Key Functions and Structure: Cell Membrane vs Plasma Membrane
The cell in the human body is a very intriguing thing to study to say the least. It is a brilliant example of how smart the human body is and what exactly it does to keep itself alive. The human cell was initially known to have lesser components than what we know now. We know that the human body is a wonderful machine that does most of its job involuntarily without our involvement in it. The cell is also the same. The cell carries out most of its function without our conscious control over it and leads to the survival of our bodies. There are certain components of a cell. In this article we will be taking a look at two of the most important parts of the cell structure. The Cell Membrane and the plasma membrane.
Both Cell membrane and plasma membrane are integral parts of cell structure. These two components are the protective layers that protect the cell from external shocks.
The cell organelles, along with all the ions and molecules, are surrounded by these two layers. Often these two terms are used synonymously, but the difference between cell membrane and plasma membrane is substantial.
What is Plasma Membrane?
Plasma membrane is a kind of phospholipid membrane, present in all cells. It protects the protoplasm of a cell from outer hazards and checks the movements of molecules in and out of a cell.
What is Cell Membrane?
Cell membrane is a thin multifaceted layer that acts as a barrier between the inner parts of a cell and the other part. It protects the cytoplasm of a cell and also provides shape to a cell. This particular membrane is a part of all cells, animals and plants.
However, in plant cells, algae and fungi, a cell wall is present and it envelopes the membrane. It is a kind of plasma membrane.
Once you know the basic concepts of these membranes, it will be easier for you to differentiate between plasma membrane and cell wall. Let’s begin!
Plasma Membrane vs Cell Wall
There are a few differences between plasma membrane and cell wall. Some of them are discussed below.
Apart from these, the most fundamental difference between plasma membrane and cell wall is that the former one is present in the inner lining of all cells while the latter one protects the membrane (specific cells).
MCQ: which organelle participates in cell wall synthesis?
Chloroplast
Mitochondria
Lysosome
Golgi apparatus
Ans. 4
Conclusion
We hope that students understood details about the functions, texture, permeability, composition, and structure of the cell membrane and the plasma membrane and also how different they are from each other. Keep this article handy for future use!
FAQs on Difference Between Cell Membrane and Plasma Membrane
1. Are the cell membrane and plasma membrane the same thing?
Yes, for all practical purposes, the cell membrane and plasma membrane are the same structure. Both terms refer to the biological barrier that encloses a cell's cytoplasm. The term 'plasma membrane' is often used in higher studies to specifically denote the outer boundary of the cell, distinguishing it from the internal membranes that surround organelles like the nucleus.
2. What are the main functions of the plasma membrane?
The plasma membrane is vital for a cell's survival and performs several key functions as per the CBSE syllabus:
- Selective Permeability: It acts as a gatekeeper, controlling which substances enter and leave the cell.
- Protection: It forms a protective barrier that separates the cell's internal contents from the external environment.
- Transport: It facilitates the movement of essential molecules and ions through processes like diffusion, osmosis, and active transport.
- Cell Signalling: It contains receptor proteins that allow the cell to respond to external signals.
3. What is the primary difference between a cell membrane and a cell wall?
The key difference is that the cell membrane is a thin, living, semi-permeable layer found in all cells (plant and animal), composed of lipids and proteins. In contrast, the cell wall is a thick, non-living, fully permeable layer found only in plants, fungi, and bacteria. It is located outside the cell membrane and is made of cellulose (in plants), providing rigid structural support.
4. What is the plasma membrane made of, according to the fluid mosaic model?
According to the widely accepted fluid mosaic model, the plasma membrane is primarily composed of a flexible phospholipid bilayer. This 'fluid' sea of lipids has various proteins embedded in it, which look like a 'mosaic'. These proteins serve as channels and pumps for transport. In animal cells, cholesterol is also present, which helps maintain the membrane's fluidity.
5. Why are the terms 'cell membrane' and 'plasma membrane' used interchangeably?
The terms are used interchangeably because they describe the same essential structure: the cell's outer boundary. The term 'plasma membrane' gained popularity to create a clear distinction between the cell's external boundary and the various other membranes found inside the cell (endomembranes), such as the nuclear envelope or the endoplasmic reticulum. However, in most contexts, 'cell membrane' correctly refers to this outer plasma membrane.
6. How does the semi-permeable nature of the plasma membrane support life?
The semi-permeable nature of the plasma membrane is fundamental for maintaining homeostasis—a stable internal environment necessary for life. It allows essential substances like water and oxygen to enter while preventing harmful agents from invading. It also ensures that waste products can exit the cell. This precise regulation of molecular traffic is critical for all cellular activities, from generating energy to responding to the environment.
7. What is the key difference between the plasma membrane and the nuclear membrane?
The primary difference lies in their location and structure. The plasma membrane is the single-layered outer boundary of the entire cell. The nuclear membrane, found only in eukaryotic cells, is a double-layered membrane that surrounds the nucleus. A key feature of the nuclear membrane is the presence of 'nuclear pores', which are specialized channels that regulate the transport of molecules specifically between the nucleus and the cytoplasm.
