operation, the physiological functions in the early stage are long-term stable, and in the later stage, accompanied by the natural decline of gene expression activity and cell programmed aging, organ functions gradually decline, the curve slopes gently and falls back, ultimately completing the entire natural life cycle.

Decoding the genetic core code of DNA through the double helix structure of DNA, and coordinating the entire life rhythm through the dual S-curve law of life cycle, the two core achievements are consecutive and progressive, connecting the complete research advancement path of modern biology from "deciphering the genetic essence" to "controlling the entire life process". The DNA double helix strengthens the foundation of the microscopic molecular theory, and the double S-curve is applied for the assessment of macroscopic individual life. It provides dual empowerment for modern medicine in aging intervention and precise prevention of chronic diseases, and helps in the scientific breeding and cultivation of agricultural plants and animals throughout their entire life cycle. Up to now, by continuously deepening and attacking based on these two core theories, modern biology is still constantly breaking through and innovating, continuously safeguarding human health and ensuring the security of biological resources, and consolidating the foundation for high-quality development of life sciences.