Lab methods

A glossary of biotechnology methods and terms

Biotechnology borrows words from biology, chemistry, agriculture and engineering. This glossary gathers the terms used most often across the guide, each in a sentence or two of plain language. Where a definition draws on a public reference, the source is named.

Genes, DNA and proteins

Amino acid: One of the small building blocks that are joined in chains to make peptides and proteins. The MedlinePlus Genetics page What are proteins and what do they do? notes that 20 different types can be combined to make a protein.
DNA: The molecule that carries an organism's genetic instructions, written as a sequence of four chemical letters.
Gene: A stretch of DNA that carries the instructions for making a particular product, most often a protein.
Genetic engineering: The NIH Talking Glossary of Genomic and Genetic Terms defines genetic engineering, also called genetic modification, as a process that uses laboratory-based technologies to alter the DNA makeup of an organism, which may involve changing a single base pair, deleting a region of DNA or adding a new segment.
Recombinant DNA: DNA formed in the laboratory by bringing together genetic material from more than one source, creating a sequence not otherwise found in the genome, as Wikipedia's article on recombinant DNA explains. It is the basis of producing proteins from cloned genes.
Protein: A large molecule made of one or more long chains of amino acids folded into a specific shape. Proteins do most of the work in cells, as MedlinePlus explains.
Peptide: A short chain of amino acids linked by peptide bonds. Wikipedia's article on the peptide notes that longer chains are polypeptides and that those of 10,000 daltons or more are called proteins.
Enzyme: A protein that speeds up a particular chemical reaction without being used up. Amylases, xylanases and proteases are enzymes that break down starch, plant fibre and proteins respectively.
Pseudogene: A copy of a gene that has lost its ability to make a working product, like the broken urate oxidase gene in humans.

Reading and comparing DNA

PCR (polymerase chain reaction): The NIH glossary entry on PCR describes it as a laboratory technique for rapidly producing millions to billions of copies of a specific segment of DNA so it can be studied in detail.
Primer: A short synthetic piece of DNA that marks the start of the segment to be copied in PCR.
Molecular marker: A fragment of DNA associated with a particular location in the genome, used to identify a sequence in a pool of unknown DNA, according to Wikipedia's article on the molecular marker. Breeders use markers to follow useful traits.
Marker-assisted selection: Choosing plants or animals for breeding by testing their DNA for markers linked to a trait, rather than waiting for the trait to show.
Quantitative trait: A characteristic, such as salt tolerance or yield, that varies by degree and is influenced by many genes, each with a modest effect.

Cells, cultures and vessels

Culture medium: A solid, liquid or semi-solid designed to support the growth of microorganisms or cells, as Wikipedia's article on the growth medium defines it. Agar plates and nutrient broths are the most common kinds for microbes.
Agar: A jelly-like substance from seaweed used to set culture media so that microbes can be grown on a solid surface.
Defined medium: A medium in which the quantity of every ingredient is known, as opposed to an undefined medium containing complex extracts.
Inoculum: The small quantity of living organisms deliberately introduced into a medium to start a culture.
Colony: A visible spot of microbial growth on a solid medium, typically descended from a single cell.
Strain: A genetic variant or line within a species, such as a particular isolate of a bacterium with its own properties.
Cell line: A population of cells that can be grown continuously in culture, such as the Chinese hamster ovary lines used to make proteins.
Fermentation: In industrial biotechnology, any large-scale growth of microorganisms to make a product, whether or not oxygen is present.
Submerged fermentation: Growing microbes suspended in a liquid medium, usually in stirred tanks.
Solid-state fermentation: Growing microbes on a moist solid, such as bran, with little or no free water.
Bioreactor: Any manufactured device or system that supports a biologically active environment, often a cylindrical stainless-steel vessel, as Wikipedia's article on the bioreactor explains.
Secondary metabolite: A compound made by an organism that is not strictly needed for growth, such as many microbial pigments.

Keeping things clean

Sterile: Free of all living organisms, including spores.
Sterile technique: The set of working habits used to handle cultures without letting other organisms in, such as working near a clean airflow and keeping containers closed.
Autoclave: A pressurised steam chamber used to sterilise media, glassware and waste; it works on the same principle as a pressure cooker.

Plants in culture

Plant tissue culture: Techniques for growing plant cells, tissues or organs under sterile conditions on a nutrient medium of known composition, as defined in Wikipedia's article on plant tissue culture.
Explant: The piece of plant tissue, such as a shoot tip, taken from a parent plant to start a culture.
Meristem: A zone of actively dividing cells at the tip of a shoot or root, from which new growth comes.
Micropropagation: Rapid multiplication of plants from small pieces of tissue in sterile culture to give many identical plants.
Hardening off: Gradually accustoming plants raised in closed containers to open air, lower humidity and soil.

Environment and agriculture

Bioremediation: The use of living organisms, or their products, to remove or neutralise pollutants in soil, water or air.
Biological control: Managing pests, weeds or plant diseases by using other organisms, such as predators, parasites or competing microbes.
Antagonist: In biological control, an organism that suppresses a pathogen by competing with, inhibiting or attacking it.
Pathogen: An organism that causes disease in a host.
Salinisation: The build-up of salts in soil, whether from natural processes or from irrigation.

Medicines and delivery

Biologic: A medicine made in, or extracted from, living sources, including proteins made from recombinant DNA.
Route of administration: The way a substance is introduced into the body, for example oral or intravenous.
Bioavailability: The fraction of an administered substance that reaches the general circulation.
Modified release: A formulation designed to release its contents after a delay, over a prolonged period or at a particular site, rather than all at once.
Emulsion: A mixture of two liquids that do not normally mix, with droplets of one dispersed through the other; a nanoemulsion has extremely small droplets.