The Bacterial Cell – Vocabulary Review

Vocabulary flashcards cover bacterial cell structure, genetics, physiology, and pathogenicity, helping students master key terms for exam preparation.

Cell Theory

States that all living things are composed of cells and all cells arise from pre-existing cells.

Prokaryotic Cell

Cell lacking a nucleus and membrane-bound organelles; includes bacteria and archaea.

Eukaryotic Cell

Cell containing a true nucleus and membrane-bound organelles; makes up plants, animals, fungi, and protists.

Bacterial Chromosome

Single, circular DNA molecule that contains most of a bacterium’s genetic information.

Nucleoid

Non-membrane-bound region in a prokaryote where the chromosome is aggregated.

Plasmid

Small circular DNA molecule in bacteria carrying non-essential but often advantageous genes such as antibiotic resistance.

Genetic Recombination

Process that rearranges genetic material to create new gene combinations (e.g., transformation, conjugation, transduction in bacteria).

Vertical Gene Transfer

Inheritance of DNA during binary fission; parent and daughter cells are genetically identical.

Horizontal Gene Transfer

Movement of genes between different cells; responsible for genetic diversity in bacteria.

Transformation

Uptake of free DNA from the environment by a competent bacterial cell.

Conjugation

Direct transfer of plasmid DNA between bacteria through a pilus.

Transduction

Transfer of bacterial DNA from one cell to another via bacteriophage (virus).

Pilus (plural pili)

Rigid tubular appendage that mediates conjugation and DNA transfer.

Fimbriae

Short, bristle-like protein appendages used for adhesion to surfaces or other cells.

Flagellum

Long, rotating filament that propels prokaryotic cells by spinning like a propeller.

Antibiotic Resistance Gene

Gene that allows bacteria to survive exposure to specific antibiotics; often located on plasmids.

Virulence Gene

Gene that increases a microorganism’s ability to cause disease (e.g., toxin genes).

Coccus (plural cocci)

Spherical bacterial cell shape.

Bacillus (plural bacilli)

Rod-shaped bacterial cell.

Spirillum (plural spirilla)

Rigid, spiral-shaped bacterium often possessing flagella.

Coccobacillus

Short, oval rod intermediate between coccus and bacillus.

Vibrio

Comma-shaped, slightly curved rod bacterium.

Spirochete

Flexible, corkscrew-shaped bacterium with internal flagella.

Cell Envelope

Protective structure surrounding bacteria; may include glycocalyx, cell wall, and cell membrane.

Glycocalyx

Viscous, polysaccharide/protein outer coating; includes slime layers and capsules.

Slime Layer

Loosely attached, unorganized glycocalyx easily washed off the cell wall.

Capsule

Dense, well-organized glycocalyx firmly attached to the cell wall; resists phagocytosis.

Biofilm

Community of microorganisms attached to a surface, embedded in a self-produced matrix.

Peptidoglycan

Mesh-like polymer of sugars and amino acids forming bacterial cell walls.

Cell Wall

Semi-rigid structure of peptidoglycan that maintains shape and prevents osmotic lysis.

Gram-Positive Bacterium

Bacterium with thick peptidoglycan cell wall, teichoic acids, and purple Gram stain.

Gram-Negative Bacterium

Bacterium with thin peptidoglycan layer, outer membrane with porins, and pink Gram stain.

Teichoic Acids

Polymer in Gram-positive cell walls that reinforces structure and aids adherence.

Porins

Protein channels in Gram-negative outer membranes allowing passage of specific molecules.

Periplasmic Space

Region between inner and outer membranes of Gram-negative bacteria containing enzymes and peptidoglycan.

Cytoplasm

Gelatinous solution (70-80 % water) of sugars, amino acids, and salts where cellular metabolism occurs.

Prokaryotic Ribosome

70S ribosome composed of 30S and 50S subunits that performs protein synthesis.

Inclusion Body

Non-membrane storage granule within bacterial cytoplasm (e.g., glycogen, gas vesicles).

Thylakoid (in bacteria)

Membrane fold containing chlorophyll in cyanobacteria for photosynthesis.

Endospore

Dormant, extremely resistant cell structure formed by certain bacteria under stress.

Sporulation

Process of endospore formation when conditions become unfavorable.

Germination

Return of an endospore to the vegetative, replicative state when conditions improve.

Chemotaxis

Movement of bacteria toward or away from chemical stimuli.

Phototaxis

Movement of bacteria in response to light.

Thermotaxis

Movement of bacteria in response to temperature changes.

Run (flagellar)

Straight, counterclockwise flagellar rotation producing forward movement.

Tumble (flagellar)

Brief clockwise flagellar rotation causing the cell to reorient.

Basal Body

Motor complex of rings and a rod anchoring the flagellum to the cell envelope.

Filament (flagellar)

Long, helical, protein extension of a flagellum responsible for propulsion.

R Factor

Plasmid carrying genes that confer multiple antibiotic resistances.

Crossing Over

Eukaryotic meiotic recombination event exchanging genetic material between homologous chromosomes.

Anthrax

Disease caused by Bacillus anthracis, a spore-forming bacterium.

Tetanus

Neuroparalytic disease caused by Clostridium tetani spores.

Botulism

Foodborne illness caused by neurotoxin-producing Clostridium botulinum spores.