Can you explain diffusion
The assistance comes, for instance, from the proteins embedded in a biological membrane. Basically, these two types of diffusion differ in the mechanism by which substances move — one that occurs without assistance and the other one that occurs with the help of transport proteins. Thus, in facilitated diffusion, the transport only occurs when the molecule is able to bind to the membrane protein transporter.
Both of them result in the net downhill movement of substances and do not require chemical energy to proceed. While diffusion is the movement of particles down their concentration gradient, active transport is the movement of particles against the concentration gradient. Since the movement is characteristically uphill this type of transport requires energy often in the form of adenosine triphosphate ATP.
Diffusion and osmosis are both types of passive transport. Thus, both of them occur in a downhill manner and without energy expenditure. The difference is the diffusing molecules or particles. In diffusion, the diffusing particles are the solutes of a solution. In osmosis, the diffusing particles are the solvent of the solution, i.
In osmosis, water molecules diffuse from an area of high water concentration to an area of low water concentration across a biological membrane. Water that is drawn towards a concentrated solution but does not involve a biological membrane is not osmosis.
The cell regulates the entry and exit of substances through its plasma membrane. Not all molecules can readily pass across this selective membrane due to its structure. The lipid bilayer feature of the plasma membrane prevents the passage of polar molecules.
Nevertheless, small nonpolar molecules and ions can pass through the lipid bilayer. The way through which polar molecules can pass through is via the proteins in the plasma membrane. The transmembrane integral proteins are membrane proteins involved in the transport of substances into and out of the cell.
In this table, the mechanism employed by certain types of molecules and ions in order to pass across the plasma membrane down their concentration gradient is shown. In plants and animals, diffusion is exemplified by the diffusion of gasses. In plants, the openings formed by the guard cells called stomata are where carbon dioxide enters and oxygen leaves the plant. The plant takes in carbon dioxide since it is one of the major reactants in photosynthesis. Oxygen, in turn, is a byproduct of photosynthesis and is then released as it diffuses into the environment through the stomata.
Similarly, in animals, respiratory gases are transported generally by simple diffusion. In humans, the diffusion of respiratory gases takes place at the capillary beds that separate blood from the tissue fluid.
In the lungs, carbon dioxide is released by diffusing from the blood into the alveoli and then breathed out. Oxygen, in turn, is breathed in, and then diffuses from the alveoli of the lungs into the blood. The oxygen then diffuses from the circulating blood to the various tissues of the body. Molecules move within the cell or from one cell to another through different strategies. Transport may be in the form of simple diffusion, facilitated diffusion, active transport, osmosis, endocytosis, exocytosis, epithelial transport, or glandular secretion.
This tutorial provides elaborate details on each of these mechanisms. Find out how. Read More. The movement of molecules specifically, water and solutes is vital to the understanding of plant processes.
This tutorial will be more or less a quick review of the various principles of water motion in reference to plants.
The human respiratory system is an efficient system of inspiring and expiring respiratory gases. This tutorial provides details of the different parts and functions of the respiratory system The gastrointestinal system breaks down particles of ingested food into molecular forms by enzymes through digestion and then transferred to the internal environment by absorption.
Find out more about these processes carried out by the gastrointestinal system through this tutorial The kidneys are responsible for the regulation of water and inorganic ions. Read this tutorial to learn about the different parts of the kidneys and its role in homeostasis The circulatory system is key to the transport of vital biomolecules and nutrients throughout the body. Learn about the different components and functions of the human circulatory system dealt with in detail in this tutorial.
The lymphatic system is also elucidated elaborately here Cell Biology. Skip to content Main Navigation Search. Dictionary Articles Tutorials Biology Forum. Definition of diffusion. Table of Contents. Diffusion is the passive movement of molecules or particles from an area of higher concentration to an area of lower concentration.
The concentration gradient incites them to diffuse. Since the movement is downhill, there is no chemical energy expenditure as opposed to active transport that uses chemical energy. The transport of molecules across a biological membrane without the aid of membrane proteins is called simple diffusion. Kidneys filter dangerous chemicals from your bloodstream through microscopic tubes called nephrons.
Nephrons separate blood from waste chemicals and toxins, then reabsorb the water and nutrients in the blood through diffusion. The rest goes through the bladder and out.
Your liver does all sorts of interesting things, but at the top of the list, it synthesizes proteins. You need those. Your body is made of them. In the process, it produces a potentially dangerous waste product called urea. Being largely made up of water, the human body is in a constant state of diffusing water from one place to another. In fact, the process is so constant and complex that MRIs sometimes focus solely on water diffusion in the body to track and diagnose illnesses.
Diffusion is one of the engines that run the natural world. As a universal physical phenomenon, a vast number of natural processes rely on diffusion. Not one of the nicer forms of diffusion, but here we are. Many agricultural, industrial and mechanical processes rely on the ability to produce other stuff as waste. That waste diffuses into the air and consequences ensue. An alloy is a combination of either two or more metals, or a metal and one or more elements.
Most are man-made, used for everything from steel skyscrapers to amalgam tooth fillings. Some, however, occur naturally. These come about through long-term exposure of a metal to a different substance and, you guessed it, diffusion. Atoms diffuse into gaps in the atomic structure or fill the spaces the structure naturally creates. Naturally occurring alloys like this include chromite , an iron-chromium alloy important to the production of stainless steel, and electrum , a gold-silver alloy used to make the first coins.
Crystals by nature have vacancies in their atomic structure. Atoms can diffuse into the tiny openings. When subject to compression, atoms will fill those vacancies, creating new vacancies and changing the atomic structure. Sounds fancy, right? It just means that the motion is happening inside one cell, rather than between several.
After new molecules enter a cell, they diffuse evenly through the cytosol. Specifically, leaves at night. At night, however, the stomata simply remain open and CO2 enters the plant through diffusion. Understanding what it is and how it works is a big step toward understanding the world around you.
Another type of diffusion you'll find in the world is cultural diffusion. In our article, Examples of Cultural Diffusion we illustrate how horizons are broadened and people become more culturally rich through the spread of different beliefs, activities, and even food. Ready for a little fun now? Try weaving these science idioms into your everyday speech, and watch as your humor diffuses into the conversation!
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