The key difference between coacervates and protobionts is that coacervates are the spherical macromolecular aggregates bounded by a membrane while protobionts, which are the precursors to early life, are microspheres composed of inorganic and organic molecules surrounded by a lipid bilayer membrane.
Coacervates and protobionts are cell-like structures, but they are not live structures. Coacervates are aggregates of charged polymers. They are membrane-bound, vesicle-like structures. Coacervates can absorb things from the surrounding and grow. They can also divide into new coacervates. Protobionts are aggregates of abiotically produced molecules surrounded by a lipid bilayer membrane. They are the precursors to early life. In fact, scientists think that protobionts were the evolutionary precursors to prokaryotic cells. They exhibit simple reproduction and metabolism. They are formed spontaneously from organic compounds.
CONTENTS
1. Overview and Key Difference
2. What are Coacervates
3. What are Protobionts
4. Similarities Between Coacervates and Protobionts
5. Side by Side Comparison – Coacervates vs Protobionts in Tabular Form
6. Summary
What are Coacervates?
Coacervates are the aggregates of colloidal droplets held together by electrostatic attractive forces. The term was used by I. A. Oparin. He believed that life developed from coacervates. Coacervates develop spontaneously under appropriate conditions. They are microscopic spherical aggregates of macromolecules such as proteins, lipids and nucleic acids. They are surrounded by a lipid membrane and also contain enzymes. Coacervates can grow by absorbing molecules from the environment. Moreover, they can divide by budding. Therefore, coacervates resemble living matter and were considered precursors of cells.
Figure 01: Coacervates
What are Protobionts?
Protobionts are microspheres composed of organic and inorganic molecules trapped inside a lipid bilayer. The internal environment of these microspheres is separated from the surrounding. They are formed spontaneously. They were the precursors to early life. They resemble very simple cells. The lipids of the membrane are called liposomes, and these liposomes can maintain a voltage across the membrane. Protobionts undergo simple reproduction via producing smaller liposome microspheres. When a self-replicating molecule is trapped inside or is formed inside of the protobiont, this structure has many characteristics of a prokaryote. Scientist believed that these protobionts are the first living prokaryotes. Protobionts show the origin of self-replicating molecules.
What are the Similarities Between Coacervates and Protobionts?
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- Coacervates and protobionts are spherical aggregations.
- Both are coated with a lipid membrane.
- Both resemble very simple cells.
- People believed that they are the precursors of cells.
- They are formed spontaneously.
- Both coacervates and protobionts are not live structures, but they exhibit basic properties such as metabolism, growth and reproduction.
What is the Difference Between Coacervates and Protobionts?
Coacervates are membrane-bound vesicle-like aggregates of lipid molecules while protobionts are aggregates of abiotically produced molecules surrounded by a lipid bilayer. So, this is the key difference between coacervates and protobionts. Oparin believed that life developed from coacervates. Protobionts are considered as the precursors to early life.
Moreover, coacervates are enclosed with a single membrane, while protobionts are enclosed with a lipid bilayer.
Below is a summary tabulation of the difference between coacervates and protobionts.
Summary – Coacervates vs Protobionts
Coacervates are microscopic spontaneously formed spherical aggregates of lipid molecules that are held together by electrostatic forces. Oparin believed that life developed from coacervates. Protobionts are the aggregations of organic and inorganic molecules surrounded by a lipid bilayer. They resemble living matter, and they are the precursor to early life or prokaryotic cells. Both coacervates and protobionts are cell-like structures, but not living cells. They show basic properties of life such as metabolism, growth and reproduction. Coacervates have a single membrane while protobionts have a lipid bilayer. Thus, this summarizes the difference between coacervates and protobionts.
Reference:
1. “The Coacervates.” Eniscuola, Available here.
2. “Protobionts.” Earthprokaryotes. Available here.
Image Courtesy:
1. “Coacervate droplets example” By Spruijtlab – Own work (CC BY-SA 4.0) via Commons Wikimedia