What is osmosis?

\( \newcommand\) • 1. Description of Diffusion and Osmosis A water solution that contains nutrients, wastes, gases, salts and other substances surrounds cells. This is the external environmentof a cell. The cell’s outer surface of the plasma membrane is in contact with this external environment, while the inner surface is in contact with the cytoplasm. Thus, the plasma membrane controls what enters and leaves the cell. The membrane permits the passage of some materials, but not all. The cell membrane is said to be selectively permeable. Small molecules, for example, may pass through the membrane. If no energy is required for substances to pass through the membrane, the process is called passive transport. We will discuss two examples of passive transport in this tutorial: diffusionand osmosis. Diffusion Although you may not know what diffusion is, you have experienced the process. Can you remember walking into the front door of your home and smelling a pleasant aroma coming from the kitchen? It was diffusion of molecules from the kitchen to the front door of the house that allowed you to detect the odors. Diffusion is defined as the net movement of molecules from an area of greater concentration to an area of lesser concentration. The molecules in a gas, a liquid or a solid are in constant motion due to their kinetic energy. Molecules are in constant movement and collide with each other. These collisions cause the molecules to move in random directions. Over time, however,...

What is Osmosis? Osmosis is a passive process and happens without any expenditure of energy. It involves the movement of molecules from a region of higher concentration to lower concentration until the concentrations become equal on either side of the membrane. Any solvent can undergo the process of osmosis including gases and supercritical liquids. Let us have a detailed look at the different types and effects of osmosis in detail. Also Refer:Â Osmotic Solutions There are three different types of solutions: • Isotonic Solution • Hypertonic Solution • Hypotonic Solution An isotonic solution is one that has the same concentration of solutes both inside and outside the cell. A hypertonic solution is one that has a higher solute concentration outside the cell than inside. A hypotonic solution is one that has a higher solute concentration inside the cell than outside. Types of Osmosis Osmosis is of two types: • Endosmosis– When a substance is placed in a hypotonic solution, the solvent molecules move inside the cell and the cell becomes turgid or undergoes deplasmolysis. This is known as endosmosis. • Exosmosis– When a substance is placed in a hypertonic solution, the solvent molecules move outside the cell and the cell becomes flaccid or undergoes plasmolysis. This is known as exosmosis. Also Read:Â Effect of Osmosis on Cells Osmosis affects the cells differently. An animal cell will lyse when placed in a hypotonic solution compared to a plant cell. The plant cell has thick w...

Osmosis Definition – So, what is osmosis? In simple words, osmosis is the movement of water through a special mixture of solutes like salt particles within the solvent. In osmosis, water moves from an area of higher concentration to lower concentration through a selectively permeable membrane A selectively permeable membrane is known as a cell membrane. These cell membranes have small openings that let the water molecules pass through them. But it won’t allow larger particles like salt molecules to move freely through it. Learning courses for your kids! Get free trial here Osmosis allows water to pass through cell membranes. The transfer of water from a dilute solution to a concentrated solution over a partly permeable membrane is defined as osmosis. To further explain the concept of osmosis for children, they must first understand what lower and higher concentrations of water are. We have to remember that water has a natural propensity to flow from higher to lower concentration areas. The increased concentration of water contains no or fewer solutes. Types of Osmosis There are two forms of osmosis: Endosmosis When a material is immersed in a hypotonic solution, the solvent molecules travel into the cell, causing the cell to become turgid or undergo de-plasmolysed. This is referred to as endosmosis. Exosmosis When a material is put in a hypertonic solution, the solvent molecules travel outside the cell, causing the cell to become flaccid or plasmolysed. This is known as ex...

Think about a semi-permeable membrane with a high solute concentration on the right side. This side has more solutes, which through a few mechanisms draws water across the semi-permeable membrane into the right side. This movement of water towards the high solute side is osmosis, and is technically due to pressure. (This pressure arises from the solutes binding to some of the water molecules so the solute side actually has less unbound water molecules than the solute free side which causes the pressure flow). Typically the term "osmotic pressure" refers to the pressure needed in the opposite direction to equalize the water movement into the higher solute side. Osmosis is travelling of water molecules through a semi-permeable membrane. When you have a cup of water and cover it with gauze. Then you turn it upside down and start spilling water. Water goes through holes in gauze. This is extremely simplified to the popint I wonder whether it is correct. In this case, permeability relies on mechanic characteristics, while in nature, usually, it is chemical permeability of cell membranes. 03:20 Sal stats talking about how the solute particles mechanically block the gaps of the semipermeable membrane and that's the reason why it's more probable for water molecules from the left to go to the right side of the membrane. But if some of these solute particles are blocking the gaps in the membrane at some times, then how come these bigger particles don't stop molecules of water on the...

Diffusion refers to the movement of molecules from an area of high concentration to an area of lower concentration. Osmosis is a type of diffusion specifically for water molecules moving across a semi-permeable membrane. A concentration gradient is the difference in concentration of a substance between two areas, which drives diffusion or osmosis. Created by Sal Khan. Unfortunatly, the previous answer was not correct. Facilitated diffusion refers to a type of passive diffusion (requires no energy) where channels are lined by proteins that facilitate the diffusion of larger molecules through a semi permeable membrane. In the video the instructor talks about the sugar molecules being too large to simply passively diffuse through the membrane. One way to allow those molecules (either prevented by size or hydrophilicity)to pass through this membrane is to place a protein channel that makes this passage possible. The actual process of diffusion is then an energetically free process. (We are not considering the energy costs associated with making the protein channel.) The previous poster was also incorrect when explaining pinocytosis. Pinocytosis is a type of cellular intake mechanism that can be described as a non-selective "gulp". The cell invaginates and takes in a relatively large quantity of the surrounding medium and digests any useable contents. This is done without the need for any receptor/ligand mechanism as is used in phagocytosis. I hope this helps! 15:00, why is it ...

How Reverse Osmosis Works In order to understand reverse osmosis, it helps to first understand how mass is transported via diffusion and regular osmosis. +, Ca 2+, Cl -) or larger molecules (e.g., glucose, urea, bacteria). Diffusion and osmosis are thermodynamically favorable and will continue until equilibrium is reached. Osmosis can be slowed, stopped, or even reversed if sufficient pressure is applied to the membrane from the 'concentrated' side of the membrane. Reverse osmosis occurs when the water is moved across the membrane against the concentration gradient, from lower concentration to higher concentration. To illustrate, imagine a semipermeable membrane with fresh water on one side and a concentrated aqueous solution on the other side. If normal osmosis takes place, the fresh water will cross the membrane to dilute the concentrated solution. In reverse osmosis, pressure is exerted on the side with the concentrated solution to force the water molecules through the membrane to the freshwater side. There are different pore sizes of membranes used for reverse osmosis. While a small pore size does a better job of filtration, it takes longer to move water. It's sort of like trying to pour water through a strainer (large holes or pores) compared to trying to pour it through a paper towel (smaller holes). However, reverse osmosis is different from simple membrane filtration because it involves diffusion and is affected by flow rate and pressure. Uses of Reverse Osmosis Re...