Microbial Control and Metabolic Pathways

Vocabulary practice flashcards covering physical and chemical control of microorganisms, enzymatic regulation, and central catabolic and anabolic pathways in microbial metabolism.

Sterilization

The complete removal or destruction of all viable microorganisms, including bacterial endospores and viruses, from an object or environment.

Disinfection

The elimination of most or all pathogenic microorganisms on or within inanimate objects, typically not killing bacterial endospores.

Antiseptic

A non-toxic antimicrobial formulation formulated to be safely applied directly onto living skin or mucosal tissues to reduce microbial numbers.

Pasteurization

A brief heat treatment used to significantly reduce spoilage organisms and eradicate pathogenic microbes without degrading product quality.

Degerming

The mechanical removal of microbes from a limited area of skin or tissue, such as scrubbing hands with soap or cleansing an injection site with alcohol.

Sanitation

A cleaning and treatment process that substantially lowers microbial populations to levels meeting public health standards.

Nosocomial Infection

An infectious disease acquired by an individual during hospitalization or medical care in a clinical facility.

Decimal Reduction Time ($D$ value)

The time in minutes under a specified set of conditions required to reduce a viable microbial population by $90\%$.

Bacteriostatic

A property of an agent or physical condition (such as refrigeration) that arrests bacterial growth and reproduction without killing the cells.

Bactericidal

A property of a chemical substance or physical treatment that directly kills bacteria.

Tuberculocidal

A chemical or physical treatment capable of killing Mycobacterium species, which have lipid-rich, waxy cell walls resistant to conventional disinfectants.

Critical Items

Medical and surgical instruments that directly penetrate sterile body tissues or the bloodstream, requiring absolute sterilization.

Semi-critical Items

Instruments that come into contact with mucous membranes or non-intact skin without penetrating sterile tissues, requiring high-level disinfection.

Non-critical Items

Items that contact only intact skin (such as stethoscopes and blood pressure cuffs), carrying a low risk of transmitting infection.

Autoclave

A sterilization apparatus utilizing pressurized steam (typically at $121\,^{\circ}\text{C}$ and $15\,\text{psi}$) that must make direct contact with all surfaces of an object.

Non-ionizing Radiation

Electromagnetic radiation, such as ultraviolet light, that damages microbes by inducing thymine dimers in their DNA; it lacks penetration depth and is used primarily for surface decontamination.

Ionizing Radiation

High-energy radiation (such as gamma rays and X-rays) that penetrates deep into materials to generate reactive radicals and shatter microbial DNA, achieving sterilization.

Metabolism

The comprehensive collection of controlled biochemical reactions occurring within an organism's cells to facilitate growth, repair, and reproduction.

Catabolism

Exergonic metabolic pathways that break down complex organic molecules into simpler units using hydrolysis reactions, releasing energy to synthesize ATP and generating precursor metabolites.

Anabolism

Endergonic biosynthetic pathways that assemble complex cellular macromolecules from simpler precursor subunits using dehydration synthesis and consuming ATP.

Enzyme

A biological macromolecular catalyst (primarily protein) that increases chemical reaction rates without being consumed by lowering activation energy.

Substrate-Level Phosphorylation

A mode of ATP synthesis wherein a high-energy phosphate group is directly transferred from a phosphorylated organic intermediate to ADP, independent of a membrane or proton gradient.

Oxidative Phosphorylation

A highly productive ATP-generating process driven by an electron transport chain along a cellular membrane, creating a proton gradient that powers an ATPase.

Dephosphorylation

The enzymatic removal of an inorganic phosphate group from an organic compound via a hydrolysis reaction.

Cofactor

A non-protein helper substance (such as inorganic metal ions like $\text{Mg}^{2+}$, $\text{Zn}^{2+}$, or $\text{Cu}^{2+}$) essential for an enzyme's catalytic function.

Coenzyme

An organic cofactor, often derived from dietary vitamins, that functions as a loosely bound transient carrier of functional chemical groups or electrons (e.g., $\text{NAD}^+$, $\text{FAD}$).

Allosteric Site

A specialized non-catalytic regulatory region on an enzyme separate from the active site; binding of a regulatory effector alters enzyme conformation to activate or inhibit catalytic activity.

Competitive Inhibitor

A chemical agent whose structure closely mimics the natural substrate, allowing it to compete directly for and bind to the enzyme's active site (e.g., sulfa drugs competing with PABA).

Feedback Inhibition

A cellular control mechanism in which an accumulating pathway end product acts as an allosteric inhibitor on an early enzyme in the pathway, shutting down further synthesis.

Glycolysis

The primary cytosolic central metabolic pathway that oxidizes one molecule of glucose into two molecules of pyruvate, yielding a net gain of $2\,\text{ATP}$ and $2\,\text{NADH}$.

Pentose Phosphate Pathway

A catabolic pathway operating alongside glycolysis that breaks down glucose to yield precursor metabolites and reducing power for the biosynthesis of nucleic acids and amino acids.

Transition Step

The intermediate reaction linking glycolysis to the Krebs cycle, converting two pyruvate molecules into two acetyl-CoA while yielding $2\,\text{NADH}$ and $2\,\text{CO}_2$ without producing ATP.

Tricarboxylic Acid (TCA) Cycle

A cyclical metabolic pathway that completes the oxidation of acetyl-CoA, producing $2\,\text{ATP}$, $6\,\text{NADH}$, $2\,\text{FADH}_2$, and $4\,\text{CO}_2$ per glucose molecule while generating amino acid precursors.

Proton Motive Force

The electrochemical potential energy stored across a biological membrane generated by the active pumping of hydrogen ions ($\text{H}^+$) to the exterior during electron transport.

ATPase

A membrane-bound enzyme complex that utilizes the electrochemical energy of the proton motive force to synthesize ATP from ADP and inorganic phosphate.

Fermentation

An anaerobic metabolic process where cells oxidatively break down glucose using glycolysis alone, transferring electrons from $\text{NADH}$ onto pyruvate or an organic derivative to regenerate $\text{NAD}^+$.

Lactic Acid Fermentation

A fermentation pathway wherein pyruvate directly serves as the terminal electron acceptor, accepting electrons from $\text{NADH}$ to produce lactate (lactic acid) and free $\text{NAD}^+$.

Ethanol Fermentation

A fermentation process where pyruvate is decarboxylated to acetaldehyde, which subsequently accepts electrons from $\text{NADH}$ to yield ethanol and $\text{CO}_2$.

Methyl Red (MR) Test

A diagnostic test used to detect mixed acid fermentation; a red coloration upon addition of methyl red indicator indicates persistent high acidity (e.g., Escherichia coli is MR+).

Voges-Proskauer (VP) Test

A diagnostic test identifying 2,3-butanediol fermenters by detecting acetoin, a neutral pathway intermediate (e.g., Enterobacter aerogenes is VP+).

Lipase

An extracellular enzyme that catabolizes triglycerides into free glycerol, which is converted to glyceraldehyde-3-phosphate, and fatty acids, which are oxidized to acetyl groups.

Deamination

The enzymatic removal of the amino group ($-\text{NH}_2$) from an amino acid, yielding an organic acid intermediate that can directly enter the TCA cycle.