Elements of Microbiology - Introduction, Classification, and Biological Chemistry

Comprehensive practice flashcards defining foundational concepts in microbiology, historic experiments, taxonomy, microbial groups, helminth parasites, and biological chemistry.

Spontaneous Generation (Abiogenesis)

An obsolete theory stating that living organisms can originate directly from inanimate matter, such as mice arising from bread or flies from decaying meat.

Redi's Experiment

A 1668 investigation using open, tightly sealed, and cloth-covered jars containing meat to demonstrate that macroscopic organisms such as flies do not generate spontaneously.

Pasteur's Swan-Neck Flask Experiment

An 1861 demonstration that microorganisms are present in the air; broth boiled in an intact curved flask remained sterile, while breaking the neck permitted germ-laden air to induce microbial growth.

Law of Biogenesis

The biological principle expressed as Omne vivum ex vivo, asserting that all living matter originates exclusively from preexisting life.

Anton van Leeuwenhoek

Known as the "father of microscopy"; he ground over 500 optical lenses and was the first person to observe bacteria, protists, spermatozoa, blood cells, and muscle fibers.

Edward Jenner

Regarded as the "father of immunology"; in 1796, he inoculated an 8-year-old child with fluid from cowpox blisters, establishing the first vaccination process to protect against smallpox.

Joseph Lister

A British surgeon who pioneered antiseptic surgery in the 1860s by using phenol to disinfect surgical wounds, markedly reducing postoperative infections.

Robert Koch

A physician who definitively proved in 1876 that bacteria cause specific diseases by culturing Bacillus anthracis from infected cattle blood and inoculating it into healthy cattle.

Biofilm

A structured community of microorganisms adhering to a surface that is encased in a protective extracellular matrix, making it difficult for biocides to penetrate effectively.

Quorum Sensing

A chemical signaling mechanism used by bacteria to communicate and coordinate group behaviors and gene expression based on cell density.

Bioremediation

The application of microorganisms to degrade or neutralize toxic, hazardous environmental pollutants into harmless end products.

Communicable Disease

An infectious disease capable of spreading directly or indirectly from one host to another within a population.

Noncommunicable Disease

A disease that is not transmitted or spread from one individual host to another.

Airborne Transmission

A route of vehicle disease transmission involving the spread of microbial agents in dust or droplet nuclei traveling over distances exceeding $1\,m$.

Binomial Nomenclature

The formal naming system established by Carl Linnaeus that assigns each organism a two-part scientific name consisting of a capitalized genus and a lowercase specific epithet.

Peptidoglycan

A macromolecular meshwork composed of repeating carbohydrate polymers cross-linked by short amino acid chains that forms the bacterial cell wall.

Archaea

A domain of unicellular prokaryotes whose cell walls lack peptidoglycan and which typically inhabit extreme or specialized ecological niches.

Methanogens

Archaea that generate methane gas as a byproduct of their metabolic processes, found in anaerobic environments and within the human body.

Extreme Halophiles

Organisms within domain Archaea specialized to inhabit hypersaline environments with extraordinarily high salt concentrations.

Extreme Thermophiles

Archaea adapted to thrive at extremely high environmental temperatures.

Prions

Infectious, misshaped protein particles lacking nucleic acids that cause fatal transmissible spongiform encephalopathies such as mad cow disease and chronic wasting disease (CWD).

Endosymbiosis Theory

The evolutionary theory supported by Lynn Margulis proposing that eukaryotic mitochondria and chloroplasts originated from ancestral endosymbiotic prokaryotic cells.

Bergey's Manual of Determinative Bacteriology

The primary laboratory manual utilized by microbiologists to categorize and identify bacteria based on morphology, staining characteristics, oxygen needs, and biochemical testing.

Rapid Identification Methods

Standardized multi-compartment diagnostic systems (such as the Enterotube II) that perform multiple biochemical colorimetric assays simultaneously for clinically relevant bacteria.

Western Blotting

A laboratory serological technique designed to separate and detect specific proteins; it serves as the principal confirmatory test for identifying Lyme disease infections.

Phage Typing

A diagnostic method that characterizes and differentiates bacterial species or strains based on their susceptibility to lysis by specific bacteriophages.

Dimorphic Fungus

A fungus capable of transitioning between two distinct morphological phases, growing either as a single-celled yeast or as a multicellular filamentous mold (e.g., Candida albicans).

Archaezoa

A group of unicellular flagellated protozoans that lack true mitochondria, possessing primitive mitosomes for energy production instead (e.g., Trichomonas vaginalis).

Ciliophora

A phylum of protozoans that utilize coordinated hair-like cilia for movement and nutrient ingestion, exemplified by Paramecium and the intestinal parasite Balantidium coli.

