Diffusiom, Osmosis and Active Transport
Diffusion, Osmosis and Active Transport
Substances will move through the membrane by diffusion. This is the random spreading out of particles until they are even. For example, when you put your instant coffee in boiling water, the coffee particles spread out and fill the entire mug, this is diffusion.
A second way that substances can move through the cell membrane is by osmosis. This is a special type of diffusion where water moves from a high to a low concentration through a 'partially permeable membrane', or a membrane specially shaped to only allow water molecules through.
To learn about Osmosis in more detail visit Osmosis
A final way that substances can be moved through a membrane is active transport. This is where important substances are moved by the membrane. This process requires energy.
Active Transport
Active transport is the mediated process of moving molecules and other substances across membranes.
Active transport differs from passive transport in that it utilizes chemical energy in the form of adenosine triphosphate, or ATP, to move molecules against the concentration gradient — from an area of lower concentration to an area of higher concentration.
There are two types of active transport:
Primary Active Transport
Primary active transport directly utilizes chemical energy to move molecules through a membrane.
The sodium-potassium pump, present in almost all animal cells, is an example of the use of primary active transport. It expends ATP energy to move sodium ions out of the cell and replace them with potassium ions.
This exchange leaves the interior of the cell more positively charged than the cell’s exterior. This means the sodium-potassium pump must overcome not only a concentration gradient but also an electrochemical gradient as well.
Secondary Active Transport
In secondary active transport, molecules are moved through a membrane as the direct result of the diffusion of another substance.
The sodium-calcium exchanger, or
Substances will move through the membrane by diffusion. This is the random spreading out of particles until they are even. For example, when you put your instant coffee in boiling water, the coffee particles spread out and fill the entire mug, this is diffusion.
A second way that substances can move through the cell membrane is by osmosis. This is a special type of diffusion where water moves from a high to a low concentration through a 'partially permeable membrane', or a membrane specially shaped to only allow water molecules through.
To learn about Osmosis in more detail visit Osmosis
A final way that substances can be moved through a membrane is active transport. This is where important substances are moved by the membrane. This process requires energy.
Active Transport
Active transport is the mediated process of moving molecules and other substances across membranes.
Active transport differs from passive transport in that it utilizes chemical energy in the form of adenosine triphosphate, or ATP, to move molecules against the concentration gradient — from an area of lower concentration to an area of higher concentration.
There are two types of active transport:
Primary Active Transport
Primary active transport directly utilizes chemical energy to move molecules through a membrane.
The sodium-potassium pump, present in almost all animal cells, is an example of the use of primary active transport. It expends ATP energy to move sodium ions out of the cell and replace them with potassium ions.
This exchange leaves the interior of the cell more positively charged than the cell’s exterior. This means the sodium-potassium pump must overcome not only a concentration gradient but also an electrochemical gradient as well.
Secondary Active Transport
In secondary active transport, molecules are moved through a membrane as the direct result of the diffusion of another substance.
The sodium-calcium exchanger, or