MICRO chapter 1

aseptic technique

a series of steps taken to prevent contamination of laboratory cultures and media

cell wall

relatively permeable structure located outside the cytoplasmic membrane and is a much stronger layer than the membrane itself

chemolithotropy

any metabolic process in which energy for growth is produced using only inorganic chemical compounds

chromosome

the structures that organize a cell’s genome

• DNA molecules that carries many genes

colony

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

contrast

The ability to resolve (differentiate) a cell or structure from its surrondings

culture

A collection of microbial cells grown using a nutrient medium

cytoplasm

aqueous mixture of macromolecules, small organic molecules, various inorganic ions and ribosomes

cytoplasmic membrane

permeability barrier that seperates the inside of a cell

diffrentiation

process by which cells are gentically identical become specialized and take on different structures or functions

domain

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

DNA replication

Process of copying a cell’s genetic blueprint before division so that each daughter cell recieves and identical set of genetic information

enrichment culture

a culture that employs highly selective laboratory methods for obtaining microoganisms from natural samples

enzyme

proteins that have catalytic activity, carry out reactions that supply energy and perform biosynthesis within the cell

eukarytoic

-contains a nucleus

-contains a membrane-bound nucleus and membrane-enclosed organelles

-larger and structurally more complex

evolution

genes in a population of cells change in sequence and frequency over time, leading to descent with modification

extremophiles

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

genome

fulll set of genes in a cell

gram-negative

a diffrerntial staining procedure that stains cells pink

gram-positive

a differential staining procedure that stains cells purple

gram stain

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

growth

an increase in cell number with time

gut microbiome

the microbial communities present in the animal gastrointestinal tract

horizontal gene transfer

the exchange of DNA between cells that are not in a director ancestor-descendant (vertical) relationship

• DNA from a donor cell is passed unidirectly to a recipient cell and becomes part of the recipient”s genome

intercellular communication

when cells release specific signaling molecules into their surrondings and neighboring cells detect these signals with receptors to change their behaviors

koch’s postulates

a set of criteria for providing that a given microoganism causes a given disease

macromolecules

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

magnification

the optical enlargement of an image

medium

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

metabolism

a process in which nutrients are acquired from the environment and transformed into new cellular materials and waste products

microbial community

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

microbial ecology

the study of the interaction of microorganisms with each other anf their environment

microorganism

life forms too small to be seen by the unaided human eye

morphology

the physical apperance of a cell as determines by cell shape

motility

allows cells to recolate in response to a environmental condition (movement)

nucleoid

a mass that is visible in the electron microscpe but is not enlosed by a membrane

organelle

membrane-enclosed cytoplasmic structures, which carry out particular functions

pathogen

a disease-causing microorganism

phylogenetic tree

a diagram that depicts the evolutionary history of an organism: consists of nodes and branches

phylogeny

the evolutionary history of organisms

plasmid

small, extra DNA molecules found in many Bacteria and Archaea in addition to their main chromosome.

prokaryotic

-Simple type of cell found in organisms

-few internal structures, lack a nucleus and membrane-bound organelles

-genetic material located in nucleoid region

-Bacteria and Archaea

pure culture

Contain cells from only a single type of microorganism and are of great value for the study of microogranisms

resolution

The ability to distinguish two adjacent objects as distinct and separate

ribosomal RNA

the types of RA found in the ribosome: some participate actively in protein synthesis

ribosome

structures responsible for protein synthesis

spontaneous generation

the hyothesis that living organisms can originate from nonliving matter

sterile

without the presence of living organisms

transcription

the process by which the information encoded in DNA sequences is copied into an RNA molecule

translation

the process where the information in an RNA molcule is used by a ribosome to synthesize a protein

nucleus

membrane-bound compartment found only in eukarytoic cells that contains the cell’s chromosomes