Diffusion

 

What is Diffusion?

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Diffusion is the process of movement of molecules under a concentration gradient or in trouble-free words the difference in the concentration of a substance between two spots is known as the concentration gradient. . It is an important process occurring in all living organisms. Diffusion provides movement of substances in and out of the cells. The molecules move from an area of high concentration to an area of low concentration until the concentration turn out to be equal throughout.

                   Diffusion happens in liquids and gases because their particles move randomly from place to place.

Examples of Diffusion

• When we put a tea bag in a cup of hot water so that it is dipped completely, it diffuses into the water and the color of water changes.
• When we spray a perfume or room freshener, it will get diffused into the air by which we can smell the aroma (pleasant smell).
• When we open the soda or cold drinks bottle than the carbon dioxide [CO₂] diffuses in the atmosphere.
• Small dust particles or pollutants or smoke diffuse into the air and cause air pollution.
• A few crystals of potassium permanganate in water will diffuse and turn the water purple.    
• As Sugar or Salt gets dissolved in water without having to stir it and changes its taste.                                                                                                                                                                                                                                             
  
  
                                                                                                                                                                                                                                                          Photo by Alina Vilchenko from Pexels                                                                               
• As we light the incense stick (agarbatti), its aromatic fragrant smoke gets diffused into the air and spreads throughout the room.

By adding boiling water into the dried noodles, the water diffuses causing rehydration which makes dried noodles plumper and wet through it.

 

Diffusion can be classified into two main types, namely, simple diffusion and facilitated diffusion

       I.            SIMPLE DIFFUSION

The substance moves through a semi permeable membrane or in a solution in absence of any help from transport proteins, this procedure is known as simple diffusion.

 

·      Simple diffusion does not require energy in order to take place

 

Ø Bacteria deliver small nutrients, water and oxygen into the cytoplasm through simple diffusion

Ø In a cell, water, oxygen and carbon dioxide molecules can pass directly through the cell membrane with no requirement of any energy along the concentration gradient. This is a form of simple diffusion.

    II.            FACILITATED DIFFUSION

Facilitated diffusion is a passive movement of molecules across the cell membrane from the region of higher concentration to the region of lower concentration by means of a carrier molecule.

·        Facilitateddiffusion requires ATP (Adenosine Triphosphate is an energy carrying molecule found in the cells of all living things).

·        Carrier proteins and channels are the two broad classes of facilitated transport proteins.

 

For instance:  

Ø  In the human body, glucose molecules, sodium and potassium ions use carrier proteins to pass through the cell membranes.

 

FACTORS AFFECTING DIFFUSION

There are a few factors that affect the process of diffusion, which individually and collectively changes the rate and scope of diffusion. These factors contain:

·        Temperature.

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i.            High temperature increases the energy of the molecules = increasing the rate of diffusion because of the movement of the molecules

ii.            Lower temperature decreases the energy  of the molecules= decreasing the rate of diffusion

 

·        An increase or fall in the concentration gradient

 

i.            The greater the difference in concentration, the quicker the rate of diffusion.

ii.            The minor the difference in concentration, the slower the rate of diffusion

 

 

·        Size of the Particle.

 

 

       i.            Larger particles (also the heavier particles than the smaller particles) will move more slowly and so will have a slower rate of diffusion.

     ii.             Smaller particles (also the less heavy particle than the larger particles) will diffuse faster because they can move faster.

 

·        Area of Interaction.

 

 

       i.            The greater surface area faster the diffusion.

     ii.            The smaller surface area slower the diffusion

 

WHAT MAKES DIFFUSION HAPPEN?

Diffusion is a natural and physical process, which happens on its own, without stirring or shaking the solutions. Liquid and gases undergo diffusion as the molecules are able to move randomly

      The particles collide with each other or with their container. This forces them to change direction. In the end, the particles are spread through the entire container.

 IMPORTANCE OF DIFFUSION

§  Diffusion is an important process which is involved in different processes of life of living beings.

§    Diffusion  is widely used in various fields such as biology, physics, chemistry, etc. 

§   Diffusion  is the net movement of particles, ions, molecules, solution, etc.

§   In all living organism, diffusion plays an important role in the movement of the molecules during the metabolic procedure in the cells

§   In living beings, substances move in and out of cells by the process of diffusion.

Following are the examples which show that diffusion plays an important role for living organisms.

1.     In the process of Respiration, it produces waste carbon dioxide [CO₂], causing the amount of carbon dioxide [CO₂] to increase in the cell. Finally, the carbon dioxide [CO₂] concentration in the cell is higher than that in the surrounding blood. The carbon dioxide [CO₂] then diffuses out through the cell membrane and into the blood.

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2. Diffusion  also occurs in plant cells. In all green plants, water present in the soil diffuses into plants through their root hair cells.

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The movement of ions across the neurons that generates electrical charge is due to  Diffusion