Can we create life using synthetic biology?
Using SynBio to create synthetic cells
Introduction
The cell is the basic functional and structural unit of all living organisms. It is often referred to as the ‘building block of life.’ Robert Hooke discovered the cell in 1665. Although the natural living cells exist on this planet for at least 3.5 billion years, scientists have made efforts and succeeded in synthesizing a cell synthetically. This article is about one of the recent developments in synthetic biology named synthetic cells. Let us start from basics about cells and develop the concept of artificial cells. Let’s see if it is possible to make cells synthetically.
The cell is the organization of many biomolecules (proteins, lipids, sugars, nucleic acids, etc.), organelles, and cytoplasm( which consists of water as its primary component) within a membrane. These are a lot of terminologies. Let’s break the cell into its parts and read about them. It will help us to know the requirement to make cells artificially and create life.
Components of cell
As the fruit has layers around it to protect the material inside it, the cell has a layer called the cell membrane that protects it from its surroundings. The cell membrane consists of two layers of phospholipids and some proteins.
The brain of the cell is the nucleus. It comprises nucleic acids, proteins, and other biomolecules encapsulated in a membrane made of lipids (fats). The nucleus is the cell component that stores all the information related to the cell, its functioning, structure, etc.
Many parts of cells cannot function independently out of the cell but can be functional when they work collectively. Such elements of cells are called organelles. Scientifically, an organelle is a subcellular structure with one or more specific jobs to perform in the cell, much like an organ does in the body. Some of the important organelles are mitochondria, chloroplasts, endoplasmic reticulum, Golgi apparatus, etc.
The remaining part of the cell mainly consists of fluids called cytoplasm. Now, we know the basics of the components of the cell. Let us now understand the approach of scientists to make synthetic cells.
What are synthetic cells?
A synthetic cell is an engineered particle that mimics one or many functions of a biological cell. The term does not refer to a specific physical entity but rather to the idea that certain functions or structures of biological cells can be replaced or supplemented with a synthetic entity. Thomas Chang developed the first artificial cells at McGill University in the 1960s. These cells consisted of ultrathin membranes of nylon, collodion, or crosslinked protein whose semipermeable properties allowed diffusion(random movement of particles) of small molecules in and out of the cell. These cells were micron-sized and contained cell, enzymes, hemoglobin, magnetic materials, adsorbents, and proteins. These artificial cells can have applications in many fields, from medicine to the environment, and may be useful in constructing the theory of the origin of life.
The artificial cells can help us study the origin of life and develop a more accurate theory that supports the origin of life on earth. It is nearly difficult to remove some abundant or important molecules or proteins, which have been selected in the course of evolution, from the natural cell. If the molecules, which were not chosen during evolution by nature, are introduced in artificial cells to study the reason for selecting a few molecules for others for a specific function. For example, we all know that ATP(Adenosine triphosphate) is the cell's energy currency. But in the cell, many other biomolecules have high energy than ATP. Why has nature not chosen other biomolecules over ATP as the energy currency of the cell? Why was Adenosine Triphosphate(ATP) chosen over other triphosphates in the cell? All these questions may be answered by studying and doing research on synthetic cells.
How to make them?
There are mainly two methods to make synthetic cells:
- Top-Down Approach
- Bottom-up Approach
Top-Down Approach
In this method, the genome(the material inside the nucleus that stores all the information related to the cell)of the natural cell is removed from their nucleus(the brain of the cell). Then, the nucleus is filled with different combinations of genes. These cells are kept under observation and allowed to replicate. Some cells can survive, but some cannot. Scientists select the cells which can survive with a minimum amount of genetic material as artificial or synthetic cells for their research. So, natural cells can be modified to get artificial cells for study. This method is called the top-down approach. Top refers to more complex cells with a complex genome. Then, we reduce the complexity of the genome and bring down the complexity of the cell. So, this approach is a top-down approach.
Bottom-up approach
You might have guessed about this approach after reading about the top-down approach. If not, don't worry. Let us understand the bottom-up approach. In this method, the bottom refers to the lowest level of complexity of the organization, i.e., fundamental biomolecules that form cells. Then the complexity of the cell is brought up from least complex biomolecules to artificial cells. In this approach, the biomolecules are organized to make complex artificial cells with minimum organelles, membranes, genome, etc. required for cells to survive. These parts are assembled to make artificial cells.
Experimentally, the bottom-up approach is more complex and challenging than the top-down approach to make synthetic cells. The bottom-up approach involves making the complete machinery of the cell from scratch. In comparison, the top-down approach is just modifying the readymade machinery to get appropriate useful synthetic cells. Although challenging, the bottom-up method is extensively used to study the origin of life problem because the bottom-up approach allows us to remove and add desired molecules to the cell from scratch (initial stage). This helps in studying the evolution of cells and their components. Apart from these approaches, there are many other ways to make a cell using synthetic biology techniques.
Conclusion
Using synthetic biology, scientists successfully make a synthetic cell from scratch, i.e., non-biotic substances. We have created living things from non-living things. Do you think this method of making feasible? Try to read this literature to know more about artificial or synthetic cells.
