Adhesins: surface appendages that facilitate adhesion or adherence of bacterial cells to other cells or to surfaces
Aminoacids: monomeric units of proteins mostly consisting of carbon, hydrogen, oxygen and nitrogen atoms
Antibiotic: a chemical that inhibits the growth of microorganisms or kills them
Antimicrobial resistance: the acquired ability of a microorganism to grow in the presence of an antimicrobial drug to which the microorganism is originally sensitive
Archaea: phylogenetically related prokaryotes distinct from Bacteria
Bacteraemia: bacterial shedding into the bloodstream in large numbers after bacteria grow extensively in tissues
Bacillus (pl. bacilli): A bacterium with a cylindrical, rod shape
Bacteria: all prokaryotes that are not members of the domain Archaea
Bacteriophage: a virus that infects prokaryotic cells
Biofilm: communities of bacterial cells attached to a surface and encased in adhesive polysaccharides excreted by the cells
Carbohydrate: organic sugars, containing carbon, hydrogen and oxygen atoms, the most abundant one being the glucose
Capsid: the protein coat of a virus
Capsule: a polymer coat consisting of a dense, well-defined polysaccharide or protein layer closely surrounding a cell
Cell: the fundamental unit of living matter
Cell membrane: the permeability barrier of the cell, separating the cytoplasm from the environment; consists of lipid and protein
Cell wall: a structural layer outside the cell membrane giving the cell its rigidity and acting as a filtering mechanism
Chloroplast: the chlorophyll-containing organelle of photosynthetic eukaryotes
Chromosome: compact, organized state of DNA carrying genes essential to cell function
Coccus (pl. cocci): A spherical-shaped bacterium
Commensalism: a relationship between different species organisms of which one benefits from the relationship without harming the other
Cytoplasm: the fluid portion of a cell, bounded by the cell membrane but excluding the nucleus (if present)
Cytoplasmic membrane: thin structure that completely surrounds the cell
DNA: stands for deoxyribonucleic acid, the hereditary genetic information of cells and some viruses essential to produce progeny
Domain: the highest level of biological classification
Ecology: the study of organisms in their natural environments
Ecosystem: organisms plus their non-living environment
Endospore: a highly heat-resistant, thick-walled, differentiated cell produced by certain gram-positive Bacteria
Enrichment culture: a method for isolating microorganisms from nature using specific culture media and incubation conditions
Endotoxin: cell-bound or intracellular toxic molecules that are released in large amounts only when cells are lysed
Enterotoxin: an exotoxin that acts on the small intestine, generally causing massive secretion of fluid into the intestinal lumen, leading to vomiting and diarrhea
Enzymes: protein catalysts that speed up chemical reactions
Epidemic: a disease occurring in an unusually high number of individuals in a population at the same time
Exotoxin: proteins released extracellularly as the organism grows and which may cause damage in regions far removed from the site of microbial growth
Eukaryote: a cell having a membrane-bound nucleus and usually other organelles
Evolution: change in a line of descent
Fever: an abnormal increase in body temperature
Fimbriae: short, filamentous protein structures on the surface of bacterial cells, involved in attachment
Flagellum: a long, thin cellular appendage capable of rotation and responsible for swimming and swarming movements in prokaryotic cells
Fungi: eukaryotic microorganisms that contain rigid cell walls
Gene: segment of DNA that encodes a full protein or regulatory RNA molecules essential for cell function
Genome: whole set of genes of a cell or a virus
Glycosidic bond: a type of bond that links sugar units
Gram-negative: a prokaryotic cell whose cell wall contains relatively little peptidoglycan but contains an outer membrane composed of lipopolysaccharide, lipoprotein, and other complex macromolecules
Gram-positive: a prokaryotic cell whose cell wall consists chiefly of peptidoglycan and lacks the outer membrane of gram-negative cells
Habitat: the location in an environment where a microbial population resides
Homeostasis: the biological process by which conditions (temperature, blood sugar level etc.) are controlled to maintain levels that are beneficial for the body
Immunity: the ability of an organism to resist infection
Immunocompromised (immunodeficient): having dysfunctional or completely nonfunctional immune system
Inflammation: a nonspecific reaction to harmful agents such as toxins and pathogens
Lipid: glycerol bonded to fatty acids or other molecules such as phosphate
Lipopolysaccharide: building block of the additional layer of cell wall in Gram-negative bacteria called the outer membrane, not constructed solely of phospholipid as the cytoplasmic membrane but of polysaccharide and protein
