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The grey represents the concentration of a molecule. A biomolecular gradient is established by a difference in the concentration of molecules in a biological system such as individual cells, groups of cells, or an entire organism. A biomolecular gradient can exist intracellularly (within a cell) or extracellularly (between groups of cells).
In developmental biology, 'morphogen' is rigorously used to mean a signalling molecule that acts directly on cells (not through serial induction) to produce specific cellular responses that depend on morphogen concentration. This definition concerns the mechanism, not any specific chemical formula, so simple compounds such as retinoic acid (the ...
Fick's first law relates the diffusive flux to the gradient of the concentration. It postulates that the flux goes from regions of high concentration to regions of low concentration, with a magnitude that is proportional to the concentration gradient (spatial derivative), or in simplistic terms the concept that a solute will move from a region of high concentration to a region of low ...
Ions travel across cell membranes through channels, pumps or transporters. In channels, they move down an electrochemical gradient to produce electrical signals. Pumps maintain electrochemical gradients. The main type of pump is the Na/K pump. It moves 3 sodium ions out of a cell and 2 potassium ions into a cell.
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.
This glossary of biology terms is a list of definitions of fundamental terms and concepts used in biology, the study of life and of living organisms.It is intended as introductory material for novices; for more specific and technical definitions from sub-disciplines and related fields, see Glossary of cell biology, Glossary of genetics, Glossary of evolutionary biology, Glossary of ecology ...
Concentration gradients can develop relatively quickly and persist for a long time in the system; Chemotactic and chemokinetic activities are distinguished; Migration of cells is free toward and away on the axis of the concentration gradient; Detected responses are the results of active migration of cells
The French flag model is a conceptual definition of a morphogen, described by Lewis Wolpert in the 1960s. [2] [3] A morphogen is defined as a signaling molecule that acts directly on cells (not through serial induction) to produce specific cellular responses dependent on morphogen concentration. During early development, morphogen gradients ...