Operational definition
Acquisition mechanism.
The movement of individual dissolved molecules or ions across the functional boundary of a cell or organism into a compartment where they can be metabolized, stored, regulated, or incorporated into biomass.
It includes:
- passive diffusion;
- channel-mediated diffusion;
- carrier-mediated facilitated diffusion;
- primary active transport;
- secondary active transport;
- group translocation.
The defining feature is that the acquired material crosses the boundary in molecular or ionic form rather than as a macroscopic particle.
6.1 Passive uptake
- simple diffusion
- channel-mediated diffusion
6.2 Facilitated uptake
- carrier-mediated transport
- selective permeases
6.3 Active uptake
- ATP-dependent transport
- ion-gradient-coupled transport
- group translocation
6.4 Gas uptake
- carbon dioxide
- oxygen
- hydrogen
- methane
- carbon monoxide
- gaseous nitrogen compounds