OLCreate: Glossary

Glossary

Browse the glossary using this index

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A

acquired resistance

Resistance to an antibiotic to which a bacterium is innately susceptible. It occurs when a bacterium acquires the ability to resist the actions of a particular antibiotic through either genetic mutation or horizontal gene transfer.

amino acid

The individual unit from which proteins are constructed.

antimetabolites

Chemicals that are structurally similar to natural metabolites but just different enough to interfere with normal cell function.

B

bactericidal

Antibiotic that kills bacteria.

bacteriophage

A virus that infects bacteria.

bacteriostatic

Antibiotics that stop or slow bacterial growth.

broad-spectrum

Antibiotics that affect (either kill, or stop reproducing) a wide range of bacteria: particularly, both Gram-positive and Gram-negative species.

C

chromosomes

DNA molecules containing some, or all, of the genetic information of an organism.

E

efflux pump

Transport proteins in the bacterial membrane that actively transport antibiotics out of the bacterial cell.

enzymes

Proteins that speed up (catalyse) chemical reactions in living organisms.

eukaryotes

One of the two main categories of living things (the other is prokaryotes). Eukaryotic organisms, including humans and animals, have cells containing nuclei and other membranous organelles.

G

gene

A sequence of DNA that encodes the amino acid sequence of a particular protein.

genetic mutations

Changes in the sequence of DNA due to either errors made while copying the DNA or environmental factors. Genetic mutations in genes can result in changes to the amino acid sequence encoded by the gene and may change the function of the resulting protein.

Gram-negative

Bacteria that do not retain crystal violet dye in the Gram-staining test.

Gram-positive

Bacteria with a thick peptidoglycan layer in their cell wall that is stained blue–purple by the Gram stain dye.

H

horizontal gene transfer

The process of transferring genetic information between two unrelated cells. It is the primary mechanism of spreading antibiotic resistance because it allows bacteria to spread antibiotic resistance genes rapidly between different species.

I

intrinsic resistance

The innate ability of a bacterial species to resist the action of antibiotic as a consequence of the bacteria’s structural or functional characteristics.

isolates

A bacterial strain separated from a mixed population of microbes such as those found in the soil or inside the gut.

M

metabolism

The chemical reactions in an organism that allow it to obtain the energy and nutrients it needs to grow and survive.

metabolites

The intermediates and products of metabolism.

N

narrow-spectrum

Antibiotics that only affect a small range of bacterial types.

P

peptidoglycan

A major component of bacterial cell walls. A large polymer, consisting of sugars and amino acids, that forms a mesh-like layer outside the bacterial cell membrane.

plasmid

A circular, non-chromosomal piece of DNA often carrying genes associated with a particular function, e.g. antibiotic resistance.

porin

A transmembrane protein complex that allows the movement of small molecules across the bacterial outer membrane.

prokaryotes

One of the two main categories of living things (the other is eukaryotes). Prokaryotic cells lack a nucleus, mitochondria and other membrane-bound organelles.

R

replication

The synthesis of an exact copy of a DNA molecule.

S

selective toxicity

The targeting of drugs to affect only the disease-causing, pathogenic organism and minimise damage to the host cells and commensal mico-organisms.

structural analogue

A compound having a structure similar to that of another compound but a different function.

T

transduction

A horizontal gene transfer mechanism in which plasmids are transferred from one bacterium to another, mediated by a virus.

V

vertical gene transfer

The transfer of genetic information from a parent to its offspring.

virus

An infectious agent that is approximately ten times smaller than a bacterium and cannot replicate outside a host cell. Viral infections cannot be treated with antibiotics.