osmosis
Osmosis
If the concentration of molecules on both sides of a membrane is the same, nothing will happen to the molecules. Osmosis only occurs when there is an imbalance of the molecules across the cell membrane.
The cell membrane is permeable to water molecules even though they are polar, due to the fact that water molecules are small.
Active transport utilizes transport proteins within the cellular membrane. Endocytosis occurs through an envagination of the cellular membrane itself to form a vessicle. Active transport is for transporting small molecules in and out of the cell while endo and exocytosis are for transporting large molecules in and out of the cell.
it occurs in the cell membrane(through the cell membrane really)
Osmosis
The movement of water through a selectively permeable membrane is called diffusion. Water will always diffuse down a concentration gradient, from high solute concentration to low solute concentration.
Diffusion of gases easily occurs across a membrane. The gases will have to be converted into liquids so as to diffuse easily.
If the concentration of molecules on both sides of a membrane is the same, nothing will happen to the molecules. Osmosis only occurs when there is an imbalance of the molecules across the cell membrane.
The cell membrane is permeable to water molecules even though they are polar, due to the fact that water molecules are small.
Diffusion will most likely to occur where there is a high concentration of gas or water then the particles distibute evenly to the area of low concentration. for example if you could smell a turkey cooking in the oven from upstairs without anyone telling you.
Facilitated diffusion occurs when a substance is aided across a membrane by a special molecule called an ionophore. Ionophores allow some molecules to diffuse but not others, effectively speeding up the rate of diffusion of that molecule.
This is unique to each cell. Some particles are small enough to diffuse freely in most cells. Other particles require varying types of transport mechanisms to cross the cell membrane. If it is a substance the cell either needs to take in or get rid of, there are proteins and other mechanisms to accomplish this. There are even actions of the cell in order to export or import substances.
Osmosis is defined as the passive movement of water molecules from a region of low solute concentration to a region of high solute concentration through a partially permeable membrane; water molecules are thus exhibiting the movement.
The primary drivinf force for diffusion is a concentration gradient. There has to be an abundance of molecules at one region and a scarcity of molecules at another. This differential distribution of molecules where one region has more than the other is called a concentration gradient. In the presence of this gradient, diffusion occurs without the expenditure of energy. In cells, diffusion can occur through the cell membrane. Water molecules move into or out of the cell depending on where there are more water molecules. If there is more water outside the cell, water molecules move in and vice versa.
that happens when osmosis occurs
Simple Diffusion - Lipid soluble molecules diffuse across the plasma membrane of a cell, uses no ATP energy and only occurs down a concentration gradient.Facilitated Diffusion - Molecules use the aid of proteins scattered throughout the plasma membrane to help them diffuse into or out of a cell, uses no ATP energy and only occurs down a concentration gradient.Co-transport - A molecule such as glucose may have a lower concentration inside a cell than outside so it attaches to a carrier protein, as does a molecule that is higher in concentration inside than outside, a sodium ion for example. The glucose is pulled through the membrane because of its concentration gradient, as this happens the sodium ion is also pulled through. This uses no ATP energy but only occurs if a molecule can move down a concentration gradient (on an exam paper you would have to explain that the sodium moves against a concentration gradient to get full marks).Active transport - A molecule uses the aid of carrier proteins to diffuse against a concentration gradient, this does use ATP energy. The ATP is needed to make the carrier protein change shape. This only occurs against a concentration gradient.