Functional Anatomy of Prokaryotic and Eukaryotic Cells

Comprehensive vocabulary flashcards covering key terms, structures, and processes from Chapter 4: Functional Anatomy of Prokaryotic and Eukaryotic Cells.

Prokaryote

Organism whose name comes from Greek words for prenucleus; characteristically has one circular chromosome not enclosed in a membrane, lacks histones and membrane-bound organelles, and divides by binary fission.

Eukaryote

Organism whose name comes from Greek words for true nucleus; characteristically has paired chromosomes enclosed inside a nuclear membrane, contains histones and organelles, and divides by mitosis.

Monomorphic

Describing bacteria that maintain a single, constant shape throughout their life cycle.

Pleomorphic

Describing bacteria that can naturally exist in multiple or variable shapes.

Coccus

A spherical or round bacterial cell shape.

Diplococci

Cocci that remain in pairs after dividing in a single plane.

Streptococci

Cocci that remain attached in chainlike patterns after dividing in a single plane.

Tetrad

A group of four cocci resulting from cell division in two planes.

Sarcinae

A cubelike packet of eight cocci resulting from cell division in three regular planes.

Staphylococci

Cocci arranged in grape-like clusters or broad sheets resulting from division in multiple random planes.

Bacillus

A rod-shaped bacterial cell shape; also refers to a specific scientific genus of bacteria.

Diplobacilli

Bacilli that remain in pairs after cell division.

Streptobacilli

Bacilli that occur attached end-to-end in long chains.

Coccobacillus

A bacterium with a short, oval shape intermediate between a coccus and a bacillus.

Vibrio

A curved, rod-shaped spiral bacterial cell.

Spirillum

A helical, rigid spiral bacterium with external flagella.

Spirochete

A helical, flexible spiral bacterium that moves via internal axial filaments.

Glycocalyx

A viscous, gelatinous polymer composed of polysaccharide, polypeptide, or both, secreted external to the bacterial cell wall.

Capsule

An organized glycocalyx structure firmly attached to the cell wall that contributes to bacterial virulence by preventing phagocytosis.

Slime layer

An unorganized glycocalyx that is loosely attached to the cell wall.

Extracellular polymeric substance (EPS)

A component of glycocalyx that enables microorganisms to attach to surfaces and form biofilms.

Flagella

Long filamentous appendages external to the cell wall that rotate to propel bacteria.

Flagellin

The globular protein that forms the helical filament of bacterial flagella.

Peritrichous

Flagella arrangement distributed across the entire surface of the bacterial cell.

Monotrichous

Flagella arrangement consisting of a single flagellum located at one pole of the cell.

Lophotrichous

Flagella arrangement consisting of a tuft of flagella originating from one pole of the cell.

Amphitrichous

Flagella arrangement with flagella located at both poles of the cell.

Taxis

The movement of a bacterium toward or away from a specific environmental stimulus.

H antigens

Flagellar proteins useful for distinguishing and identifying specific serovars of Gram-negative bacteria.

Axial filaments

Also called endoflagella; bundles of fibrils anchored at one end of spirochetes that wrap around the cell and rotate to generate corkscrew movement.

Fimbriae

Hairlike appendages found in bacteria that facilitate attachment to surfaces and host tissues.

Pili

Bacterial surface appendages involved in twitching/gliding motility and the transfer of DNA between cells during conjugation.

Peptidoglycan

A macromolecular polymer in bacterial cell walls consisting of repeating disaccharides (NAG and NAM) cross-linked by short polypeptide chains.

N-acetylglucosamine (NAG)

One of the two alternating monosaccharide derivatives that form the carbohydrate backbone of peptidoglycan.

N-acetylmuramic acid (NAM)

One of the two alternating monosaccharide derivatives in peptidoglycan to which amino acid side chains attach.

Teichoic acids

Acidic alcohol-phosphate polymers present in Gram-positive cell walls that bind and regulate cation movement and provide antigenic specificity.

Lipoteichoic acid

A teichoic acid in Gram-positive bacterial cell walls that spans the peptidoglycan layer and links it to the plasma membrane.

Wall teichoic acid

A teichoic acid linked exclusively to the peptidoglycan layer of Gram-positive cell walls.

Periplasm

The fluid-filled space between the outer membrane and plasma membrane in Gram-negative bacteria containing peptidoglycan and digestive enzymes.

Lipopolysaccharide (LPS)

A complex molecule located in the outer membrane of Gram-negative bacteria composed of Lipid A, core polysaccharide, and O polysaccharide.

O polysaccharide

The carbohydrate antigen component of LPS extending outward from the outer membrane, useful for distinguishing bacterial serovars.

Lipid A

The toxic lipid component of lipopolysaccharide embedded in the outer membrane of Gram-negative bacteria that acts as an endotoxin.

Porins

Transmembrane proteins in the outer membrane of Gram-negative bacteria that form water-filled channels allowing small molecules to pass.

