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In cellular biology, active is the movement of molecules or ions across a cell membrane from a region of lower concentration to a region of higher concentration —against the concentration gradient. Active transport requires cellular energy to achieve this movement. There are two types of active transport: primary active transport that uses ...
In contrast, paracellular transport is the transfer of substances across an epithelium by passing through an intercellular space between the cells. 1. It differs from transcellular transport, where the substances travel through the cell passing through both the apical membrane and basolateral membrane. 2. Renal physiology.
Membrane transport protein. A membrane transport protein is a membrane protein involved in the movement of ions, small molecules, and macromolecules, such as another protein, across a biological membrane. Transport proteins are integral transmembrane proteins; that is they exist permanently within and span the membrane across which they ...
As mentioned above, passive diffusion is a spontaneous phenomenon that increases the entropy of a system and decreases the free energy. [5] The transport process is influenced by the characteristics of the transport substance and the nature of the bilayer. The diffusion velocity of a pure phospholipid membrane will depend on: concentration ...
The two ways in which glucose uptake can take place are facilitated diffusion (a passive process) and secondary active transport (an active process which on the ion-gradient which is established through the hydrolysis of ATP, known as primary active transport). Active transport is the movement of ions or molecules going against the ...
Three-dimensional rendering of diffusion of purple dye in water. Diffusion is the net movement of anything (for example, atoms, ions, molecules, energy) generally from a region of higher concentration to a region of lower concentration. Diffusion is driven by a gradient in Gibbs free energy or chemical potential.
Exocytosis (/ ˌɛksoʊsaɪˈtoʊsɪs / [1][2]) is a form of active transport and bulk transport in which a cell transports molecules (e.g., neurotransmitters and proteins) out of the cell (exo- + cytosis). As an active transport mechanism, exocytosis requires the use of energy to transport material. Exocytosis and its counterpart, endocytosis ...
Glucose. Glucose transporters are a wide group of membrane proteins that facilitate the transport of glucose across the plasma membrane, a process known as facilitated diffusion. Because glucose is a vital source of energy for all life, these transporters are present in all phyla.