Cell To Cell Transport-Diffusion, Facilitated Diffusion, Active Transport

Introduction

Cell to cell transport involves the movement of materials across cell membranes. It includes both active and passive transport. While the latter does not require energy to proceed, active transport requires a lot of energy to process further. The process of passive transport happens through diffusion, facilitated diffusion, and osmosis. 

Unlike passive transport, active transport’s movement is towards higher concentration. Plant-water relations refer to the process through which plants control the hydration of the cells. That also includes the collection of water from the soil, the transportation within the plant, and the loss of water through evaporation. It is important to know about plant-water relations because water is important for both plants and animals.

Diffusion

Diffusion refers to the movement of molecules from an area of higher concentration to that of a lower concentration. Oxygen can get into the cells of the human body through the process of diffusion. Several factors are responsible for affecting the rate of diffusion. They are:

Temperature: Diffusion takes place faster only if the temperature is higher.

Molecular weight: Huge molecules have the tendency to diffuse slowly.

Concentration gradient: The diffusion will happen faster only if there is a steeper gradient.

Membrane surface area: Diffusion occurs quickly if there are more membranes available.

Membrane permeability: Some substances can diffuse more easily due to the presence of more membranes.

Polarity: The substances that are nonpolar diffuse more easily.

Facilitated Diffusion

Facilitated diffusion refers to the movement of molecules from an area of higher concentration to that of a lower concentration with the help of a carrier or protein channel. In other words, it is a form of facilitated transport that involves the passive movement of molecules. That also involves their concentration gradient that is guided by the presence of yet another molecule. 

The latter happens to be an integral membrane protein that forms a channel or a pore. Facilitated diffusion does not involve any high-energy molecules. We can take the examples of guanosine triphosphate (GTP) and adenosine triphosphate (ATP). The rest of the molecules move alongside their concentration gradients.

Passive Transport

Certain materials like oxygen and water can both enter and leave the cells without the latter having to expend energy. That is what we call passive transport. It usually occurs in a concentration gradient. That also means that the molecules will move from areas of higher concentration to areas having a lower concentration. In short, we call this process diffusion. When it involves a carrier or a protein channel, that becomes facilitated diffusion.

Active Transport

Active transport refers to the process in which multiple or large particulars, fluids, and cells move materials against the concentration gradient. Unlike passive transport, active transport requires energy. In other words, the cell must expend the adenosine triphosphate (ATP) molecules. Active transport is responsible for utilising cellular energy in the form of these ATP molecules. If you are looking for active transport study material, this information will be useful for you. 

Imbibition

Imbibition refers to a special type of diffusion in which the water is absorbed by solid particles. These particles are called colloids, and they cause an enormous increase in volume. The solution does not form in this process. The colloids are also hydrophilic in nature. The solid particles are called imbibants, and the liquid that is imbibed is called the imbibate. The phase of imbibition begins with the entry of water into the seed.

Osmosis

Osmosis refers to the diffusion or spontaneous passage of water or other solvents. That happens through a semipermeable membrane. Its main function is to block the passage of dissolved substances that are also called solutes. It can also be made to do work. Osmotic pressure refers to the external pressure that is applied to ensure zero net movements of a solvent across the membrane. It is a colligative property that depends on the molar concentration of the solute. Osmosis is considered an important process in biological systems. That is because all the biological membranes are semipermeable. This process causes what we term water potential.  

Plasmolysis

Plasmolysis refers to the process through which cells tend to lose water in a hypertonic solution. It is a typical response of the plant cells that are exposed to hyperosmotic stress. In this process, the protoplasm shrinks away from the cell wall of a bacterium or a plant. That happens due to the loss of water via exosmosis. It further results in the gap between the cell wall and the plasma membrane. 

Plasmolysis is of two types:

• Concave plasmolysis

• Convex plasmolysis

The contraction of the plasma membrane and protoplasm results in concave pockets during concave plasmolysis. This condition can be reversed through a hypertonic solution. On the other hand, convex plasmolysis is irreversible. In this case, the plasmolysed cell completely detaches itself from the cell wall.

Conclusion

The cell membrane is termed a multitasker as it provides the structure of the cell. It also protects the cytosolic contents of the environment. The membrane further allows the cells to act as specialised units. At large, it is responsible for maintaining the homeostasis of all the cells. The processes of active and passive transport are extremely important for the movement of the molecules across the membranes. The only difference is that passive transport or diffusion does not require energy to conduct the same. It is important to know about plant-water relations because water plays a vital role in the lives of all living organisms.