Microbial Metabolism

Vocabulary practice flashcards covering the key concepts, pathways, enzyme mechanisms, and energetic processes of microbial metabolism.

Metabolism

The sum total of all chemical reactions in a cell, encompassing both the synthesis of new cell parts and the harvesting of energy to power cellular reactions.

Catabolism

The set of metabolic processes that degrade compounds to release energy, which cells capture to produce $ATP$ and precursor metabolites.

Anabolism

The biosynthetic processes in a cell that consume $ATP$ and precursor metabolites to synthesize and assemble macromolecules and cellular structures.

Precursor Metabolites

Intermediate molecules generated during catabolic reactions that are used as building subunits for biosynthesis.

Metabolic Pathway

A sequence of sequential chemical reactions that converts a starting compound into an end product, organized in linear, branched, or cyclical arrangements.

Enzyme

A biological catalyst that accelerates the rate of specific chemical reactions in cells by lowering the activation energy ($E_a$) without being consumed in the process.

Active Site

The region on an enzyme surface to which a substrate binds weakly, inducing a slight shape change that destabilizes existing bonds to form new ones.

Adenosine Triphosphate (ATP)

The main energy currency of the cell, formed by adding inorganic phosphate ($P_i$) to $ADP$ using catabolic energy, and hydrolyzed to release energy for anabolic reactions.

Terminal Electron Acceptor

The final molecule that accepts electrons transferred from an electron donor or energy source during metabolic processes.

Redox Reactions

Coupled oxidation-reduction reactions where one substance loses electrons (is oxidized) and another substance gains those electrons (is reduced), typically moving as electron-proton pairs or hydrogen atoms.

Reducing Power

The energy-rich capacity of reduced electron carriers (such as $NADH$, $NADPH$, and $FADH_2$) to readily donate electrons to recipient molecules and raise their energy state.

Central Metabolic Pathways

The primary set of catabolic pathways—including glycolysis, the pentose phosphate pathway, and the tricarboxylic acid (TCA) cycle—that oxidize glucose to generate $ATP$, reducing power, and precursor metabolites.

Glycolysis

A central metabolic pathway that oxidizes $1$ molecule of glucose to $2$ molecules of pyruvate, yielding a net of $2\text{ ATP}$ by substrate-level phosphorylation and $2\text{ NADH}$.

Tricarboxylic Acid (TCA) Cycle

A cyclical central pathway that completes the oxidation of pyruvate derivatives to carbon dioxide, producing $2\text{ CO}_2$, $2\text{ ATP}$, $6\text{ NADH}$, and $2\text{ FADH}_2$ per glucose molecule.

Chemiosmotic Theory

The scientific concept proposed by British scientist Peter Mitchell in 1961 stating that electron transport chains generate a proton motive force that drives $ATP$ synthesis by $ATP$ synthase.

Peter Mitchell

The British scientist who conducted years of self-funded research to propose the chemiosmotic theory in 1961 and was awarded the Nobel Prize in 1978.

Electron Transport Chain (ETC)

A membrane-embedded assembly of electron carriers that gradually passes electrons from $NADH$ or $FADH_2$ to a terminal electron acceptor while pumping protons ($H^+$) across the membrane.

Proton Motive Force

An electrochemical gradient of protons ($H^+$) across the cell membrane created by the electron transport chain, used to power $ATP$ synthesis, bacterial flagellar rotation, and active transport.

Oxidative Phosphorylation

The process of synthesizing $ATP$ using the electrochemical energy of the proton motive force driven by the electron transport chain and catalyzed by $ATP$ synthase.

Fermentation

An anaerobic metabolic process used when cellular respiration is not an option, which uses pyruvate or a derivative as a terminal electron acceptor to regenerate $NAD^+$ without producing $ATP$.

Facultative Anaerobe

An organism, such as Escherichia coli, capable of utilizing cellular respiration when suitable electron acceptors are available or switching to fermentation when they are absent.

Streptococcus pneumoniae

A bacterial species that lacks an electron transport chain, making fermentation its only available metabolic pathway for regenerating oxidized electron carriers.