Search results
Results from the WOW.Com Content Network
Exocytosis (/ ˌ ɛ k s oʊ s aɪ ˈ t oʊ s ɪ s / [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.
In cell biology, bulk flow is the process by which proteins with a sorting signal [definition needed] travel to and from different cellular compartments. In other words, bulk transport is a type of transport which involves the transport of large amount of substance like lipid droplets and solid food particles across plasma membrane by utilising energy.
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 ...
In cellular biology, active transport 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.
A distinguishing feature of diffusion is that it depends on particle random walk, and results in mixing or mass transport without requiring directed bulk motion. Bulk motion, or bulk flow, is the characteristic of advection. [1] The term convection is used to describe the combination of both transport phenomena.
The properties that are carried with the advected substance are conserved properties such as energy. An example of advection is the transport of pollutants or silt in a river by bulk water flow downstream. Another commonly advected quantity is energy or enthalpy. Here the fluid may be any material that contains thermal energy, such as water or air.
Passive diffusion across a cell membrane.. Passive transport is a type of membrane transport that does not require energy to move substances across cell membranes. [1] [2] Instead of using cellular energy, like active transport, [3] passive transport relies on the second law of thermodynamics to drive the movement of substances across cell membranes.
Secondary active transport is when one solute moves down the electrochemical gradient to produce enough energy to force the transport of another solute from low concentration to high concentration. [ citation needed ] An example of where this occurs is in the movement of glucose within the proximal convoluted tubule (PCT).