Prokaryotic Cell Structure, Growth, Pathogenicity, and Genetics

Comprehensive vocabulary flashcards covering bacterial cell wall structures, Gram staining, plasma membrane transport, physical and chemical growth requirements, biofilms, binary fission, mechanisms of pathogenicity, bacterial toxins, and gene transfer mechanisms.

Wall Teichoic Acid

An acid attached to peptidoglycan in Gram-positive cell walls that provides structure, strengthens and stabilizes the cell wall, and creates an overall negative charge.

Lipoteichoic Acid

An acid attached to the lipid bilayer in Gram-positive cell walls that stands straight up through the peptidoglycan layer to assist with adhesion and host cell interactions.

Gram-Positive Cell Wall

A bacterial cell wall characteristically composed of a thick peptidoglycan layer containing wall teichoic acid and lipoteichoic acid, lacking an outer membrane.

Lipopolysaccharide (LPS)

A major component of the outer membrane of Gram-negative bacteria, consisting of Lipid A, core polysaccharide, and O polysaccharide.

Lipid A

The lipid component embedded inside the outer membrane layer of Gram-negative bacteria that acts as an endotoxin released when cells divide, die, or digest.

Core Polysaccharide

The structural portion of lipopolysaccharide (LPS) that connects Lipid A to the O antigen.

O Polysaccharide (O Antigen)

The outermost portion of lipopolysaccharide (LPS) that sticks out from the surface of Gram-negative bacteria and helps them invade host tissues.

Periplasm

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

Porin Protein

A channel protein located inside the outer membrane of Gram-negative bacteria that allows small molecules to pass through.

Lipoprotein (Gram-Negative)

A protein located in the space between the plasma membrane bilayer and outer membrane that stabilizes the outer membrane by anchoring it to peptidoglycan.

Gram-Negative Cell Wall

A complex bacterial cell wall featuring a thin peptidoglycan layer within the periplasm, surrounded by an outer phospholipid membrane containing LPS and porins.

Orthopoxvirus Diameter

A viral diameter measurement defined as $0.3\,\mu\text{m}$.

Staphylococcus Diameter

A single-celled bacterial diameter measurement defined as $1\,\mu\text{m}$.

Giardia Length

A single-celled parasitic protozoan length measurement defined as $14\,\mu\text{m}$.

Chicken Egg Diameter

A macroscopic structure diameter measurement defined as $4.7\,\text{cm}$ ($47,000\,\mu\text{m}$).

Eukaryotic Ribosome

The protein synthesis machinery found in eukaryotic cells, designated as an $80\text{S}$ ribosome.

Prokaryotic Ribosome

The protein synthesis machinery found in all bacteria, designated as a $70\text{S}$ ribosome.

Capsule

An organized unit of glycocalyx composed of sticky polysaccharides or polypeptides that is firmly attached to the bacterial cell surface.

Slime Layer

A loose, water-soluble glycocalyx structure outside the cell wall that aids in attachment and protection.

Glycocalyx

A gelatinous, sticky substance surrounding the outside of a cell made of polysaccharides or polypeptides that contributes to virulence.

Flagella

Long filamentous appendages that project from the bacterial surface and rotate to provide motility.

Filament (Flagella)

The long, outermost region of a flagellum that extends into the surrounding medium.

Hook (Flagella)

The curved tubular structure attached to the filament that links it to the basal body.

Basal Body

The motor structure of a flagellum that anchors the flagellar assembly into the bacterial cell wall and plasma membrane.

Axial Filament (Endoflagella)

Bundles of fibrils that arise at the ends of spirochetes and spiral around the cell in the periplasmic space to enable corkscrew movement.

Phototaxis

Bacterial movement in directional response to a light stimulus.

Chemotaxis

Bacterial movement in directional response to a chemical stimulus.

Fimbriae

Hair-like appendages found on the ends or surface of bacteria, ranging from a few to several hundred per cell, used for adhering to surfaces.