Lysozyme

A digestive enzyme that breaks cell walls by hydrolyzing glycosidic bonds between NAG and NAM in peptidoglycan.

Protoplast

A wall-less Gram-positive bacterial cell resulting from complete peptidoglycan destruction, surrounded only by a plasma membrane.

Spheroplast

A spherical, wall-damaged Gram-negative cell retaining part of its outer membrane following peptidoglycan degradation.

L forms

Mutant or cell wall-deficient bacterial strains that lose their characteristic shape and swell into irregular forms.

Fluid mosaic model

A structural model of the plasma membrane describing dynamic protein movement within a flexible phospholipid bilayer.

Chromatophores

Infoldings of the plasma membrane containing photosynthetic pigments and enzymes found in photosynthetic bacteria.

Simple diffusion

Passive net movement of solutes from an area of higher concentration to lower concentration until dynamic equilibrium is reached.

Facilitated diffusion

Passive transport of ions or large molecules across a membrane through transporter proteins along a concentration gradient.

Osmosis

The net movement of solvent water molecules across a selectively permeable membrane from an area of high water concentration to low water concentration.

Aquaporins

Transmembrane protein channels that specifically facilitate the passage of water molecules across cell membranes.

Osmotic pressure

The force required to prevent the movement of pure water into a solution containing solutes across a selectively permeable membrane.

Isotonic solution

A medium in which the concentration of solutes equals that inside the cell, resulting in no net movement of water.

Hypotonic solution

A medium with a lower solute concentration than inside the cell, causing water to enter and potentially burst the cell (osmotic lysis).

Hypertonic solution

A medium with a higher solute concentration than inside the cell, causing water to move out and cytoplasm to shrink (plasmolysis).

Active transport

The energy-requiring transport of substances across a membrane against a concentration gradient using ATP and carrier proteins.

Group translocation

A specialized active transport mechanism in prokaryotes where a substance is chemically modified (using phosphoenolpyruvic acid, PEP) as it crosses the plasma membrane.

Nucleoid

The nuclear region in a prokaryotic cell containing the single circular bacterial chromosome carrying genetic information.

Plasmids

Small, circular, extrachromosomal DNA elements that carry non-essential genes such as antibiotic resistance and toxin production.

70S Ribosomes

Prokaryotic protein synthesis complexes composed of a 50S large subunit and a 30S small subunit.

Metachromatic granules

Also called volutin; cytoplasmic inclusions that store inorganic phosphate reserves used for ATP synthesis.

Carboxysomes

Inclusions containing the enzyme ribulose 1,5-bisphosphate carboxylase (RuBisCO) required for carbon dioxide fixation during photosynthesis.

Magnetosomes

Intracellular inclusions of iron oxide that assist bacteria in orienting along magnetic fields and destroying toxic $H_2O_2$.

Endospores

Specialized, highly durable, dormant resting cells produced by Bacillus and Clostridium to withstand heat, chemicals, desiccation, and radiation.

Sporulation

The multi-step process of endospore formation within a vegetative cell triggered by nutrient depletion.

Germination

The process by which a dormant endospore returns to an actively growing vegetative state.

Endocytosis

An active transport mechanism in eukaryotic cells in which the plasma membrane engulfs extracellular materials via phagocytosis or pinocytosis.

Phagocytosis

A form of endocytosis where cellular extensions called pseudopods engulf solid particles or microbes.

Pinocytosis

A form of endocytosis where the plasma membrane folds inward to bring in extracellular fluid and dissolved solutes.

Cytoplasmic streaming

The continuous movement of eukaryotic cytoplasm throughout the cell to distribute nutrients and intracellular structures.

80S Ribosomes

Eukaryotic ribosomes consisting of a 60S large subunit and a 40S small subunit, located free in the cytoplasm or bound to the endoplasmic reticulum.

Rough endoplasmic reticulum

Membranous organelle continuous with the nuclear envelope studded with ribosomes, serving as a primary site of protein synthesis.

Smooth endoplasmic reticulum

Membranous network lacking ribosomes that synthesizes cell membranes, fats, and steroid hormones.

Golgi complex

An organelle consisting of flattened cisternae that modifies, sorts, and packages ER proteins into transport vesicles.

Lysosomes

Membrane-enclosed vesicles formed by the Golgi complex containing powerful digestive enzymes.

Chloroplasts

Photosynthetic organelles in plant and algal cells containing thylakoid membranes packed with chlorophyll.

Peroxisomes

Organelles containing oxidative enzymes that breakdown fatty acids and destroy toxic hydrogen peroxide ($H_2O_2$).

Centrosomes

Structures composed of pericentriolar material and centrioles that organize microtubules and form the mitotic spindle during cell division.

Endosymbiotic theory

The evolutionary theory asserting that eukaryotic cells arose when larger host cells engulfed symbiotic photosynthetic and aerobic bacteria, which became chloroplasts and mitochondria.