Mini Review Volume 1 Issue 4 - February 2017 Curr Trends Biomedical Eng & Biosci Copyright © All rights are reserved by Gheorghe Maria Application of (bio) chemical engineering principles and lumping analysis in modelling the living systems Gheorghe Maria* Department of Chemical & Biochemical Engineering, University Politehnica of Bucharest, Romania Submission: February 07, 2017; Published: February 10, 2017 *Corresponding author: Gheorghe Maria, Department of Chemical & Biochemical Engineering, Politehnica University of Bucharest, Splaiul Independenței 313, București 060042, Romania, Email: Introduction Living cells are organized, self-replicating, self-adjustable, evolvable and responsive structures to environmental stimuli. Attempts to model metabolic cell reactions and processes are not new, an adequate dynamic model being the one engineering alternative to coherently, consistently, and systematically in- silico represent the cell metabolism aiming at studying the cell response to various perturbations (reviews [5,6,8,17,18]). Thus, Synthetic Biology and System Biology become emergent sciences focus on the engineering-driven model-based building of complex biological entities, aiming at applying engineering principles of systems design to biology with the idea to produce predictable and robust biological systems with novel functions in a broad area of applications, such as therapy of diseases (gene therapy), design of new biotechnological processes, new devices based on cell-cell communicators, biosensors, etc. “System Biology can be defined as “the science of discovering, modelling, understanding and ultimately engineering at the molecular level the dynamic relationships between the biological molecules that define living organisms.” (Leroy Hood, President Institute for System Biology, Seattle, USA, cited by [17,18]). Due to the highly complex and partly unknown aspects of the metabolic processes, the detailed mathematical modelling at a molecular level remains still an unsettled issue, even if remarkable progresses and developments of extended simulation platforms have been reported. The general modelling rules, based on physico-chemical-biological and chemical engineering principles, and a statistical data treatment are more difficult to be applied to living systems. That is because metabolic cell processes present a low observability vs. the very large number of species of the order O(10 4 ), reactions O(10 5 ), Current Trends in Biomedical Engineering & Biosciences Curr Trends Biomedical Eng & Biosci 1(4): CTBEB.MS.ID.555566 (2017) 001 Abstract The ”whole-cell” simulation of cell metabolic processes under considering a variable-volume modelling framework has been reviewed to prove their advantages when building-up modular model structures of simplified form that can reproduce complex protein syntheses inside cells. The more realistic “whole-cell-variable-volume” (VVWC) approach is reviewed when developing modular kinetic representations of the homeostatic gene expression regulatory modules (GERM) that control the protein synthesis and homeostasis of metabolic processes. The paper review the general concepts of the VVWC modelling, while the cited literature includes past and current experience with GERM linking rules in order to point-out how optimized globally efficient kinetic models for the genetic regulatory circuits (GRC) can be obtained to reproduce experimental observations. Based on quantitative regulatory indices evaluated vs. simulated dynamic and stationary environmental perturbations, the reviewed literature exemplifies with GERM -s from E. coil, at a generic level, how this methodology can be extended: i) To characterize the module efficiency, species connectivity, and system stability; ii) To build-up modular regulatory chains of various complexity; iii)To prove feasibility of the cooperative vs. concurrent construction that ensures an efficient gene expression, system homeostasis, proteic functions, and a balanced cell growth during the cell cycle; iv) To prove the effect of the whole-cell content ballast in smoothing the effect of internal/external perturbations on the system homeostasis. Keywords: Kinetic modelling of cell metabolic processes; Homeostatic regulation of gene expression; Regulatory modules of gene expression (GERM); Linking GERM-s