Do Animal Cells Have Plasma Membranes:5 Facts You Should Know


The plasma membrane is an outer envelope-like biological structure of a cell. Here we try to find out the answer of do animal cells have plasma membranes?

With the concern of the above question, do animal cells have plasma membranes or not? The answer is yes, animal cells have plasma membranes. Plasma membrane is the outer membrane of an animal cell which protects the interior of the cell from external environment or extracellular space.

The plasma membrane is basically an outermost  biological covering of every animal cell. The lipid bilayer of the membrane makes it hydrophobic and selectively-permeable in nature.

With giving protection to the outer substances it also allows some necessary materials such as enzymes, water, ions, etc to enter as per the need of the cell. The protein materials attached with the membrane helps to facilitate the process easily.

In some theories it is stated that the plasma membrane has a superior evolutionary significance. In the lifeless earth when some organic substances like phosphate, sugars, nucleic acids are just made in the natural environment, the lipid based plasma membrane with some protein substances covered those organic materials like an envelope and formed  the single most primitive cell (with the reference of theory of abiogenesis).

Sometimes it becomes very confusing that the plasma membrane is the only outer covering of all the cell types. It’s not true only in case of animal cells the plasma membrane is the outermost covering of the cell.

In case of plant cells (eukaryotic cells) and bacterial cells (prokaryotic cells) the plasma membrane is not the only outermost covering of the cell. Those cells have an extra envelope, cell wall outside to the plasma membrane. Hence in case of plant cells or bacterial cells not the plasma membrane but the cell wall is the outermost covering of the cell.

Do all animal cells have plasma membranes?

Yes, all animal cells have plasma membranes as the outermost covering of cells. From lower to higher groups of animals, from invertebrates to vertebrates, from fish to mammals and birds in all kinds of animals the cells have plasma membranes in it. 

With the concern of the question Do Animal Cells Have Plasma Membranes or not, we can also add that not only all animal cells, all of the living organisms including plants, bacteria, archaea, etc have plasma membranes in their cellular structure. But the structure of plasma membrane slightly differs according to the cell types. 

Do Animal Cells Have Plasma Membranes From Wikipedia.org

Plasma membrane structure in animal cell

There are several models proposed to represent the structure of plasma membranes. Among all of them two mostly granted models are-

Fluid mosaic model

Fluid mosaic model is one of the most acceptable models which can successfully describe a simple view of plasma membrane structure which is very relevant till now. In 1972  American biologist Garth L. Nicolson and Seymour Jonathan Singer described the fluid mosaic model in which they considered the plasma membrane as a two-dimensional liquid.

According to the theory the viscose phospholipids comprise hydrophilic heads which are pointed outside and hydrophobic tails inside the bilayer. The cholesterol, protein substances like Integral Proteins, Glycoproteins and carbohydrates are embedded within the lipid bilayer, giving the membrane a mosaic structure.

Lipid bilayer model

The lipid bilayer model is the most acceptable model to describe the structure of plasma membrane appropriately.

According to this the plasma membrane consists of two amphiphilic phospholipid layers. The hydrophobic tails of phospholipids of the two layers are facing each other, remains isolated from the surrounding cellular water. Hence the hydrophobic heads with phosphate attached are exposed to the intracellular and extracellular environment, forming the lipid bilayer.

Lipid bilayer from Wikimedia commons

The plasma membrane structure consists mainly of some lipid and protein substances such as phospholipids, glycolipids, sterols, Integral proteins, Lipid anchored proteins, Peripheral proteins, etc. It also contains some carbohydrates embedded within the membrane.

Plasma membrane function in animal cell

Gives protection from outer environment

The plasma membrane serves as a barrier between the intracellular and extracellular environment. It gives protection from outer mechanical and chemical damages to the interior of the cell. It helps to separate all the cellular activities from extracellular space. It is selectively permeable so that it only allows some necessary materials such as water, ions, etc to enter the cell as per the need of the cell.

