Prokaryotes and the Domains of Life

Vocabulary review flashcards covering prokaryotic cell structures, classification, taxonomy, extremophiles, and reproductive mechanisms.

Prokaryote

A single-celled organism that lacks a nucleus and membrane-bound organelles, typically ranging in size from $0.1{-}5null\mu\text{m}$

Eukaryote

A unicellular or multicellular organism containing a true nucleus and membrane-bound organelles, typically ranging in size from $10{-}100\,\mu\text{m}$

Taxonomy Hierarchy

The classification system for all life, consisting of Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species

Domain Bacteria

A domain of prokaryotic organisms characterized by cell walls containing peptidoglycan and found nearly everywhere

Domain Archaea

A domain of prokaryotic organisms whose cell walls lack peptidoglycan, often found in extreme environments

Domain Eukarya

The domain comprising all eukaryotic organisms, divided into the kingdoms Protista, Fungi, Plantae, and Animalia

Protista

A kingdom of Eukarya consisting of microscopic or macroscopic, mostly unicellular organisms that can be autotrophs or heterotrophs

Fungi

A kingdom of Eukarya composed of unicellular or multicellular heterotrophic organisms with cell walls made of chitin

Plantae

A kingdom of Eukarya composed of multicellular autotrophic organisms with cell walls made of cellulose

Animalia

A kingdom of Eukarya composed of multicellular heterotrophic organisms that do not have cell walls

Peptidoglycan

A substance forming the cell walls of bacteria, which is absent in the cell walls of Archaea

Extremophiles

Organisms, primarily within Domain Archaea, that thrive in extreme environmental conditions

Thermophiles

Extremophiles that thrive in extreme temperatures

Acidophiles

Extremophiles that thrive in environments with extreme acidity

Methanogens

Extremophiles that produce methane and are commonly found deep in subterranean habitats

Halophiles

Extremophiles that thrive in extreme salt environments

Radioresistant

Organisms capable of surviving high levels of radioactivity

Flagella

Whip-like exterior structures on bacterial cells used for movement

Pili

Tubular extensions of the plasma membrane used to pass plasmids to other bacteria

Capsule

A protective outer coating that acts as a shield for a bacterial cell

Cell Wall

A strong, porous structure that provides protection and support to the cell

Plasmid

A small, circular piece of DNA separate from the main chromosome that carries a few genes

Gram Positive Bacteria

Bacteria with a thick peptidoglycan cell wall and outer capsule, which stain purple/violet and are more easily treatable with antibiotics

Gram Negative Bacteria

Bacteria with an inner plasma membrane, thin peptidoglycan cell wall, another outer plasma membrane, and outer capsule, which stain red/pink and are harder to treat with antibiotics

Heterotrophic

A nutritional strategy where organisms absorb nutrients from other organisms as parasites or decomposers

Photo Autotrophic

A nutritional strategy where organisms obtain energy directly from sunlight

Chemo autotrophs

Organisms that obtain energy by breaking down chemical substances, including archaebacteria and nitrogen-fixing bacteria on plant roots

Binary Fission

A form of asexual reproduction where a bacterial cell copies its circular DNA, elongates, and divides in the center into two identical daughter cells

Conjugation

The direct transfer of genetic material between two bacterial cells through physical contact via a pilus

Endospore

A thick, internal wall that encircles a prokaryote's DNA during unfavorable conditions, enabling the cell to lie dormant for extended periods