Pili (Pilus)

Appendages longer than fimbriae, typically present at one or two per cell, responsible for bacterial motility and DNA transfer.

Neisseria gonorrhoeae Attachment Site

A pathogenic bacterium that utilizes fimbriae to adhere specifically to host mucous membranes.

E. coli O157 Attachment Site

A pathogenic bacterial strain that utilizes fimbriae to attach to the lining of the host small intestine.

Coccus

A spherical or circular bacterial cell morphology.

Bacillus

A long, straight rod-shaped bacterial cell morphology.

Vibrio

A curved rod or boomerang-shaped bacterial cell morphology.

Spirillum

A rigid, squiggly or helical bacterial cell morphology.

Spirochete

A flexible, spiral-shaped bacterial cell morphology.

Coccobacillus

A bacterial shape intermediate between a coccus and a bacillus.

Monomorphic

Bacteria that maintain a single, constant cell shape.

Pleomorphic

Bacteria that naturally display many different or unusual shapes.

Diplococci

Cocci that remain living together in pairs after division.

Streptococci

Cocci that remain attached to form long chain-like arrangements.

Staphylococci

Cocci that divide in multiple planes to form cluster-like arrangements.

Tetrad

A group of four cocci arranged stacked together in two planes.

Sarcinae

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

Streptobacilli

Bacilli that remain attached in long chain arrangements.

Diplobacilli

Pairs of bacilli that remain attached end-to-end after cell division.

Peptidoglycan

A macromolecule composed of repeating disaccharide units attached by short polypeptide bridges that forms bacterial cell walls.

N-acetylglucosamine (NAG)

One of the two alternating sugar monosaccharide units that build the peptidoglycan disaccharide backbone.

N-acetylmuramic Acid (NAM)

The sugar monosaccharide unit in peptidoglycan to which amino acid side chains are attached.

Peptide Cross-Bridge

A short chain of amino acids linking adjacent NAM-NAG glycan strands in peptidoglycan.

Exotoxin

A toxic protein produced inside and secreted out of living bacterial cells into surrounding medium.

Endotoxin

The Lipid A portion of lipopolysaccharide within the Gram-negative outer cell wall that is released when the cell dies or disintegrates.

Crystal Violet

The primary purple dye applied first in the Gram stain procedure that penetrates both Gram-positive and Gram-negative cell walls.

Iodine (Gram Stain)

The mordant in Gram staining that forms a large complex with crystal violet inside the cell wall.

Alcohol Wash (Decolorizer)

The ethanol step in Gram staining that dehydrates Gram-positive peptidoglycan while dissolving Gram-negative outer membranes.

Safranin

The red counterstain applied in Gram staining that colors decolorized Gram-negative cells.

Gram-Positive Stain Color

The purple color retained by Gram-positive cells because their thick peptidoglycan retains the crystal violet-iodine complex.

Gram-Negative Stain Color

The red or pink color assumed by Gram-negative cells after accepting safranin counterstain.

Cyanobacteria Gram Reaction

An example organism that stains Gram-positive purple.

Salmonella Gram Reaction

An example bacterial genus that stains Gram-negative red.

Cytoplasmic Membrane (Plasma Membrane)

A selectively permeable phospholipid bilayer surrounding the bacterial cytoplasm, regulating nutrient entry, waste exit, and energy production.

Polymyxins

A class of last-resort antibiotics that target and disrupt bacterial plasma membranes.

Hydrophilic Polar Head

The water-attracting phosphate group and glycerol region facing outward in a plasma membrane lipid bilayer.

Hydrophobic Nonpolar Tail

The water-repelling fatty acid chain region positioned inward in a plasma membrane lipid bilayer.

Peripheral Proteins

Proteins loosely attached on the inner or outer surface of the plasma membrane bilayer.

Integral Proteins

Proteins inserted directly into or spanning across the lipid bilayer of the plasma membrane.

