Brooks Microbes Chapter 1

Motility

the movement of cells by some form of self-propulsion

Metabolism

all biochemical reactions in a cell

Cytoplasm

the fluid portion of a cell, enclosed by the cytoplasmic membrane

Koch's postulates

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

Eukaryotic

having a membrane-enclosed nucleus and various other membrane-enclosed organelles; cells of Eukarya

Pure culture

a culture containing a single kind of microorganism

Chemolithotrophy

a form of metabolism in which energy is generated from the oxidation of inorganic compounds

Cell wall

a rigid layer present outside the cytoplasmic membrane; it confers structural strength on the cell

Colony

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

Nucleoid

the aggregated mass of DNA that makes up the chromosome(s) of prokaryotic cells

Extremophiles

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

Horizontal gene transfer

the transfer of genes between cells through a process uncoupled from reproduction

Intercellular communication

interactions between cells using chemical signals

Differentiation

modification of cellular components to form a new structure, such as a spore

DNA replication

the process by which information from DNA is copied into a new strand of DNA

Enrichment culture technique

a method for isolating specific microorganisms from nature using specific culture media and incubation conditions

Genome

an organism's full complement of genes

Evolution

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

Domain

one of the three main evolutionary lineages of cells: the Bacteria, the Archaea, and the Eukarya

Culture

a collection of microbial cells grown using a nutrient medium

Microorganisms

an organism that is too small to be seen by the unaided human eye

Gram stain

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

Magnification

the optical enlargement of an image

Gram-positive

a bacterial cell whose cell wall consists chiefly of peptidoglycan; it lacks the outer membrane of gram-negative cells

Phylogeny

the evolutionary history of organisms

Gram-negative

a bacterial cell with a cell wall containing small amounts of peptidoglycan and an outer membrane

Resolution

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

Phylogenetic tree

a diagram that depicts the evolutionary history of organisms

Ribosomal RNA (rRNA)

the types of RNA found in the ribosome

Prokaryotic

lacking a membrane-enclosed nucleus and other organelles; cells of Bacteria or Archaea

Microbial ecology

the study of microorganisms in their natural environments

Cytoplasmic membrane

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

Macromolecules

a polymer of monomeric units, for example proteins, nucleic acids, polysaccharides, and lipids

Organelle

a bilayer-membrane-enclosed structure such as the mitochondrion, found in eukaryotic cells

Sterile

free of all living organisms (cells) and viruses

Translation

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

Ribosomes

a structure composed of RNAs and proteins upon which new proteins are made

Contrast

the ability to resolve a cell or structure from its surroundings

Pathogen

a disease-causing microorganism

Enzyme

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

Spontaneous generation

the hypothesis that living organisms can originate from nonliving matter

Microbial community

two or more populations of cells that coexist and interact in a habitat

Nucleus

a membrane-enclosed structure in eukaryotic cells that contains the cell's DNA genome

Aseptic technique

the manipulation of sterile instruments or culture media in such a way as to maintain sterility

Medium (plural, media)

in microbiology, the liquid or solid nutrient mixture(s) used to grow microorganisms

Growth

in microbiology, an increase in cell number with time

Plasmid

an extrachromosomal genetic element that is not essential for growth

Transcription

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

Gut microbiome

the microbial communities present in the animal gastrointestinal tract