Prokaryotes: Bacteria and Archaea

This set of flashcards provides essential vocabulary and definitions related to prokaryotes, specifically focusing on bacteria and archaea.

Prokaryotes

Organisms defined by the absence of a membrane-bound nucleus and organelles; include Bacteria and Archaea.

Gram-negative bacteria

Bacteria that do not retain the crystal violet stain used in the Gram staining method, characterized by a thin peptidoglycan layer.

Gram-positive bacteria

Bacteria that retain the crystal violet stain used in the Gram staining method, characterized by a thick peptidoglycan layer.

Phylogenetic tree

A diagram that shows the evolutionary relationships among various biological species based on similarities and differences in their physical or genetic characteristics.

Deeply branching bacteria

Bacteria that are the closest living relatives of the earliest living organisms on Earth.

Autotrophic

Organisms that can produce their own food from sunlight (photoautotroph) or from chemical energy (chemoautotroph).

Chemoautotroph

An organism that derives energy from the oxidation of inorganic compounds and uses carbon dioxide as a carbon source.

Hyperthermophilic

Organisms that thrive at extremely high temperatures, typically above 80°C.

Nitrogen-fixing bacteria

Bacteria that convert atmospheric nitrogen (N₂) into ammonia (NH₃), making nitrogen available for use by living organisms.

Obligate intracellular parasite

An organism that can only reproduce inside the cells of a host.

Endospores

A resilient form of bacteria that can withstand extreme conditions; important for pathogenicity and food spoilage.

Extremophiles

Microorganisms that thrive in extreme environmental conditions, such as high salinity, temperature, or acidity.

Symbiotic relationship

A close interaction between two different biological species, often benefiting both organisms.

Cocci

Spherical-shaped bacteria.

Bacilli

Rod-shaped bacteria.

Filamentous bacteria

Bacteria that form long, thread-like structures.

Pleomorphic

Organisms that can alter their shape and size in response to environmental conditions.

Anoxygenic photosynthetic bacteria

Bacteria that perform photosynthesis without producing oxygen, often using sulfur or organic compounds as electron donors.

Oxygenic photosynthetic bacteria

Bacteria that produce oxygen as a byproduct of photosynthesis, using water as an electron donor.

Halophiles

Extremophiles that thrive in high salt concentrations.

Thermophiles

Extremophiles that grow best at high temperatures, typically above 45°C.

Acidophiles

Extremophiles that thrive in acidic environments, often at a pH below 3.

Methanogens

Anaerobic microbes that produce methane as a metabolic byproduct.

Mycolic acids

Long-chain fatty acids found in the cell wall of mycobacteria, contributing to their virulence and drug resistance.

Chlamydia

A genus of bacteria that are obligate intracellular parasites and do not contain peptidoglycan in their cell walls.

Spirochetes

A phylum of bacteria characterized by their spiral shape and unique motility.

Plasmids

Small, circular, double-stranded DNA molecules found in bacteria that can replicate independently of chromosomal DNA.