Simple Diffusion

Passive net movement of solutes down a concentration gradient across the membrane without energy or transporter proteins.

Facilitated Diffusion

Passive transport of substances across a biological membrane mediated through specific channel or carrier proteins without ATP.

Osmosis

The net diffusion of water across a selectively permeable membrane from higher to lower water concentration.

Isotonic Solution

A medium where solute concentration equals that inside the cell, causing no net water movement.

Hypertonic Solution

A solution with higher solute concentration than inside the cell, causing water exit and cell shrinking.

Hypotonic Solution

A solution with lower solute concentration than inside the cell, causing water entry into the cell.

Plasmolysis

Shrinkage of a bacterial cell membrane away from its cell wall when placed in a hypertonic environment.

Uniport

An active transport carrier mechanism moving a single chemical substance across a membrane in one direction.

Antiport

An active transport mechanism moving two substances simultaneously in opposite directions across the membrane.

Symport

A coupled active transport mechanism moving two substances in the same direction across the membrane.

Group Translocation

An active transport mechanism exclusive to bacteria wherein a substance is chemically altered during transport so it cannot escape.

Glucose-6-Phosphate

The phosphorylated form of glucose trapped inside bacterial cytoplasm following group translocation using a phosphate group ($\text{PO}_4$).

Cytosol

The liquid fluid portion of the cytoplasm inside a bacterial cell.

Nucleoid

The region in prokaryotic cytoplasm containing the single, long, circular, double-stranded DNA bacterial chromosome.

Inclusions

Reserve deposit granules in bacterial cytoplasm used to store nutrients and chemical compounds.

70S Ribosome Subunits

The prokaryotic ribosomal complex consisting of small and large subunits targeted specifically by antibacterial drugs.

Endospores

Extremely resistant resting structures formed by certain bacteria under nutrient limitation to protect genetic material.

Bacillus and Clostridioides

The primary bacterial genera famous for producing endospores.

Spore Coat

A tough protective protein coating that renders endospores resistant to heat, drying, radiation, and lethal chemicals.

Germination

The process where an endospore returns to a vegetative growth state when environmental conditions improve.

Minimum Growth Temperature

The lowest temperature at which a microbial species can conduct metabolic activity and grow.

Maximum Growth Temperature

The highest temperature at which microbial growth is possible before protein denaturation occurs.

Optimum Growth Temperature

The specific temperature that produces the highest growth rate and metabolic activity for an organism.

Psychrophiles

Cold-loving microbes capable of growing between $0^\circ\text{C} - 20^\circ\text{C}$, sensitive to higher temperatures.

Psychrotrophs

Cold-tolerant organisms growing between $0^\circ\text{C} - 30^\circ\text{C}$ that cause food spoilage inside refrigerators.

Mesophiles

Microbes with growth optima between $25^\circ\text{C} - 40^\circ\text{C}$, including most human pathogens that thrive near average body temperature ($37^\circ\text{C}$).

Thermophiles

Heat-loving microbes growing best in elevated temperature ranges between $50^\circ\text{C} - 60^\circ\text{C}$.

Hyperthermophiles

Extreme thermophiles living in hot springs with optimal growth temperatures of $80^\circ\text{C}$ or higher.

Bacillus cereus in Rice

A foodborne pathogen that multiplies within rice at temperatures between $15^\circ\text{C} - 43^\circ\text{C}$.

Acidophiles

Organisms such as fungi and specialized bacteria that grow optimally in acidic environments with $\text{pH} < 7$.

Neutrophiles

Bacteria (including most pathogens) that grow best in narrow neutral pH ranges between $\text{pH } 6.5 - 7.5$.

Alkalinophiles

Soil and water microbes adapted to live in alkaline environments ranging from $\text{pH } 8 - 14$.

Obligate Halophiles

Microorganisms that strictly require high salt concentrations in their environment to grow.

Facultative Halophiles

Microorganisms capable of tolerating high salt conditions without strictly requiring them.