Agriculture Reference
In-Depth Information
In the following section, we'll explore some of the ways that electrochemical signals are
created and transmitted throughout the plant. Then, the wide array of possible effects that
can be activated through these mechanisms will be discussed. We'll begin by exploring
how electric fields influence cell membranes and the flow of ions.
The Cell Membrane
As we covered before, the 'cell membrane' is effectively a wall that keeps all operating
portions of the cell self-contained, separated from their external environment.
Electrochemical signals and nutrients are able to pass through this barrier by receptors and
protein transport structures embedded within the membrane.
Technically, the membrane isn't a solid wall; it is actually a wall that can selectively
allow some substances to pass through it while blocking others (known as a permeable
membrane). Gases such as oxygen and carbon dioxide can pass relatively freely through
thesemembranesusingsimplediffusion,whilewater,inorganicions(e.g.sodium,calcium,
potassium), and more complex metabolites (e.g. amino acids, antioxidants, and vitamins)
cannot.Insimplediffusion,thecellwallactslikeasimplebalanceintheformofapressure
valve, striving to keep chemical equilibrium by allowing the materials in excess on one
side of the boundary to only pass while blocking the flow of substances in the opposite
direction. Diffusion can be visualized by thinking about how a drop of ink placed into a
glass of water will eventually spread from a concentrated drop to form a uniformly colored
solution.
To transport larger, complex, or charged materials across the cell membrane, two other
types of methods are used:
transport * Ion pumps
Cell Membrane Transport Mechanisms
