Active and passive transport are two processes that help supply nutrients, water, oxygen, and other essential molecules to the body’s cells. Waste products are also eliminated with the help of passive and active transport. They have similar purposes but different movements.
Passive transport
The selectively permeable or semipermeable phospholipid membrane, which is the most important feature of the cell, has control over the molecules of the cell. The organization and characteristics of a membrane are responsible for the permeability of the membrane.
A state of homeostasis within the cell (tissues, organs, and organ systems) is maintained with the help of the cell membrane, which makes the organism stay alive and healthy. The figure below shows that the ions leave or enter the cell as controlled by the membrane.
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Transport across membranes
Hydrophobic molecules like carbon dioxide and oxygen can easily pass through the phospholipid membrane. In contrast, the membrane does not allow the hydrophilic molecules to pass through because of their water-loving nature.
Transport proteins help the large molecules like sugar and proteins to pass through the membrane, and hence there is no contact between polar and nonpolar molecules, and the large molecules are moved through large pores.
Passive transport is one of the ways to pass molecules through phospholipids membrane with no energy input. There are three main types of passive transport-
Diffusion: It helps the molecules to move from the region of high concentration of molecules to the region of lower concentration. Concentration gradient is the term for the difference between the concentrations of molecules in the two areas.
Facilitated diffusion: It involves the diffusion of solutes through transport proteins. Even though there is an involvement of transport proteins, it is still passive transport because the movement of the solutes is down the concentration gradient.
Osmosis: Diffusion of water molecules through a selectively permeable membrane from higher water concentration to lower water concentration is called Osmosis.
Active transport
Contrary to passive transport, where there is no energy requirement for the movement of molecules and ions are carried down the concentration gradient, active transport pumps molecules against the concentration gradient. Here, energy is required. Energy is used in the form of ATP to move the molecules against the concentration gradient.
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Transport proteins, also known as protein pumps, transport the small molecules or small ions across a cell membrane, as shown in the figure. The larger molecules (for example-starch) can also be transported actively through the membrane with the help of vesicle transport processes called endocytosis and exocytosis.
What are endocytosis and exocytosis?
Endocytosis: The process of transport of particles from outside the cell to the inside of the cell is called endocytosis. The membrane of the cell folds over the particle, which makes it completely enclosed. The vesicle then pinches off and moves the particle into the cytosol. Endocytosis has two types-
Phagocytosis: A phagocytic vesicle is formed by the plasma membrane, which engulfs the solid material when dissolved in the cell.
Pinocytosis: It occurs when the plasma membrane folds inward to form a channel allowing the dissolved substances to enter the cell. The liquid is encircled with a pinocytic vesicle when the channel is enclosed.
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Exocytosis: When the vesicle fuses with the plasma membrane and releases its content outside the cell, it is called exocytosis. When protein-like substances are produced by the cell for export or when the cell gets rid of a waste product, exocytosis occurs. Newly-made membrane lipids and proteins are moved on the top of the plasma membrane by exocytosis.
| -Cellular energy is required. | -Does not require cellular energy. |
| -Movement takes place from a region of lower concentration to a region of higher concentration of molecules. | -Movement takes place from a region of higher concentration to a region of lower concentration of molecules. |
| -It is needed for the transportation of all molecules such as proteins, large cells, ions, etc. | -It is needed for the transportation of all soluble molecules, including oxygen, water, carbon dioxide, lipids, sex hormones, etc. |
| -It is a rapid process. | -It is a comparatively slow process. |
| -Carrier proteins are required in active transport | -Carrier proteins are not required in passive transport |
| -Metabolic inhibitors can influence and might make the transportation stop | -Transportation is not affected by metabolic inhibitors |
| -Transpires in a single direction | -Transpires in multiple directions. |
Conclusion
The two biological processes-Active and Passive transport have different types of movement.
Energy is required in only one of the two processes i.e active transport.
Both the processes transport molecules into the cell by different methods.
FAQs
1. What are the examples of active and passive transport?
Phagocytosis, pinocytosis, and sodium-potassium pump are examples of active transport while diffusion, facilitated diffusion and osmosis are examples of passive transport.
2. What is the difference between active and passive transport?
Active transport involves the movement of molecules from lower concentration to higher concentration with the use of energy. Passive transport involves the movement of molecules from higher concentration to lower concentration and no amount of energy is required.
