Microbiology Lecture 1: The Microbial World and Microbial Fundamentals

A complete set of vocabulary flashcards covering key terms and concepts from microbiology lecture notes, including historical principles, chemical foundations, cell structures, taxonomy, and microbial metabolism.

Microorganisms

Organisms that are too small to be seen with the unaided eye.

Spontaneous Generation

The hypothesis that life arises from nonliving matter, requiring a vital force.

Biogenesis

The hypothesis that living cells arise only from preexisting living cells.

Germ Theory of Disease

The principle that specific infectious diseases are caused by specific microorganisms.

Koch's Postulates

A series of experimental steps used to establish a direct causal relationship between a specific microbe and a specific disease.

Taxonomy

The biological science of classifying organisms into defined groups based on shared characteristics.

Systematics

Also known as phylogeny, the study of the evolutionary history and relationships of organisms.

Cations

Positively charged ions that are formed when an atom loses one or more electrons.

Anions

Negatively charged ions that are formed when an atom gains one or more electrons.

Ionic Bonds

Chemical attractions between oppositely charged ions formed when one atom transfers electrons to another.

Covalent Bonds

Strong chemical bonds formed when two atoms share one or more pairs of electrons.

Hydrogen Bonds

Weak chemical bonds formed when a hydrogen atom covalently bonded to an oxygen or nitrogen atom is attracted to another oxygen or nitrogen atom in another molecule.

Endergonic Reactions

Chemical reactions that absorb energy from their surroundings.

Exergonic Reactions

Chemical reactions that release energy to their surroundings.

Anabolism

The synthesis of complex organic molecules within a cell, an endergonic process requiring energy and building blocks.

Catabolism

The breakdown of complex organic molecules into simpler ones within a cell, an exergonic process releasing energy.

Isomers

Molecules that possess the exact same chemical formula but differ in their structural arrangement.

Peptidoglycan

A complex polymer consisting of repeating disaccharides ($N\text{-acetylglucosamine}$ and $N\text{-acetylmuramic acid}$) cross-linked by short polypeptides that forms the bacterial cell wall.

Monomorphic

Refers to bacteria that maintain a single, constant cellular shape.

Pleomorphic

Refers to bacteria that can naturally exist in multiple distinct shapes.

Capsule

An organized glycocalyx structure firmly attached external to the bacterial cell wall that prevents phagocytosis and enhances virulence.

Slime Layer

An unorganized and loosely attached glycocalyx structure external to the bacterial cell wall that protects against dehydration and nutrient loss.

Axial Filaments

Also called endoflagella, bundles of fibrils anchored at one end of a spirochete that wrap around the cell and rotate to induce a corkscrew movement.

Fimbriae

Hairlike bacterial appendages that allow cells to adhere to surfaces, fluids, and host tissues.

Pili

Bacterial appendages involved in motility (twitching or gliding) and the transfer of DNA between cells during conjugation.

Teichoic Acids

Anionic polymers present in Gram-positive cell walls that regulate cation movement, prevent cell wall breakdown, and provide antigenic specificity.

Lipopolysaccharide (LPS)

A major constituent of the outer membrane of Gram-negative bacteria, composed of Lipid A (endotoxin), core polysaccharide, and O polysaccharide antigen.

Periplasm

The gel-like space located between the plasma membrane and outer membrane in Gram-negative bacteria containing peptidoglycan and digestive enzymes.

Endospores

Dormant, highly resistant resting cells produced by bacteria such as Bacillus and Clostridium to withstand nutrient depletion, extreme heat, chemicals, and radiation.

Sporulation

The process of endospore formation within a vegetative bacterial cell when conditions become unfavorable.

Germination

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

Activation Energy

The minimum collision energy required for a chemical reaction to take place.

Apoenzyme

The protein component of an enzyme, which is catalytically inactive on its own until bound to a cofactor.

Cofactor

A nonprotein molecule or ion (such as metallic ions or coenzymes) required for an apoenzyme to function.

Coenzyme

An organic cofactor (such as $\text{NAD}^+$, $\text{NADP}^+$, $\text{FAD}$, or Coenzyme A) that assists enzyme activity.

Holoenzyme

A complete, catalytically active enzyme consisting of an apoenzyme bound to its cofactor.

Competitive Inhibitors

Molecules that bind directly to an enzyme's active site, competing with the substrate for binding.

Noncompetitive Inhibitors

Inhibitors that bind to an allosteric site on an enzyme, altering the active site shape so the substrate cannot bind.

Feedback Inhibition

A metabolic regulation mechanism where the end-product of a pathway allosterically inhibits an enzyme operating early in that pathway.

Oxidation

The removal or loss of electrons from an atom or molecule.

Reduction

The gain of electrons by an atom or molecule.

Substrate-Level Phosphorylation

The generation of ATP by the direct transfer of a high-energy phosphate group from a phosphorylated organic compound to ADP.

Oxidative Phosphorylation

The production of ATP using energy released as electrons pass down an electron transport chain to a final electron acceptor.

Photophosphorylation

The synthesis of ATP using light energy in photosynthetic cells via an electron transport chain.

Glycolysis

The oxidation of one glucose molecule into two pyruvic acid molecules, producing a net yield of $2\text{ ATP}$ and $2\text{ NADH}$.

Fermentation

An anaerobic metabolic process that extracts energy from organic molecules without using the Krebs cycle or ETC, utilizing an internal organic molecule as final electron acceptor.

Amphibolic Pathways

Dual-purpose metabolic pathways that function simultaneously in both catabolism and anabolism.