Cellular Absorption of Herbicides Glossary

absorption

Process of moving a substance from one matrix into another.

absorption

Process of moving a substance from one matrix into another.

alkaline

Basic; having a pH higher than 7; having a lower concentration of H+ ions.

anion

An ion with a negative charge.

anionic

Having a negative charge.

apoplast

Regions or cells in the plant not bound by a membrane (i.e. the cell wall region between cells or xylem tissue; apoplastic means 'non-living' tissue. 

ATP

Adenosine 5'-triphosphate

auxin

Indole-3-acetic acid (IAA); the first plant hormone discovered; a plant hormone involved in many plant growth processes including embryo development, root and flower development, vascular differentiation, stem elongation, apical dominance and tropic response.

base

A chemical compound that accepts a proton.

cation

A positively-charged ion.

cationic

Having positive charge.

cell wall

A thin, mechanically strong structure surrounding all plant cells consisting of a complex mixture of polysaccharides and other polymers that are secreted by the cell and are assembled into an organized network linked together by a mixture of covalent and noncovalent bonds. Cell walls regulate cell volume and determine cell shape.

cholorplast

The organelle in plant cells that contains chlorophyll and is the site of photosynthesis.

cytoplasm

A compartment in a plant or animal cell surrounding the nucleus in which many cell organelles and molecules are suspended.

cytosol

The liquid substance of protoplasm, excluding all the organelles such as nuclei, plastids, ribosomes.

diffusion

Process whereby molecules move from areas of higher concentration to areas of lower concentration.

dissociate

(dissociation) – The splitting of a single chemical species into two ions, for example H2O to produce H+ and OH-.

dissociation

The release of a proton from a molecule due to a change in pH.

efflux

Movement from the cytoplasm to the cell wall region; out of the cell.

electrochemical potential

Gradients of concentration and electric potential across cell membranes.

endogenous

Found naturally in an organism.

functional group

an atom or group of atoms within a molecule that shows a characteristic set of physical and chemical properties.  For example, hydroxyl groups (-OH) are present in alcohols, carbonyl groups (-C=O) are present in ketones and aldehydes, and carboxyl groups (-COOH) are present in carboxylic acids.

glyphosate

A herbicide which inhibits the production of amino acids.

herbicide

A pesticide used to kill plants.

herbicide

A pesticide used to kill plants.

hydrophilic

Water loving; having chemical properties relating to water (water-like); polar compounds that are highly soluble in water or polar solvents

hydrophobic

Water "fearing"; compounds that are relatively insoluble in water and other polar solvents and soluble in lipids and other nonpolar solvents.

influx

Movement from the cell wall region into the cytoplasm; into of the cell.

ions

Molecules with a positive or negative charge.

Kow

Octanol/water partition coefficient; relative measurement of how water soluble a chemical is; a compound with a low Kow would be more water-soluble than a compound with a high Kow.

lipid bilayer

Made up of compounds which have both hydrophobic and hydrophilic moieties, this is the structure of membranes such as the cellular membrane.

lipid bilayer

Made up of compounds which have both hydrophobic and hydrophilic moieties, this is the structure of membranes such as the cellular membrane.

lipids

A structurally diverse group of hydrophobic compounds that are soluble in organic solvents and highly insoluble in water.

lipophilic

Having chemical properties relating to lipids (lipid-like), nonpolar compounds that are highly soluble in organic solvents, but not water; hydrophobic.

log Kow

Octanol/water partition coefficient, relative measurement of how water soluble a chemical is. A compound with a low log Kow would be more water-soluble than a compound with a high log Kow.

metabolism

Alteration in the herbicide chemical structure usually detoxifies the herbicide. Metabolism is the most important mechanism of herbicide selectivity among weed and crop plants.

pH

Negative log of the hydrogen ion concentration (pH = -log [H+]), the higher the pH of an environment the less H+ ion concentration, the more basic the environment becomes.

phosphate

Used, instead of phosphorus, in fertilizer technology to refer to available phosphoric acid (P2O5).

photosynthesis

The conversion of light energy into chemical energy by plants using low-energy inorganic compounds (carbon dioxide) to produce high-energy organic compounds (sugars)

phytotoxicity

An agent which is toxic to plants.

plasma membrane

The semi-permeable membrane that surrounds the protoplasm of a cell.

polar

More hydrophilic or water loving.

polar solvent

Hydrophilic solvent; molecules containing functional groups with dipole moments.

proteins

Large molecules composed of one or more chains of amino acids in a specific order. Proteins are necessary for the structure, function, and regulation of the organism's cells, tissues, and organs. Each protein has a unique function determined by its shape.

proton

A positively-charged atomic particle; a hydrogen ion H+.

protonated

Having a proton attached, usually it is a H+ when considering herbicides.

site of action

The exact binding spot of a herbicide.

site of action

The exact binding spot of a herbicide.

solubility

The ability of a solute to dissolve in a solvent.

soluble

A state change when a solid material is put into a solvent. The molecules leave the solid phase and go into the liquid phase of the solvent

solution

A liquid matrix where a solute has been dissolved in a solvent.

tonoplast

The vacuolar membrane in plant cells.

vacuole

A membrane-bound (tonoplast) space larger than a vesicle which stores material, either dissolved in water or as a crystalline or flocculent mass. Vacuoles are key organelles for storage of compounds and osmoregulation in plants.

weak acid

An organic acid which is incompletely inonized in aqueous solution.