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Thermodynamically the flow of substances from one compartment to another can occur in the direction of a concentration or electrochemical gradient or against it. If the exchange of substances occurs in the direction of the gradient, that is, in the direction of decreasing potential, there is no requirement for an input of energy from outside the system; if, however, the transport is against ...
[5] [6] [7] When a channel is opened, millions of ions can pass through the membrane per second, but only 100 to 1000 molecules typically pass through a carrier molecule in the same time. [8] Each carrier protein is designed to recognize only one substance or one group of very similar substances.
A transport protein (variously referred to as a transmembrane pump, transporter, escort protein, acid transport protein, cation transport protein, or anion transport protein) is a protein that serves the function of moving other materials within an organism. Transport proteins are vital to the growth and life of all living things.
Motile marine animals are commonly called free-swimming, [10] [11] [12] and motile non-parasitic organisms are called free-living. [13] Motility includes an organism's ability to move food through its digestive tract. There are two types of intestinal motility – peristalsis and segmentation. [14]
Because energy is required in this process, it is known as 'active' transport. Examples of active transport include the transportation of sodium out of the cell and potassium into the cell by the sodium-potassium pump. Active transport often takes place in the internal lining of the small intestine.
One class is involved in the protein (e.g. toxins, hydrolytic enzymes, S-layer proteins, lantibiotics, bacteriocins, and competence factors) export and the other in drug efflux. ABC transporters have gained extensive attention because they contribute to the resistance of cells to antibiotics and anticancer agents by pumping drugs out of the cells.
A respiratory pigment is a metalloprotein that serves a variety of important functions, its main being O 2 transport. [1] Other functions performed include O 2 storage, CO 2 transport, and transportation of substances other than respiratory gases.
To keep the flows separate, such an organism could have wedged itself in the rock of the hydrothermal vent, exposed to the hydrothermal flow on one side and the more alkaline water on the other. As long as the organism's membrane (or passive ion channels within it) is permeable to protons, the mechanism can function without ion pumps. Such a ...