Amoebozoa

A protozoan group that locomotes via dynamic cytoplasmic projections known as pseudopods; includes Naegleria fowleri, which causes primary amoebic meningoencephalitis.

Apicomplexa

A taxon of obligate intracellular parasitic protozoans equipped with a specialized apical complex designed to penetrate host cells, such as the malaria pathogen Plasmodium vivax.

Dioecious

Describing helminth or animal species that have separate male and female reproductive individuals (such as the pinworm Enterobius vermicularis).

Monoecious

Describing hermaphroditic organisms containing both male and female functional reproductive systems within a single individual (such as Fasciola hepatica).

Trematodes (Flukes)

A class of leaf-shaped parasitic flatworms (platyhelminths) that affix to internal host structures using distinct oral and ventral suckers.

Cestodes (Tapeworms)

Segmented intestinal flatworms consisting of an anterior attachment head (scolex) bearing suckers or hooks, an unsegmented neck, and egg-filled segments called proglottids.

Nematodes (Roundworms)

Cylindrical, unsegmented multicellular parasitic worms that constitute the most abundant multicellular animals on Earth, causing infection via ingested eggs or burrowing larvae.

Valence Shell

The outermost electron shell of an atom involved in forming chemical bonds; contains up to eight electrons when fully saturated and nonreactive.

Ionic Bond

A chemical attraction between oppositely charged ions formed by the full transfer of one or more valence electrons from one atom to another.

Covalent Bond

A strong chemical linkage created when two atoms share one or more pairs of electrons to fill their outer valence shells.

Hydrogen Bond

A weak noncovalent attractive force between a slightly positive hydrogen atom and an electronegative atom, such as oxygen or nitrogen.

Dehydration Reaction

An anabolic, energy-consuming biosynthetic chemical reaction in which smaller reactant molecules combine into a larger compound with the elimination of a water molecule.

Hydrolytic Reaction

A catabolic, energy-releasing degradative reaction that cleaves complex covalent bonds by the chemical addition of water ($H_2O$).

Buffer

A chemical homeostatic agent that resists shifts in $pH$ by accepting or donating hydrogen ions ($H^+$), maintaining physiological levels between $7.4$ and $7.5$.

Tonicity

The relative concentration of solutes in a surrounding extracellular solution compared to intracellular cytoplasm, governing osmotic water movement across the membrane.

Hypertonic Solution

A solution characterized by a higher solute concentration than the cellular interior, driving net osmotic water efflux that leads to cell shrinkage (crenation).

Hypotonic Solution

A solution with a lower solute concentration than the cell interior, causing net osmotic influx of water that makes the cell swell and potentially burst (hemolysis).

Isotonic Solution

A solution possessing the same solute concentration as the cytoplasm of the cell, resulting in no net gain or loss of water.

Saturated Fatty Acid

A lipid tail without double bonds between carbon atoms, allowing hydrocarbon chains to pack tightly together and stay solid at room temperature.

Unsaturated Fatty Acid

A lipid tail possessing one or more carbon-carbon double bonds ($C=C$), introducing kinks that prevent tight molecular packing and keep the substance liquid at room temperature.

Prostaglandins

Short-chain fatty acid molecules that regulate local cellular signaling and pain mediation; their activity is blocked or inhibited by analgesics like aspirin and ibuprofen.

Phospholipid

An amphipathic structural lipid composed of a hydrophilic phosphate head and two hydrophobic fatty acid tails that self-assembles into cellular membrane bilayers.

Peptide Bond

The covalent chemical bond linking the amino group ($-NH_2$) of one amino acid to the carboxyl group ($-COOH$) of an adjacent amino acid in a polypeptide.

Primary Protein Structure

The linear sequence of amino acids joined consecutively through covalent peptide bonds to form a polypeptide chain.

Secondary Protein Structure

Localized, repetitive folding configurations—namely alpha helices and beta pleated sheets—stabilized by hydrogen bonds along the polypeptide backbone.

Tertiary Protein Structure

The complete three-dimensional globular or fibrous conformational shape formed by complex interactions among the amino acid side chains (R groups) of a single polypeptide.

Quaternary Protein Structure

The structural arrangement and association of two or more distinct folded polypeptide subunits into a functional multi-subunit protein complex.

Active Site

The designated catalytic region or binding cleft on an enzyme where substrate molecules specifically dock during a chemical reaction.

Activation Energy

The threshold kinetic energy required to initiate a chemical reaction, which is lowered by the presence of an enzyme catalyst.

Central Dogma

The fundamental concept describing the sequential transfer of genetic instructions from $DNA$ via transcription into $RNA$, which is then translated into functional proteins.

Adenosine Triphosphate (ATP)

The primary energy-transfer nucleotide of the cell, composed of adenine, ribose, and three phosphate groups, which provides quick energy when its terminal phosphate bond is broken.