Lysozyme: a naturally occurring enzyme found in bodily secretions of humans such as tears, saliva, and mothers’ milk
Metabolism: all biochemical reactions in a cell
Macromolecule: the collective name given to the four chemical components making up the cell: proteins, nucleic acids, lipids and polysaccharides
Microorganism: a microscopic organism consisting of a single cell or cell cluster, including the viruses
Microscope: a magnifying instrument used to look at objects that are too tiny to be seen by the naked eye
Mitochondrion: the respiratory organelle of eukaryotic organisms
Molds: filamentous fungi
Monomer: a building block of a polymer
Monotrichous: flagellum located at one end of the cell (trichous means ‘hair’
Morphology: cell shape
Motility: the property of movement of a cell under its own power
Multidrug resistance: the acquired resistance of a microorganism to many antimicrobial drugs
Mutation: a permanent and inheritable alteration of the nucleotide sequence of the genome
Nucleic acid: polymers of nucleotides found in a cell
Nucleoid: the aggregate form that bacterial chromosome is stored as
Nucleotide: a nitrogen base(adenine, guanine, cytosine, thymine, or uracil), a molecule of phosphate, and a sugar, either ribose (in RNA) or deoxyribose (in DNA) grouped together
Nucleus: a membrane-enclosed structure that contains the chromosome in eukaryotic cells
Organelle: a unit membrane-enclosed structure present in the cytoplasm of eukaryotic cells
Opportunistic pathogen: an infectious microorganism that is normally harmless or commensal but takes advantage of an opportunity not normally available, such as a host with a weakened immune system
Outbreak: the occurrence of a large number of cases of a disease in a short period of time
Pandemic: a worldwide epidemic
Pathogen: a disease-causing microorganism
Periplasm: a gel-like region between the outer surface of the cytoplasmic membrane and the inner surface of the lipopolysaccharide layer of gram-negative Bacteria
Peritrichous: flagella located in many places around the surface of the cell (peri means ‘around’, trichous means ‘hair’)
Peptide: aminoacids grouped together
Peptidoglycan: a thin sheet composed of two sugar derivatives and a small group of aminoacids, primarily responsible for the strength of the cell wall
Phenotype: all the observable characteristics of an individual
Phospholipid: lipids containing a phosphate group and having a structural role in the cytoplasmic membrane
Photosynthesis: the series of reactions in which energy is produced by light-driven reactions and carbondioxide is fixed into cell material
Phylogeny: the evolutionary relationships between organisms
Physiology: pertinent with the normal functioning of an organism
Pili: protein structure found in few numbers on the cell surface of bacteria and involved in attachment and exchange of genetic material
Plague: an endemic disease in rodents caused by the bacterium Yersinia pestis that is occasionally transferred to humans through the bite of a flea
Plasma membrane: the same as cell membrane
Plasmid: an extrachromosomal genetic element nonessential for growth, usually arranged in a circular fashion
Polymer: a chemical compound formed from repeating units called monomers by polymerization
Polypeptide: molecule of many aminoacids linked via peptide bonds
Polysaccharide: a long chain of carbohydrates connected by glycosidic bonds, primarily present in the cell wall
Porin: protein present in the outer membrane Gram-negative bacteria, forming small membrane holes
Prokaryote: a cell lacking a membrane-enclosed nucleus and other organelles
Protein: a group of peptides that form a molecule of specific biological function
Proteome: all the proteins present in a cell, tissue or organism at any one time
Protozoa: unicellular eukaryotic microorganisms that lack cell walls
Pure culture: a culture containing a single kind of microorganism
Quorum sensing: bacterial cell-cell communication mechanism
Ribosome: a cytoplasmic particle that is part of the protein-synthesizing machinery of the cell
RNA: stands for ribonucleic acid, the building blocks of proteins in the form of messenger RNA, transfer RNA, and ribosomal RNA
Slime molds: eukaryotic microorganisms that lack cell walls and that aggregate to form fruiting structures
Spirilla: rod-shaped bacteria twisted into spirals
Spirochetes: tightly coiled bacteria
Spontaneous generation: the hypothesis that living organisms can originate from non-living matter
Sterile: absence of all living organisms and viruses
Swarming motility: coordinated, multicellular translocation of bacteria on semi-solid surfaces
Toxin: a microbial protein endowed with the capacity of inducing host specific disease-associated physiological effects
Virulence: the relative ability of a pathogen to cause disease
Virus: a major class of microorganisms with packaged RNA or DNA that are not cells and can only reproduce inside living cells
Yeasts: unicellular fungi