Functional Anatomy of Prokaryotic and Eukaryotic Cells – Key Vocabulary

Vocabulary flashcards summarizing essential terms and definitions from Chapter 4, covering prokaryotic and eukaryotic cell structure, functions, and evolutionary concepts.

Prokaryote

Cell type lacking a true nucleus; DNA is not enclosed by a membrane and usually occurs as one circular chromosome.

Eukaryote

Cell type with DNA housed in a true nucleus and usually containing membrane-bound organelles.

Monomorphic

Describes bacteria that maintain a single cellular shape.

Pleomorphic

Describes bacteria capable of assuming multiple shapes.

Bacillus (shape)

Rod-shaped bacterial cell (lowercase, non-italicized).

Bacillus (genus)

Capitalized and italicized term for the genus that includes B. anthracis.

Coccus

Spherical-shaped bacterium.

Vibrio

Curved-rod (comma-shaped) spiral bacterium.

Spirillum

Rigid helical bacterium with external flagella.

Spirochete

Flexible helical bacterium propelled by axial filaments.

Diplococci

Pair of cocci resulting from one plane of division.

Streptococci

Chain of cocci formed by repeated divisions in one plane.

Staphylococci

Irregular cluster of cocci produced by multiple planes of division.

Tetrad

Group of four cocci produced by division in two planes.

Sarcinae

Cubelike packet of eight cocci produced by division in three planes.

Glycocalyx

Viscous polysaccharide and/or polypeptide coating external to bacterial cell wall.

Capsule

Neatly organized, firmly attached glycocalyx that resists phagocytosis and aids virulence.

Slime Layer

Unorganized, loosely attached glycocalyx involved in surface adherence and biofilm formation.

Biofilm

Community of microbes attached to a surface, embedded in extracellular polymeric substance.

Flagellum

Long, filamentous appendage that propels bacteria; composed of flagellin filament, hook, and basal body.

Peritrichous Flagella

Flagella distributed over the entire bacterial surface.

Monotrichous Flagellum

Single flagellum located at one pole.

Lophotrichous Flagella

Tuft of flagella emerging from one pole.

Amphitrichous Flagella

Flagella located at both poles of the cell.

Run (Swim)

Straight, smooth bacterial movement powered by flagellar rotation in one direction.

Tumble

Abrupt, random change in direction caused by reversal of flagellar rotation.

Taxis

Directed movement toward or away from a stimulus (chemotaxis, phototaxis).

H Antigen

Flagellar protein used to differentiate bacterial serovars (e.g., E. coli O157:H7).

Archaella

Rotating motility structures of archaea composed of archaellins.

Axial Filament

Endoflagellum wrapped around spirochetes, producing corkscrew motility.

Fimbriae

Numerous, short, hairlike appendages that mediate attachment and biofilm formation.

Pilus

Longer appendage; involved in twitching or gliding motility and DNA transfer (conjugation pili).

Conjugation Pilus

Specialized pilus that transfers DNA between bacterial cells.

Cell Wall (Bacteria)

Rigid structure preventing osmotic lysis; composed mainly of peptidoglycan.

Peptidoglycan (Murein)

Polymer of alternating N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) linked by peptide cross-bridges.

N-acetylglucosamine (NAG)

One of the alternating sugars in the peptidoglycan backbone.

N-acetylmuramic Acid (NAM)

Peptidoglycan sugar that bears tetrapeptide side chains for cross-linking.

Tetrapeptide Side Chain

Four-amino-acid chain attached to NAM, linking rows of peptidoglycan.

Gram-Positive Cell Wall

Thick peptidoglycan layer with teichoic acids; stains purple in Gram stain.

Teichoic Acid

Polyalcohol embedded in gram-positive walls; binds cations and confers antigenic specificity.

Lipoteichoic Acid

Teichoic acid subtype linking peptidoglycan to plasma membrane lipids.

Gram-Negative Cell Wall

Thin peptidoglycan plus outer membrane containing lipopolysaccharide; stains pink/red.

Outer Membrane

Gram-negative membrane of phospholipids, lipoproteins, and LPS; barrier to detergents and antibiotics.

