Introduction to Prokaryotic Cells – Chapter 3 (Microbiology: Basic and Clinical Principles, 2nd Edition)

Vocabulary flashcards covering key concepts about prokaryotic cell structure, classification, and physiology from Chapter 3.

Prokaryotic cells

Cells that lack a membrane-bound nucleus and membrane-bound organelles; typically unicellular and include the domains Archaea and Bacteria.

Archaea

One of the two prokaryotic domains; distinct from Bacteria; often found in extreme environments.

Bacteria

One of the two prokaryotic domains; distinct from Archaea; commonly associated with many human pathogens.

Eukarya

Domain that comprises eukaryotic organisms with membrane-bound organelles and a nucleus.

Monomorphic

Bacteria that have one consistent shape.

Pleomorphic

Bacteria that can take on several shapes, aiding survival and transmission.

Bacilli

Rod-shaped bacteria (singular: bacillus).

Cocci

Spherical bacteria (singular: coccus).

Vibrio

Comma-shaped bacteria.

Spirillum

Spiral-shaped bacteria.

Spirochete

Corkscrew-shaped bacteria capable of spiral motion.

Stella

Star-shaped bacteria.

Coccobacillus

An oval/short rod-shaped bacterium.

Diplococci

Cocci arranged in pairs.

Streptococci

Cocci arranged in chains.

Staphylococci

Cocci arranged in grapelike clusters.

Diplobacilli

Bacteria arranged in paired bacilli.

Streptobacilli

Chains of bacilli.

Palisade

Clusters of bacilli arranged like a fence.

Binary fission

Asexual reproduction that results in two genetically identical daughter cells; steps include DNA replication, cell growth, chromosome movement to ends, septum formation, and separation.

Plasma membrane

Thin, flexible phospholipid bilayer that acts as a selective barrier and hosts metabolic processes.

Membrane proteins

Proteins in the membrane that function as transporters, anchors, receptors, or enzymes; can comprise about half of membrane mass.

Selective permeability

Property of allowing certain substances to diffuse freely while requiring transporters for others.

Membrane fluidity

The lipid bilayer is fluid; temperature and fatty acid composition influence fluidity.

Archaea vs Bacteria membranes

Bacteria typically have linear fatty acids; Archaea have long-branched fatty acids and some possess lipid monolayers in extreme heat.

Cell wall

Rigid layer outside the plasma membrane; bacteria use peptidoglycan, archaea use pseudopeptidoglycan.

Gram staining

Classifies bacteria by cell wall structure: Gram-positive with thick peptidoglycan and no outer membrane (purple); Gram-negative with thin peptidoglycan and an outer membrane containing LPS (pink).

Outer membrane (Gram-negative)

Outer membrane containing lipopolysaccharide (LPS) and porins; acts as a barrier to many substances.

Lipopolysaccharide (LPS)

LPS is an endotoxin component of the Gram-negative outer membrane; contributes to permeability and immune activation.

Lipid A

Endotoxin component of LPS found in Gram-negative bacteria.

Teichoic acids

Components of Gram-positive cell walls that help stabilize the wall, regulate shape, transport cations, and assist division.

Acid-fast staining

Staining method that detects mycolic acid in cell walls (waxy lipids); acid-fast bacteria include Nocardia and Mycobacterium and stain red/pink with slow growth.

Mycolic acid

Waxy lipid in acid-fast cell walls contributing to slow growth and resistance to decolorization.

Mycoplasma

Bacteria that lack a cell wall; have a sterol-enriched plasma membrane and are often pleomorphic; some exist as intracellular organisms.

L-forms

Bacteria that have lost their cell wall; can be resistant to stresses and may persist in hosts.

Endospores

Metabolically inactive, highly resistant structures enabling survival under harsh conditions; formed by certain Bacillus, Clostridium, and Clostridioides species.

Sporulation

Process of endospore formation, including DNA copying, spore coat formation, layered protection, and release.

Nucleoid

Region in prokaryotes where a single circular chromosome resides; not bounded by a membrane.

Ribosomes (70S)

Ribosomes in prokaryotes composed of 50S and 30S subunits; synthesize proteins.

Cytoskeleton

Protein filaments in prokaryotes that provide structure and support.

Inclusion bodies

Storages of substances within prokaryotes; examples include carboxysomes (carbon fixation) and magnetosomes (magnetite).

Flagella

Filament-like structures made of flagellin used for motility; rotate via a basal body anchored in the cell wall.

Run and tumble

Pattern of movement where cells run in one direction and then tumble to change direction.

Chemotaxis

Movement toward or away from chemical stimuli.

Phototaxis

Movement toward or away from light.

Aerotaxis

Movement in response to oxygen levels.

Flagella arrangements

Monotrichous (one flagellum), Lophotrichous (tuft at one pole), Amphitrichous (flagella at both poles), Peritrichous (flagella over the surface).

Periplasmic flagella (axial filaments)

Flagella located between the plasma membrane and cell wall that enable spirochetes to move with a corkscrew motion.

Fimbriae

Short, bristle-like structures that help bacteria adhere to surfaces and form biofilms; common in Gram-negative bacteria.

Pili

Longer, thicker appendages used for adhesion and genetic transfer via conjugation.

Glycocalyx

Sticky carbohydrate-rich layer; promotes adherence and protects against desiccation and some antibiotics; slime layer is unorganized, capsule is well organized.

Nucleoid vs cytoplasm distinction

Nucleoid contains the circular chromosome; cytoplasm contains cytosol and cellular processes.