Microbiology Ch 1, 3, 4, and 5 Term Words (Nester's - A human perspective 8th ed)

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Domain

The highest level in biological classification. There are three domains: Bacteria, Archaea, Eukarya

Eukaryote

Organism composed of one or more eukaryotic cells; members of the domain eukarya are eukaryotes

Eukaryotic cell

cell type characterized by a membrane-bound nucleus

Prion

An acellular infectious agent consisting only of protein

Prokaryotic cell

Single-celled organism consisting of a prokaryotic cell; members of the domain bacteria, archaea are prokaryotes

Viroid

An acellular infectious agent consisting only of RNA

Capsule

a distinct, thick gelatinous material that surrounds some microorganisms

Chemotaxis

Movement of a cell towards or away from a certain chemical in the environment

Cytoplasmic membrane

A phospholipid bilayer embedded with proteins that surrounds the cytoplasm and defines the boundary of the cell

Endospore

An extraordinarily resistant dormant cell produced by some types of bacteria

Flagellum

A type of structure used for cell movement

Gram-negative bacteria

Bacteria that have a cell wall characterized by a thin layer of peptidoglycan surrounded by an outer membrane; when Gram stained, these cells are pink

Gram-positive bacteria

Bacteria that have a cell wall characterized by a thick layer of peptidoglycan; when Gram stained, these cells are purple

Lipopoly saccharide

Molecules that make up the outer layer of the outer membrane of Gram-negative bacteria

Peptidoglycan

A molecule that provides strength to the cell wall; it is found only in bacteria

Periplasm

The gel-like material that fills the region between the cytoplasmic membrane and the outer membrane of Gram-negative bacteria

Pili

Cell surface structures that allow cells to adhere to certain surfaces; some types are involved in a mechanism of DNA transfer

Plasmid

Extrachromosomal DNA molecule that replicates independently of the chromosome

Ribosome

Structures involved in protein synthesis

Transport system

mechanisms used to transport nutrients and other small molecules across the cytoplasmic membrane

Biofilm

polymer-encased community of microorganisms

chemically defined medium

a culture medium in which the exact chemicals; generally used only for specific experiments when nutrients must by precisely controlled

Complex medium

A culture medium with an ingredient that certain microorganisms proteins digests, extracts, or other ingredients that vary in their chemical composition

Differential medium

A culture medium with an ingredient that certain microorganisms change in a recognizable way; used to differentiate microbes based on their metabolic traits

Exponential (log) Phase

Stage in the growth curve during which cells divide at a constant rate; generation time is measured during this period of active multiplication

Focultative Anaerobes

Organisms that grow best if oxygen is present, but can also grow without oxygen

Generation Time

Time it takes for the number of cells in a population to double; doubling time

Obligate Aerobes

Organisms that have an absolute requirement for o2. They use aerobic respiration (micrococcus luteus)

Obligate Anaerobes

organisms that cannot multiply if oxygen is present

Plate count

Measures the number of viable cells in a sample by taking advantage of the fact that an isolated microbial cell on a nutrient agar plate will give rise to one colony

Pure culture

Population of organisms descended from a single cell

Selective medium

A culture medium with an ingredient that inhibits the growth of microorganisms making it easier to isolate the one being sought

Antiseptic

A disinfectant nontoxic enough to be used on skin

Aseptic technique

Procedures that help prevent the accidental introduction of unwanted microbes

Bactericide

Substance that kills bacteria

Bacteriostatic

Prevents the growth of, but does not kill bacteria

Disinfectant

A chemical that destroys many, but not all microbes

Pasteurization

Brief heating to reduce number of spoilage orgs, destroy pathogens, or disease causing microbes

Preservation

Inhibition of microbial growth to delay spoilage

Sterile

Free of all viable microbes including endospores and viruses

Sterilization

The destruction or removal of all microbes through physical or chemical means