Prokaryotic Definitions

Vocabulary flashcards based on lecture notes about prokaryotes.

Anaerobic Respiration

A catabolic pathway in which inorganic molecules other than oxygen accept electrons at the “downhill” end of electron transport chains.

Biofilm

A surface-coating colony of one or more species of prokaryotes that engage in metabolic cooperation.

Capsule

A dense layer of polysaccharide or protein that surrounds the cell wall, protecting the cell and enabling it to adhere to substrates or other cells.

Chemoautotroph

An organism that obtains energy by oxidizing inorganic substances and needs only carbon dioxide as a carbon source.

Chemoheterotroph

An organism that requires organic molecules for both energy and carbon.

Commensalism

A +/0 ecological interaction that benefits one species but neither harms nor helps the other.

Conjugation

The direct transfer of DNA between two cells that are temporarily joined.

Decomposers

An organism that absorbs nutrients from nonliving organic material and converts them to inorganic forms; a detritivore.

Endospores

A thick-coated, resistant cell produced by some bacterial cells when they are exposed to harsh conditions.

Endotoxins

A toxic component of the outer membrane of certain gram-negative bacteria that is released only when the bacteria die.

Exotoxins

A toxic protein secreted by a prokaryote that produces specific symptoms, even if the pathogen is no longer present.

Extreme Halophile

An organism that lives in a highly saline environment.

Extreme Thermophile

An organism that thrives in hot environments (often 60-80°C or hotter).

Extremophile

An organism that lives in environmental conditions so extreme that few other species can survive there.

F Factor

The DNA segment that confers the ability to form pili for conjugation and associated functions required for the transfer of DNA from donor to recipient.

F Plasmid

The plasmid form of the F factor.

Fimbria

A short, hairlike appendage of a prokaryotic cell that helps it adhere to the substrate or to other cells.

Gram-Negative

Bacteria with a structurally complex cell wall containing less peptidoglycan; often more toxic.

Gram-Positive

Bacteria with a structurally simple cell wall containing more peptidoglycan; usually less toxic.

Heterocysts

A specialized cell that engages in nitrogen fixation in some filamentous cyanobacteria; also called a heterocyte.

Host

The larger participant in a symbiotic relationship, often providing a home and food source for the smaller symbiont.

Methanogens

An organism that produces methane as a waste product.

Mutualism

A +/+ ecological interaction that benefits individuals of both of the interacting species.

Nitrogen Fixation

The conversion of atmospheric nitrogen (N2) to ammonia (NH3).

Nucleoid

A non-membrane-enclosed region in a prokaryotic cell where its chromosome is located.

Parasite

An organism that feeds on the cell contents, tissues, or body fluids of another species (the host) while in or on the host organism.

Parasitism

A +/– ecological interaction in which the parasite benefits by feeding upon the host, which is harmed.

Pathogen

An organism or virus that causes disease.

Peptidoglycan

A type of polymer in bacterial cell walls consisting of modified sugars cross-linked by short polypeptides.

Photoautotroph

An organism that harnesses light energy to drive the synthesis of organic compounds from carbon dioxide.

Photoheterotroph

An organism that uses light to generate ATP but must obtain carbon in organic form.

Pilus

A structure that links one cell to another at the start of conjugation; also known as a sex pilus or conjugation pilus.

Plasmid

A small, circular, double-stranded DNA molecule that carries accessory genes separate from those of a bacterial chromosome.

Prokaryotes

An organism that has a prokaryotic cell; an informal term for an organism in either domain Bacteria or domain Archaea.

Protocells

An abiotic precursor of a living cell that had a membrane-like structure that maintained an internal chemistry different from that of its surroundings.

R plasmid

A bacterial plasmid carrying genes that confer resistance to certain antibiotics.

Ribozome

A complex of rRNA and protein molecules that functions as a site of protein synthesis in the cytoplasm.

Symbiont

The smaller participant in a symbiotic relationship, living in or on the host.

Symbiosis

An ecological relationship between organisms of two different species that live together in direct and intimate contact.

Taxis

An oriented movement toward or away from a stimulus.

Transduction

A process in which phages (viruses) carry bacterial DNA from one bacterial cell to another.

Transformation

A change in genotype and phenotype due to the assimilation of external DNA by a cell.