Cell Membrane Divides the Living Universe Into Two

The universe is composed of planets, stars, asteroids, and other matter too complex for a human mind to fully comprehend. From the point of view of humans, there is a living and a non-living component of this universe. For instance, on planet earth, there is a non-living universe composed of soil, water, air, and trace elements. There is also the living universe which is composed of plants, animals, microorganisms, and of course human beings. This living universe can be further simplified into a cell surrounded by other cells and what divides the cell from others is the cell membrane, hence it can be said that the cell membrane divides the living universe into two.

Overview

The basic component of life is a cell. A group of cells will create a living tissue and a group of tissues will make an organ and the organs will work together to form an organism capable of living on planet earth. It can be argued that organisms as simple as bacteria and something as complicated as a human body are part of a living universe. Observing these organisms with the naked eye there is not much to see except the basic forms that differentiate a toad from a fish for instance but on a microscopic level, one can easily discover that a cell membrane provides a barrier between the cell and the outside world.¹

This cell membrane does not only exist on the surface of the skin of these organisms but it is present in every living component of living things. The cell membrane does not only provide the first line of defense from the non-living world but it also separates one cell from another. Thus, the cell membrane makes one cell an independent unit capable of surviving on its own provided that it can have access to water and other vital nutrients and trace elements needed for survival. The best way to illustrate this mechanism is to describe it as a wall. But it is more complex than a mere wall trying to protect the vital components from invaders and other harmful agents. Thus it is much better to describe it as a membrane for it does not only provide cover it also allows the movement of micro-nutrients inside the cell as well as facilitate the excretion of waste outside of the same.

There are two types of cells – animal and plant cells. With regards to the cell membrane, the plant cell has a rigid cell wall while an animal cell membrane is a flexible lipid bilayer.² As mentioned earlier the cell membrane is not simply for covering or protection. It is not as static as a fortress but instead it is an active part of a living cell. The most accurate term that can be used to label it is a membrane but this is overly simplistic. A membrane can be misunderstood as a semi-permeable material and this is simply part of the functions of a cell membrane.

As a Barrier

The cell membrane acts as a boundary wall for the cell. It is like a buffer zone that separates the critical components of the cell from the harmful elements of the outside world. It is not hard to understand that vital components of the cell are very sensitive to foreign matter. One only has to have a basic understanding of the inner workings of the cell as well as the complicated tasks that it has to perform in order to have an understanding as to why the chemical balance of the cell must be kept at an optimum level.

The first major function of the cell membrane is to act as a barrier from the outside world. It must also be pointed out that the cell is not only separated from the harsh elements found outside the barrier but the cell is also separated from other cells.³ Therefore, the cell membrane also allows the cell to become an independent unit, working in tandem with other cells of the body but as a separate entity that is able to regulate its functions on a cellular level. If the human body can be likened to a universe then the cell can be compared to a spaceship floating in space and self-contained, with all the necessary apparatus needed to survive in an inhospitable environment.

This function is made possible by an ingenious design. The cell membrane is made up of protein and lipid and together these two components are assembled into two opposing layers called the lipid bilayer.⁴ Lipids are associated with fats and oils and this idea is useful in understanding the design of the cell membrane. But in the case of the cell membrane, it must be pointed out that there is a specific class of lipid that comprise this protective layer and this is class is called the phospholipids.⁵ Since the major component of the cell membrane is an organic matter belonging to fats and oils it is therefore easy to link it to a distinct characteristic of oils and fats which is its inability to mix with water. Since water is the universal solvent, the hydrophobic quality of lipids makes it impossible for water to enter and exit the cell.

The ability of the cell membrane to act as a barrier makes life possible on this planet. The compartmentalizing capacity of cell membranes allows cells to perform their basic functions without disturbance from the outside world. The key design is the use of a two-opposing layer made up of protein and fats. The protein provides structure while the lipid creates a barrier that makes it impossible for water and soluble materials to pass through. While the wall-like characteristics of a cell membrane are very important, it must be clarified that if it is only limited as a barrier then it will not take long before the cell will wither and die.

