PDF Brocks Chapter 1

Comprehensive vocabulary flashcards generated from Chapter 1: The Microbial World.

Microorganism

A life form too small to be seen by the unaided human eye, diverse in form and function, inhabiting every environment on Earth that supports life.

Microbial culture

A collection of cells that have been grown in or on a nutrient medium.

Medium

A liquid or solid nutrient mixture that contains all of the nutrients required for a microorganism to grow.

Growth

In microbiology, the increase in cell number as a result of cell division.

Colony

A macroscopically visible population of cells growing on a solid medium, arising from a single cell.

Cytoplasmic membrane

A semipermeable barrier that separates the cell interior (cytoplasm) from the environment.

Cytoplasm

The fluid portion of a cell enclosed by the cytoplasmic membrane, containing an aqueous mixture of macromolecules, small organic molecules, inorganic ions, and ribosomes.

Ribosome

A cytoplasmic particle composed of ribosomal RNA and protein, whose function is to synthesize proteins in all cells.

Cell wall

A relatively permeable, rigid layer located outside the cytoplasmic membrane that confers structural strength on the cell.

Eukaryotic

Having a membrane-enclosed nucleus and various other membrane-enclosed organelles; cells belonging to the domain Eukarya.

Organelle

A membrane-enclosed structure, such as the mitochondrion or nucleus, found in eukaryotic cells.

Prokaryotic

Lacking a membrane-enclosed nucleus and other organelles; characteristic of cells belonging to Bacteria and Archaea.

Genome

The total complement of genes contained within a cell or virus.

Nucleoid

The aggregated mass of DNA that makes up the chromosome(s) of a prokaryotic cell, not enclosed by a membrane.

Plasmid

An extrachromosomal genetic element, usually circular, that is not essential to the cell but often confers special properties such as antibiotic resistance.

Metabolism

All biochemical reactions occurring in a cell, divided into catabolism and anabolism.

Enzyme

A protein (or in some cases an RNA) catalyst that functions to speed up chemical reactions.

Transcription

The synthesis of an RNA molecule complementary to one of the two strands of a double-stranded DNA molecule.

Translation

The synthesis of protein by a ribosome using the genetic information in a messenger RNA as a template.

Motility

The movement of cells by some form of self-propulsion.

Differentiation

Modification of cellular components to form a new specialized structure, such as a spore.

Horizontal gene transfer

The unidirectional transfer of genes between cells through a process uncoupled from reproduction.

Evolution

A change over time in gene sequence and frequency within a population of organisms, resulting in descent with modification.

Morphology

The physical appearance of a cell as determined by cell shape, such as rod, coccus, or spirillum.

Coccus

A cell that is spherical or ovoid in morphology.

Rod (Bacillus)

A cylindrically shaped cell.

Spirillum

A rigid, spiral-shaped cell.

Spirochete

A flexible, spiral-shaped bacterium.

Extremophiles

Microorganisms that inhabit environments characterized by extremes of temperature, pH, pressure, or salinity.

Pathogen

A disease-causing microorganism.

Gram stain

A differential staining procedure that stains cells either purple (gram-positive cells) or pink (gram-negative cells).

Gram-positive

A bacterial cell whose cell wall consists chiefly of peptidoglycan, lacking an outer membrane, staining purple in a Gram stain.

Gram-negative

A bacterial cell with a cell wall containing small amounts of peptidoglycan and an outer membrane, staining pink/red in a Gram stain.

Chemolithotrophy

A form of metabolism in which energy is generated from the oxidation of inorganic compounds and carbon is obtained typically from $\text{CO}_2$.

Enrichment culture

A culture that employs highly selective laboratory methods for obtaining specific microorganisms from natural samples.

Aseptic technique

A series of steps taken to prevent contamination of laboratory cultures and media.

Pure culture

A culture containing a single kind of microorganism.

Koch's postulates

A set of criteria for proving that a given microorganism causes a given disease.

Sterile

Free of all living organisms (cells) and viruses.

Magnification

The optical enlargement of an image.

Resolution

The ability to distinguish two objects as distinct and separate when viewed under the microscope.

Phylogeny

The evolutionary history of organisms.

Phylogenetic tree

A diagram that depicts the evolutionary history of an organism or group of organisms, consisting of nodes and branches.