Glossary of Biological Terms

aerobe An organism which needs molecular oxygen for its metabolism.

agar A jelly-like substance obtained from seaweed (red algae) used to help solidify nutrient media for growing microorganisms.

anaerobe An organism which cannot grow if molecular oxygen is present; strict anaerobes are killed by oxygen, facultative anaerobes will grow if oxygen is present but can also grow if oxygen is absent.

antibiotic A chemical produced by microorganisms, such as bacteria and moulds that, in dilute solution, can kill or inhibit the growth of other microorganisms.

antibody A protein produced by B lymphocytes of the immune system. Antibodies are very specific and help defend the body against pathogens and foreign molecules by binding to antigens and bringing about their destruction.

antigen A molecule that is recognised and bound by a specific antibody.

apoptosis A kind of cellular self-destruction that demands energy and protein synthesis for its occurrence.

artificial selection The purposeful breeding of certain traits over others.

autotroph An organism that is able to synthesise the organic materials it requires from inorganic substances in its environment.

biotechnology The application of living organisms, or substances made from them, to make products of value to humans.

capsid The protein coat of a virus.

cell A very small unit of living matter.

cell culture Growing cells or tissues in a laboratory, or on an appropriate nutrient medium.

chemoautotroph An organism which uses carbon dioxide as its sole source of carbon and inorganic chemicals as its source of energy.

chitin A tough resistant polysaccharide which is a component of some fungal cell walls.

class The second highest group into which animals and plants are divided, below a Phylum and including several orders.

clone A group of genetically identical organisms or cells which are all descended asexually from the same individual.

coccus (plural cocci) A sphere-shaped bacterium.

dry Without moisture.

environment The natural conditions, eg land, air and water, in which people, animals and plants live.

eukaryotic Cells containing a true nucleus, with a nuclear membrane and membrane-bound organelles.

evolution The scientific theory according to which types of animals and plants change gradually over long periods of time through a process known as natural selection to become better adapted to their environment.

family A group of related animals, plants, etc.

fermentation The extraction of energy from organic products without the involvement of oxygen. Or The use of microorganisms or enzymes extracted from microorganisms to carry out a wide variety of chemical reactions, which may or may not be anaerobic.

flagellum (plural flagella) A fine, long, whip-like organelle which protrudes from the cell surface. Used in locomotion and feeding they are common in some protoctista where they have a 9+2 arrangement of microtubules in cross section. They are also found as thread-like organelles in some bacteria, also used in locomotion, they have a much simpler structure in prokaryotes, being a rigid hollow cylinder of protein with a rotating base which propels the cell along.

fungi A kingdom of eukaryotic, mainly multicellular organisms which lack chlorophyll.

gene A length of DNA which codes for the production of a particular protein.

genetic engineering The application of methods using recombinant DNA to give new genetic traits to an organism by introducing new genes into its cells.

genome The complete set of genes present in an organism.

genus (plural genera) A group of animals or plants within a family, often itself divided into several species.

grow 1 to increase in size or quantity; to become greater; 2 to develop into a mature or an adult form.

growth The process of growing; development.

heterotroph An organism which requires organic compounds as its carbon and energy source.

host An animal or a plant on which another animal or plant lives.

hypothesis (plural hypotheses) An idea or a suggestion that is based on known facts and is used as a basis for reasoning or further investigation.

immunization A process rendering a host immunity to a disease.

in vitro Latin for ‘in glass’. This term refers to biological processes carried out outside a living organism, for example, in a test tube.

inoculation The transfer of microorganisms from one source to another, e.g. transferring bacteria from a broth culture on to a sterile agar plate, or from a starter culture into a fermenter containing sterile medium.

interferons A group of proteins which are active in the immune system. They fight viral infections and stimulate the cell-killing abilities of some immune cells. They are being tested for use in cancer therapy and in the treatment of AIDS and other viral diseases.

limb 1 A leg, an arm or a wing; 2 a large branch of a tree.

lymphocyte A type of white blood cell (granulocyte) for example B and

T cells.

magnify To make something appear larger, especially by using a lens or microscope.

meristem culture Plant cells cultured from the undifferentiated meristematic tissue from which new cells arise.

mesophile An organism which has an optimum growth between 20*C and 40*C, including most human pathogens.

microscope An instrument for making very small objects appear larger, especially for scientific study.

muscle A piece of elastic body tissue that can be tightened or relaxed to produce movement.

mycelium Composed of a mass of fungal hyphae tangled together.

natural selection The process by which heritable advantageous traits become more common in successive generations, and unfavourable traitsbecome less common.

nutrient A substance that helps a living thing to grow.

order A group of related animals or plants below a class and above a family.

pathogen A microorganism or virus that causes disease.

phylum (plural phyla) A major group to which animals or plants belong.

plant A living thing that grows in the earth and usually has a stem, leaves and roots.

plasmid A small, usually circular molecule of DNA that occurs in bacteria but is not part of the bacterial chromosome. Plasmids have been used as cloning vectors to transfer genes between species.

Prokaryotae A kingdom of microscopic, mainly unicellular microorganisms, including bacteria. Their DNA is circular, naked, and not situated inside a nuclear membrane. Prokaryotic cells also lack membrane-bound organelles, such as mitochondria.

Protoctista A kingdom of microscopic, eukaryotic organisms. They may be unicellular or multicellular, and mainly show sexual reproduction. It is a diverse group including heterotrophic and photosynthetic organisms.

protoplasts Plant cells that have had their rigid cellulose cell walls removed. They are fused to produce cell hybrids and used as targets for gene transfer in plant genetic engineering.

recombinant DNA A DNA molecule that has been formed by joining together segments of DNA from two or more sources.

root The part of a plant that grows under the ground, absorbing water and minerals.

sample One of a number of things, one part of a whole, that can be examined in order to seewhat the rest is like; a specimen.

sap The liquid in a plant that carries food to all parts of it.

seed The part of a plant from which a new plantof the same kind can grow.

species A group of animals or plants within a Genus. Members of a species are able to breed with each other but usually not with other species.

stem The main long thin part of a plant above the ground, or any of the smaller parts growing from this, from which the leaves or flowers grow.

substrate A compound acted on by an enzyme and converted to a product.

vector In biotechnology, a vector is a DNA molecule which is used to transfer genes into cells; usually this is plasmid or viral DNA.

vegetation Plants in general; plants found in a particular environment.

viable Live; capable of reproducing.

virology The study of viruses and some other virus-like agents.

virus A particle containing a nucleic acid core, either DNA or RNA, surrounded by a protein coat called a capsid. Viruses are obligate parasites that reproduce by entering cells and taking over the cell`s own protein synthesizing mechanisms.

vital Connected with or essential to life.