Gives a shape the cell

The plasma membrane of a cell is also responsible for giving a shape to the cell. As the plasma membrane surrounds all the interior of the cell it also gives mechanical support, rigidity and a proper shape to the cell. 

Helps in cellular transport mechanisms

The plasma membrane regulates all the cellular transport mechanisms. Though it is selectively permeable, substances like ions or water molecules need the help of transmembrane proteins (channel proteins) to enter the cell. Its plasma membrane also facilitates diffusion through which carbon dioxide (CO2) or oxygen (O2) molecules can cross the plasma membrane for cellular respiration. 

Helps in cell signaling

The plasma membrane helps in cell signaling mechanisms also. The surrounding cells communicate with each other by signal transduction pathways. The plasma membrane releases some kind of marker proteins so that other cellular mechanisms can identify that particular substance and are induced to do their scheduled job.

Facilitates endocytosis and exocytosis

Plasma membrane facilitates endocytosis; it’s a mechanism through which the cell membrane engulfs macromolecules and produces a vesicle containing that ingested material. This process needs cellular energy to perform. There are two main types of endocytosis such as phagocytosis (through which cells engulf solid molecules)and pinocytosis (through which cells engulf liquid molecules).

Plasma membrane facilitates exocytosis; it’s a mechanism through which the cell releases undigested bulk transport molecules outside to the cell. Hence the plasma membrane opens a secretory portal through which the vesicles containing undigested molecules are inserted within the cell membrane. 

Maintains the cellular potential

The cell membrane also maintains the cellular potential of the cell according to the ion concentration of the cell. 

Animal cell plasma membrane diagram

Here we give a diagram of the plasma membrane to describe the structure of it.

Do Animal Cells Have Plasma Membranes

Plasma membrane diagram from Wikimedia commons

From the diagram of plasma membrane structure we can find the molecular components which make the whole structure of it. These components are-

Let’s have a closer look at the following components-

Phospholipids

Phospholipids are major components of plasma membrane contributing upto 50% of the structure. The hydrophobic tails of phospholipids of the two layers are facing each other, remains isolated from the surrounding cellular water. Hence the hydrophobic heads with phosphate attached are exposed to the intracellular and extracellular environment, forming the lipid bilayer.

Glycoproteins

Glycoproteins are present at the surface of the plasma membrane. It is hydrophilic in nature so that it places in the aqueous environment. It helps in cell to cell recognition mechanism. It also allows molecules to bind with other substances. 

Protein channels

Protein channels are integral proteins which open a hydrophilic pathway through which water molecules, ions can cross the hydrophobic plasma membrane without any interruption.

Globular proteins

Globular proteins are fibrous proteins present in plasma membranes which help in catalyzing various chemical reactions within the cell and also serve as chemical messengers of cell membrane.

Peripheral protein

Peripheral proteins are found at the surface or periphery of the plasma membrane. It isn’t embedded within the lipid bilayer, and remains attached at the surface area. It provides support to the plasma membrane structure and helps in extracellular communication of cells.

Carbohydrates

Some carbohydrate substances are also found within the cell membrane structure providing extra support to the cell membrane.

Cholesterol

Cholesterol molecules are also found within the cell membrane structure. It helps to reduce the fluidity of lipid bilayer and separates the hydrophobic tails of phospholipids to prevent crystallization of it. It reduces the permeability of cell membrane so that micro molecules cannot cross the hydrophobic zone of plasma membrane so easily. 

As a whole we can say that plasma membrane is very important in cellular structure. Through this article we try to give the answer of do animal cells have plasma membranes or not? We also describe the composition, structure and function of the plasma membrane briefly. Hope this article on plasma membrane will be helpful to you.

Piyali Das

Hello, I am Piyali Das, pursuing my Post Graduation in Zoology from Calcutta University. I am very passionate on Academic Article writing. My aim is to explain complex things in simple way through my writings for the readers. We can connect through LinkedIn https://www.linkedin.com/in/piyali-das-484019216 .

Recent Posts