The type of transport that moves material against the concentration gradient with the use of energy is called active transport. That energy that it uses is usually in the form of adenosine triphosphate (ATP).
Generally, materials move with the concentration gradient (from an area of higher concentration to an area of lower concentration). This happens naturally without using any energy. To move materials against the concentration gradient (from an area of lower concentration to an area of higher concentration), cells need to use energy. This energy required to move molecules is obtained from ATP, which is generated through cellular metabolism.
There are two types of active transport– Primary and Secondary active transport.
Primary active transportIn primary active transport ions are moved across a membrane, creating a difference in charge across that membrane. This system uses ATP to move an ion into the cell while at the same time moving a second substance out of the cell. An example is the sodium-potassium pump. Found only in animal cells, the sodium-potassium pump expends energy to move potassium ions into the cell and sodium ions out of the cell. This action results in a difference in concentration and charge across the cell membrane.
Secondary active transportSecondary active transport moves materials across a biological membrane using the energy of the electrochemical gradient generated and stored by the primary active transport system. Using this energy allows other substances such as glucose and amino acids to move against their own gradients. There are two types of secondary active transport: symporter and antiporter. When two molecules are being transported in the same direction, the protein that transports them is called a symporter. When two molecules are being transported in opposite directions, the transporter is called an antiporter.
Examples of Active TransportCommon examples of active transport include secretion of proteins such as enzymes, antibodies and peptide hormones from different cells, movement of Ca2+ ions out of cardiac muscle cells, and transportation of amino acids across the intestinal lining in the human gut.