As Gateway

Aside from protecting the cell from the outside world, the cell membrane has a second major function and which is to regulate the movement of nutrients and water into the cell as well as to facilitate the excretion of waste material outside the boundaries of the cell membrane. Dirk Schulze-Makuch and Louis Irwin were able to summarize it in a few words when describing the qualities of the cell membrane when they said that it is a selectively permeable membrane, “…to preserve the high free energy state of the system from dissipation, encapsulate and confine a high concentration of interacting solutes and macromolecules, and carry out complex functions such as selective solute permeation, substrate interaction, and energy transduction.”⁶ Thus, it is not simply about separation but separating the necessary from the unnecessary in order to regulate specific functions.

Again, this highly compl within and without the cell is made possible ex interactionby the ingenious design of the phospholipid bilayer. It has also something to do with the negative and positive charge of ions, chemical reactions, and physical attributes of the system.⁷ But to simplify, one commentator remarked, “…the laws of energy, the properties of matter and the chemistry of the colloids can explain Life’s dynamics.”⁸ If there is a need to go into details then one will only have to focus on the characteristics of lipids. Aside from the basic design pointed out earlier that water and oil cannot mix which helps explain the capability of the cell membrane to prevent water from needlessly entering the cells there is another more complicated explanation for this phenomenon.

The cell membrane bilayer, “possess hydrophobic polar heads, and two hydrophobic fatty acid tails … the tails associate with each other to form a hydrophobic environment in the center of the bilayer, with the polar heads facing outward to interact with the charged aqueous environment of the cytoplasm, organelle lumen, or extracellular space.”⁹ Aside from the hydrophobic qualities of the lipid layer, there is another means of regulating the movement of materials from the cytoplasm and the external environment. This is made possible by the use of integral membrane proteins that acts as channels and form pore-like structures to facilitate the movement of said materials.¹⁰ Another way is the use of ion pumps that will help the cell regulate the concentration of substances such as sodium molecules for instance.¹¹ This ensures the survival of the cell.

Conclusion

It has been made clear that the cell membrane actively divides the living universe into two. It actively divides because it is not simply a barrier that helps protect the cell from the harmful effects of materials found in the external environment. The cell membrane is not only for defense but also a mechanism that regulates the flow of materials into and outside the cell. This is made possible by the ingenious design of the cell membrane which is made up of a material that not only provides structure but also allows the cell membrane to be semi-permeable. Dividing the living universe into two is a very important feature of the cell membrane. Without it, life would not be possible on this earth.

The cell is the basic component of life on this planet and it has to be protected for its vital functions to commence. The cell is not only sensitive to physical forces it is also sensitive to chemical reactions. This membrane will ensure optimum conditions exist for the cell so that it will not wither and die. On the other hand, it is not enough to protect the cell there is also the need to regulate its functions.

References

1. Krawetz, Stephen & David Womble. Introduction to Bioinformatics. New Jersey: Humana Press, 2003.
2. Poole, Robert. Advances in Microbial Physiology. CA: Academic Press, 1995.
3. Schulze-Makuch, Dirk & Louis Irwin. Life in the Universe. New York: Springer, 2008.
4. Scott, Alwyn. The Nonlinear Universe. New York: Springer, 2007.
5. ThinkQuest. Cell Anatomy: Cell Membrane. 2009.
6. Ulmshneider, Peter. Intelligent Life in the Universe. New York: Springer, 2006.

Footnotes

1. ThinkQuest. Cell Anatomy: Cell Membrane. 2009.
2. ThinkQuest. Cell Anatomy: Cell Membrane. 2009.
3. Poole, Robert. Advances in Microbial Physiology. (CA: Academic Press, 1995), p. 85.
4. Krawetz, Stephen & David Womble. Introduction to Bioinformatics. (New Jersey: Humana Press, 2003), p.26.
5. Ulmshneider, Peter. Intelligent Life in the Universe. (New York: Springer, 2006), p. 120.
6. Schulze-Makuch, Dirk & Louis Irwin. Life in the Universe. (New York: Springer, 2008), p. 33.
7. Poole, Robert. Advances in Microbial Physiology. (CA: Academic Press, 1995), p. 85.
8. Scott, Alwyn. The Nonlinear Universe. (New York: Springer, 2007), p. 214.
9. Krawetz, Stephen & David Womble. Introduction to Bioinformatics. (New Jersey: Humana Press, 2003), p. 26.
10. Ibid, p. 30.
11. Ibid.