Chapter 4: A Survey of Prokaryotic Cells and Microorganisms

Vocabulary flashcards covering key terms related to prokaryotic cells and their structures and functions as presented in the lecture notes.

Prokaryotic cell

A cell lacking a membrane-bound nucleus; includes Bacteria and Archaea; has a nucleoid and limited organelles.

Cytoplasmic membrane

A thin lipid–protein bilayer surrounding the cytoplasm that controls material flow into and out of the cell.

Outer membrane

An extra membrane in Gram-negative bacteria containing lipopolysaccharide; regulates material flow and can release toxic components.

Cell wall

A semirigid layer providing structural support and shape to the cell.

Peptidoglycan

A sugar–amino acid mesh in bacterial cell walls; thicker in Gram-positive cells.

Lipopolysaccharide (LPS)

A component of the outer membrane in Gram-negative bacteria; can act as an endotoxin.

Teichoic acid

Anionic polymers in Gram-positive cell walls that help maintain structure.

Lipoteichoic acid

Teichoic acids anchored to the cytoplasmic membrane in Gram-positive bacteria.

Porin proteins

Channel proteins in the outer membrane that allow small molecules to pass through.

Gram-positive cell envelope

Thick peptidoglycan layer with teichoic/lipoteichoic acids; no outer membrane.

Gram-negative cell envelope

Outer membrane with LPS, thin peptidoglycan, and periplasmic space.

Glycocalyx

A protective, adhesive external layer made of oils, sugars, and proteins; includes capsule and slime layer.

Capsule

Tight external layer that protects and aids adhesion; often visible as a distinct coating.

Slime layer

Diffuse, loosely attached glycocalyx that helps with attachment and protection.

S layer

Protective monolayer of protein surrounding the cell.

Fimbriae

Numerous short appendages used for attachment to surfaces or host cells (Velcro-like).

Pilus

Longer appendage used for DNA transfer (conjugation); typically in Gram-negative bacteria.

Flagellum

A long, rotating filament that provides motility; powered by a basal body.

Axial filaments

Periplasmic flagella found in spirochetes; enable axial movement of the cell.

Periplasmic space

Space between the cytoplasmic and outer membranes in Gram-negative bacteria.

Endospore

A dormant, highly resistant body formed by some bacteria for survival in adverse conditions.

Sporulation

The process of endospore formation.

Germination

Return of a spore to a vegetative, metabolically active cell.

Nucleoid

Region containing the bacterial chromosome; not membrane-bound.

Plasmid

Small, circular DNA carrying extra genes; can be transferred between bacteria.

Ribosome 70S

Prokaryotic ribosome composed of 30S and 50S subunits; target of many antibiotics.

Inclusions/Granules

Stored nutrients (e.g., fat, phosphate, glycogen) that can be tapped when needed.

Bacterial microcompartments

Protein-coated compartments that localize enzymes in the cytoplasm.

Intracellular membranes

Membrane-bound membranes within the cytoplasm (not present in all bacteria).

Cytoplasm

Water-based solution filling the cell; site of biochemical reactions.

Cytoplasmic matrix

Fluid inside the cytoplasm containing water for reactions.

Actin cytoskeleton

Long protein filaments inside the cell that help maintain shape.

Morphology: Coccus

Spherical bacteria, typically 1–2 μm in diameter.

Morphology: Bacillus (bacilli)

Rod-shaped bacteria, typically 2–20 μm long.

Morphology: Spirillum

Spiral-shaped bacteria, often 10–200 μm long.

Diplococci

Pairs of cocci formed by division in one plane.

Streptococci

Chains of cocci formed by division in one plane.

Tetrad

Cocci arranged in a packets of four due to two-plane division.

Sarcina

Cocci arranged in packets of 8–64 cells.

Staphylococci

Irregular grape-like clusters of cocci.

Micrococci

Small irregular clusters of cocci.

Palisades

Rows of cells aligned parallel or in a V-shaped arrangement after division.

Flagellar arrangements

Monotrichous: single flagellum; Peritrichous: flagella all around; Lophotrichous: tufts at ends; Amphitrichous: flagella at both ends.

Run and tumble

Run: movement in one direction; tumble: reorientation after rotation; governs chemotaxis.

Chemotaxis

Movement toward favorable chemicals (nutrients) or away from repellents.

Domains

Three major cellular domains: Bacteria, Archaea (prokaryotes), and Eukarya.

Bergey’s Manual

Reference work for bacterial classification based on phenotypic traits.

Acid-fast cells

Cells with mycolic acids in their walls; associated with pathogenicity.

Mycoplasma

Bacteria lacking a cell wall; highly pleomorphic.