Search results
Results from the WOW.Com Content Network
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).
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 ...
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 ...
In the phenomenological approach, diffusion is the movement of a substance from a region of high concentration to a region of low concentration without bulk motion. According to Fick's laws, the diffusion flux is proportional to the negative gradient of concentrations. It goes from regions of higher concentration to regions of lower concentration.
Note that this simple theory predicts that this contribution to the diffusiophoretic motion is always up a salt concentration gradient, it always moves particles towards higher salt concentration. By contrast, the sign of the electric-field contribution to diffusiophoresis depends on the sign of β ζ {\displaystyle \beta \zeta } .
Punctuated equilibrium, theory in evolutionary biology; Sedimentation equilibrium, analytical ultracentrifugation method for measuring protein molecular masses in solution; Equilibrium Theory (Island biogeography), MacArthur-Wilson theory explaining biodiversity character of ecological islands
The Hill equation can be used to describe dose–response relationships, for example ion channel-open-probability vs. ligand concentration. [9] Dose is usually in milligrams, micrograms, or grams per kilogram of body-weight for oral exposures or milligrams per cubic meter of ambient air for inhalation exposures. Other dose units include moles ...
Two useful introductions to the fundamental theory underlying the unit of selection issue and debate, which also present examples of multi-level selection from the entire range of the biological hierarchy (typically with entities at level N-1 competing for increased representation, i.e., higher frequency, at the immediately higher level N, e.g., organisms in populations or cell lineages in ...