3. What are the four types of active transport?
Active transport involves endocytosis and exocytosis. Endocytosis is further divided into phagocytosis and pinocytosis.
4. What are the three types of passive transport?
Diffusion, facilitated diffusion and osmosis are the three types of passive transport which do not require energy to move the particles.
5. Is diffusion active or passive?
Diffusion is a type of passive transport that does not require energy. Diffusion helps the molecules to move from a region of high concentration to a region of low concentration.
6. Is osmosis a type of active transport?
No, osmosis is a type of passive transport. It carries out-diffusion of water molecules through a selectively permeable membrane.
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Home » Biology » Active vs passive transport- Definition, 18 Differences, Examples
Active and passive transport are the two main biological process which plays an important role in supplying nutrients, water, oxygen, and other essential molecules to cells and also by removing waste products.
- Both active and passive transport works for the same cause, but with different movement.
- Active transport requires chemical energy because it is the movement of biochemicals from areas of lower concentration to areas of higher concentration.
- On the other hand, passive transport moves biochemicals from areas of high concentration to areas of low concentration; so it does not require energy.
Image Source: BIONINJA
Key differences (active transport vs passive transport)
| S.N. | Character | Active Transport | Passive Transport |
| 1. | Definition | The movement of molecules across the cell membrane, pumping the molecules against the concentration gradient using ATP (energy) is called Active transport. | The movement of molecules within and across the cell membrane and thus transporting it through the concentration gradient, without using ATP (energy) is called Passive transport. |
| 2. | Energy requirement | Energy is required which is in the form of ATP. | No energy is required. |
| 3. | Concentration Gradient | The movement of molecules is from low concentration to high concentration which means they move against the concentration gradient. | The movement of molecules is from high concentration to low concentration, which means they move along the concentration gradient. |
| 4. | Direction of movement | With the use of ATP, it pumps the molecules upwards. | In this, the molecules are moved downwards. |
| 5. | Carrier Protein or Pumps | Active transport requires carrier proteins. | In passive transport carrier proteins are not involved. However, in facilitated diffusion certain channels are present which utilize no energy. |
| 6. | Involvement of matrix or permeases | Matrix or permeases of the membrane are not involved. | It takes place through matrix/channels/permeases. |
| 7. | Efficiency of the Process | It is a rapid process. | It is comparatively a slow process. |
| 8. | Principle of Working | Active transport allows molecules to pass the cell membrane, disrupting the equilibrium established by the diffusion. | A dynamic equilibrium of water, nutrients, gasses, and wastes is maintained by passive transport
Between cytosol and extracellular environment. |
| 9. | Directionality | Occurs in one direction. | Bidirectional process. |
| 10. | Process type | Active transport is a vital process. | Passive Transport is a physical process. |
| 11. | Selectivity | It is highly selective. | It is partly non-selective |
| 12. | Effect of Temperature | Affected by temperature. | Not affected by temperature. |
| 13. | Effect of Oxygen Level | This process reduces or stops as the level of oxygen content is reduced. | This process is not affected by the oxygen content. |
| 14. | Effect of metabolic inhibitors | Metabolic inhibitors stop the active transport. | Metabolic inhibitors do not influence passive transport. |
| 15. | Molecules Transported | Macromolecules like proteins, carbohydrate (sugars), lipids, large cell are few of the materials which are transported by this way. | Oxygen, monosaccharides, water, carbon dioxide, lipids are the few soluble materials which are being transported through this way. |
| 16. | Types | Active transport is classified into two categories, like primary active transport and secondary active transport.
Endocytosis, cell membrane/sodium-potassium pump & exocytosis |
Passive transport is classified into four categories like osmosis, diffusion, facilitated diffusion, and filtration. |
| 17. | Functions | Though the function of both types of transport is to carry ions and molecules, separately active transport is used to carry through the cell membrane. | It is used to maintain the equilibrium, within and outside the cell of nutrients, water and gases, etc. |
| 18. | Examples | Examples of active transport include a sodium pump, glucose selection in the intestines, and the uptake of mineral ions by plant roots. | Passive transport occurs in the kidneys and the liver, and in the alveoli of the lungs when they exchange oxygen and carbon dioxide. |