Lipopolysaccharide (LPS)

Outer-membrane component with lipid A, core polysaccharide, and O polysaccharide antigen.

Lipid A

Endotoxic component of LPS responsible for fever and shock when released.

O Polysaccharide

Outer part of LPS functioning as antigenic determinant of gram-negative bacteria.

Porin

Protein channel in gram-negative outer membrane allowing passage of small molecules.

Gram Stain Mechanism

Differential stain where crystal violet-iodine complex is retained by thick peptidoglycan but lost from thin walls after alcohol treatment.

Acid-Fast Cell Wall

Peptidoglycan plus waxy mycolic acid; resists Gram stain and dyes; characteristic of Mycobacterium and Nocardia.

Mycolic Acid

Long-chain waxy lipid responsible for acid-fastness.

Mycoplasma

Bacteria lacking cell walls; plasma membrane contains sterols for rigidity.

Pseudomurein

Peptidoglycan-like cell wall component of certain archaea lacking NAM and D-amino acids.

Lysozyme

Enzyme in tears and saliva that hydrolyzes β-1,4 linkages in peptidoglycan.

Penicillin

Antibiotic that inhibits peptide cross-bridge formation in peptidoglycan.

Protoplast

Wall-less gram-positive cell produced by lysozyme or penicillin action.

Spheroplast

Wall-less gram-negative cell that retains outer membrane.

L Form

Bacterial variant that has lost its cell wall and can grow/replicate without it.

Plasma (Cytoplasmic) Membrane

Phospholipid bilayer with proteins; site of selective permeability, ATP production, and transport.

Fluid Mosaic Model

Describes membrane as viscous, self-sealing bilayer with lateral movement of lipids and proteins.

Simple Diffusion

Passive movement of solute across membrane down its concentration gradient.

Facilitated Diffusion

Passive transport aided by membrane transporter proteins; down gradient.

Osmosis

Passive movement of water across selectively permeable membrane toward lower water concentration.

Aquaporin

Protein channel that accelerates water transport across membranes.

Active Transport

Energy-requiring movement of substances against concentration gradient using transporter proteins and ATP.

Group Translocation

Prokaryotic active transport in which substance is chemically modified (e.g., glucose → glucose-6-P) during uptake via PEP energy.

Cytoskeleton (Prokaryotic)

Network of MreB, ParM, crescentin, and FtsZ proteins giving shape and aiding cell division.

Nucleoid

Region containing the single circular bacterial chromosome.

Plasmid

Small, circular, extrachromosomal DNA carrying non-essential genes such as antibiotic resistance.

70S Ribosome

Prokaryotic ribosome composed of 50S and 30S subunits; site of protein synthesis.

Inclusion

Intracellular reserve deposit (e.g., metachromatic granules, lipid inclusions, gas vacuoles).

Metachromatic Granule (Volutin)

Cytoplasmic inclusion storing inorganic phosphate.

Carboxysome

Inclusion containing ribulose-1,5-bisphosphate carboxylase for CO₂ fixation.

Gas Vacuole

Protein-bound cavity providing buoyancy in aquatic prokaryotes.

Magnetosome

Iron oxide inclusion enabling orientation to magnetic fields and decomposition of H₂O₂.

Endospore

Highly resistant, dormant cell formed by Bacillus and Clostridium when nutrients are scarce.

Sporulation

Process of endospore formation inside vegetative cell.

Germination

Return of an endospore to the vegetative state upon favorable conditions.

80S Ribosome

Eukaryotic ribosome composed of 60S and 40S subunits; may be free or membrane-bound.

9 + 2 Arrangement

Microtubule structure of eukaryotic flagella/cilia: nine doublets surrounding two central microtubules.

Pellicle

Flexible outer protein covering of many protozoa replacing a rigid wall.

Endocytosis

Eukaryotic uptake of materials via plasma-membrane invagination.

Phagocytosis

Type of endocytosis where pseudopods engulf large particles or microbes.

Pinocytosis

Endocytic process that brings extracellular fluid and dissolved solutes into the cell.

Endosymbiotic Theory

Hypothesis that mitochondria and chloroplasts originated from engulfed prokaryotes living symbiotically within ancestral eukaryotes.