Herbicide Discovery and Screening Glossary

active site

The location on an enzyme (protein) to which substrate molecules bind and are converted to their products. The shape of this site must be maintained for the enzyme to remain functional.


Annotations are the descriptive information, references to published articles, and other explanatory material that are added to a gene sequence.

antisense RNA

A synthetic mRNA molecule with the opposite, or complementary, sequence of the actual in vivo molecule. The antisense version will bind to its counterpart and thus reduce or abolish gene expression.


An abbreviation for complementary DNA; a DNA molecule made from an mRNA template that represents the entire coding region of the gene, but not the intron sequences.


A subclass of of Angiosperms.

They tend to have:
-broad leaves
-two cotyledons
-netlike veins in the leaves
-flower parts are usually in fours or fives
-a ring of primary vascular bundles in the stem
-taproot system

ex. most trees and shrubs, broadleafs


(deoxyribonucleic acid) The molecule that encodes genetic information. DNA is a double-stranded molecule held together by weak bonds between base pairs of nucleotides. It is the fundamental substance of which genes are composed.


Found naturally in an organism.


Special protein molecules which function in catalyzing chemical reactions.

eukaryotic expression system

A culture of yeast or baculovirus cells that, when transformed with a plasmid containing a cDNA, can express large quantities of the encoded protein.

Expressed Sequence Tags

Short fragments of cDNAs that are used as markers or tags for expressed genes in genomic and mapping research.


The fundamental unit of heredity that carries genetic information from one generation to the next. A gene is an ordered sequence of nucleotides located on a particular position on a particular chromosome that encodes a specific functional protein.

gene expression

The production of a protein encoded by a gene. Gene expression is controlled by the promoter region of the gene.

gene silencing

The inactivation of a gene by an organism to prevent the gene from expressing.


All the genetic material in the haploid set of chromosomes for a particular organism.


A pesticide used to kill plants.

in vitro

In an experimental situation outside the organism (literally, "in glass").

in vitro assay

Literally, "in glass" assay containing cellular components like enzymes and their substrates and co-factors, but not whole cells. 


The dose of chemical that can kill 50% of the test subjects.

mechanism of action

The specific process inhibited by a herbicide.


A general term referring to the change of a herbicide from an active to an inactive state.

microtiter plates

Plastic plates containing many (96 to 864) small wells in which individual reactions or assays can be conducted; their format is designed for robotic manipulators and detectors.

mode of action

How a herbicide affects a plant including uptake, translocation and general effect on a plant.


(messenger ribonucleic acid) The message made during transcription by reading the DNA sequence to build a particular protein. A single-stranded nucleic acid similar to DNA but having a ribose sugar rather than deoxyribose sugar and a uracil rather than thymine as one of the bases.

oligonucleotide libraries

Collections of many different, short (usually <30 nucleotides) DNA fragments.


Any substance or mixture of substances used for controlling, preventing, destroying, repelling, or mitigating any pest. A pesticide also includes any substance or mixture of substances intended for use as a plant regulator, defoliant, or dessicant.


The observable physical characteristics of an organism that are determined by a combination of the genetic composition (genotype) and the environment of the individual.


An array of pigment-protein complexes and electron transfer components that function together to harvest light energy, transfer the energy to photochemical reaction centers, and move the excited electrons in a controlled fashion to produce usable biochemical energy. Each photosystem contains hundreds of chlorophyll and carotenoid molecules functioning as antennae, while only a few chlorophyll molecules are employed in the reaction centers.

principal component analysis/cluster mapping

A statistical method of reducing a dataset of two or more correlated variables, usually resulting in a regression relationship, in order to detect inherent structure. 


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


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.


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


Ribonucleic Acid.  A single-stranded nucleic acid similar to DNA but having a uracil rather than thymine as one of the nucleotides. The RNA strand carries the coded information from the nucleus to the cytoplasm where protein production occurs.


A herbicide that is toxic to certain plants but harmless to others.


Determination of the order of nucleotides in a DNA or RNA molecule or the order of amino acids in a protein.


The ability of a solute to dissolve in a solvent; the ability of a herbicide to dissolve in water.


A fundamental category of taxonomic classification, ranking below a genus or subgenus and consisting of related organisms capable of interbreeding.

substituent groups

Atoms, radicals, or groups in a chemical compound.

transcription factors

Proteins that interact with DNA in regulatory regions upstream (usually) of genes to induce or repress gene expression.


The process of introducing a foreign cDNA or gene construct into a plant, usually through biolistic bombardment or using Agrobacterium tumefaciens as a vector.


Moving from one point to another within a plant by either the xylem or phloem.

yeast two-hybrid system

A method for isolating pairs of proteins that interact via their DNA-binding and activation domains. Protein-protein interactions are commonly found in signal transduction cascades.