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Active transport. 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. There are two types of active transport: primary ...
In terms of membrane transport the gradient is of interest as it contributes to decreased system entropy in the co-transport of substances against their gradient. One of the most important pumps in animal cells is the sodium potassium pump, that operates through the following mechanism:
Intracellular transport is an overarching category of how cells obtain nutrients and signals. One very well understood form of intracellular transport is known as endocytosis. Endocytosis is defined as the uptake of material by the invagination of the plasma membrane. [4] More specifically, eukaryotic cells use endocytosis of the uptake of ...
A membrane transport protein (or simply transporter) is a membrane protein [1] 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 ...
Dark small circles in the network are mitochondria. The endoplasmic reticulum ( ER) is a part of a transportation system of the eukaryotic cell, and has many other important functions such as protein folding. It is a type of organelle made up of two subunits – rough endoplasmic reticulum ( RER ), and smooth endoplasmic reticulum ( SER ).
Axonal transport, also called axoplasmic transport or axoplasmic flow, is a cellular process responsible for movement of mitochondria, lipids, synaptic vesicles, proteins, and other organelles to and from a neuron 's cell body, through the cytoplasm of its axon called the axoplasm. [1] Since some axons are on the order of meters long, neurons ...
The endomembrane system is composed of the different membranes ( endomembranes) that are suspended in the cytoplasm within a eukaryotic cell. These membranes divide the cell into functional and structural compartments, or organelles. In eukaryotes the organelles of the endomembrane system include: the nuclear membrane, the endoplasmic reticulum ...
Mitochondrial shuttle. The mitochondrial shuttles are biochemical transport systems used to transport reducing agents across the inner mitochondrial membrane. NADH as well as NAD+ cannot cross the membrane, but it can reduce another molecule like FAD and [QH 2] that can cross the membrane, so that its electrons can reach the electron transport ...