An Introduction to Engineering in Synthetic Biology

Synthetic biology is often described as an approach which uses engineering principles to develop biological systems, and therefore the engineering of a biological system (often a bacterial organism) is the central goal of any iGEM project. But what does this actually mean, and how can it be achieved? Here, on the engineering hub, information is provided on what engineering is, and how to best approach the challenge of engineering biological systems such that they perform as desired.

What is Engineering?

In typical engineering fields, such as electrical, software, and mechanical engineering, a set of principles are used to design and build things. These principles help ensure that the end product meets the initial expectations, and that the development process is efficient (in terms of money, time, and resources used). This process is explained below using the example of building an aircraft, which is very expensive and costly and can have very serious consequences if not done properly.

The Engineering Process

The first stage of building an aeroplane is to define the design constraints and specification. This essentially describes what the aircraft should, and should not, do and is critical to ensure that the final product is fit for purpose. For example, if building a helicopter, the aircraft should be able to take off vertically, but this isn’t necessary for an aeroplane. The next stage is to design a prototype for the aircraft which meets the specifications. Once a prototype has been designed, it needs to be tested. Unfortunately, it isn’t feasible to just build the aircraft and then see if it flies. Instead, the prototype is modelled and simulated in various ways to see whether it functions correctly. Based on model data, the prototype is then adjusted until it meets the specifications. Following this, a plan for how to build the prototype is made. The build plan usually makes heavy use of standard components from previous aircraft which are known to work. Usually, the prototype is built in stages to test each part separately as this is less expensive than building an entire aircraft which may not function correctly. Once the prototype (or part of the prototype) is built, it is tested. This test data is then compared to the models/simulations and the specifications, and if necessary, the initial design is modified. The process of modelling/simulating, building, and testing the new design is then performed again. This process is repeated until the aircraft prototype meets the specifications.


The process described above of designing, building, testing, and then learning from the data collected is known as the Engineering Cycle.

The Engineering Cycle

Like other engineering fields, engineering a biological system is a complex, challenging, and often slow process, and can be described as an engineering cycle consisting of the four stages shown below:

  • Design: Design principles are used to specify a biological system with an intended function, and models are used to help make a design according to these principles
  • Build: The desired DNA sequence encoding the biological system is constructed and implemented into a chassis, such as a target organism
  • Test: The function of the engineered biological system is assayed
  • Learn: The discrepancies between the desired and observed function are analysed to develop improved models and design heuristics

This process is repeated until a biological system with the desired function is identified. This incremental approach enables engineering despite our incomplete understanding of the complexities of biology.

This engineering cycle can also be applied to the development of models in the design stage.