BIOL 351: Lecture 10

Comprehensive vocabulary flashcards covering bioenergetics, electron transport systems, the citric acid cycle, metabolic pathways, and bacterial cell division.

ATP Synthase (ATPase)

A reversible multiprotein membrane complex that utilizes the energy of the proton motive force ($3\,H^+ = 1\text{ ATP}$) to catalyze ATP formation from ADP and $P_i$, or operates in reverse to generate a PMF.

$F_1$ Complex

The catalytic cytoplasmic multiprotein headpiece of ATP synthase where rotational torque induces conformational changes in the $\beta$ subunits to synthesize ATP.

$F_0$ Complex

The membrane-embedded channel component of ATP synthase consisting of the $a$ subunit and a rotating $c_{12}$ ring that translocates protons across the cytoplasmic membrane.

Respiratory Inhibitors

Molecules such as cyanide ($CN^-$) and carbon monoxide ($CO$) that block electron transfer along the respiratory chain by binding tightly to cytochromes.

Uncouplers

Hydrophobic agents, including dinitrophenol and dicumarol, that make cytoplasmic membranes leaky to protons, preventing ATP formation without inhibiting the electron transport chain itself.

Citric Acid Cycle (CAC)

A cyclic pathway that completely oxidizes two $3\text{-carbon}$ pyruvate units to six molecules of $CO_2$, producing reducing power (NADH and $FADH_2$) and essential carbon intermediates for biosynthesis.

Oxaloacetate

A 4-carbon ($C_4$) intermediate of the citric acid cycle that serves as a direct metabolic branch point for amino acid synthesis.

$\alpha$-Ketoglutarate

A 5-carbon ($C_5$) dicarboxylic acid intermediate in the citric acid cycle that serves as a precursor for amino acid synthesis.

Acetyl-CoA

A 2-carbon ($C_2$) high-energy derivative formed by the decarboxylation of pyruvate that supplies carbons to the citric acid cycle or branches into fatty acid synthesis.

Succinyl-CoA

A 4-carbon ($C_4$) intermediate of the citric acid cycle utilized by cells as an essential precursor in porphyrin synthesis.

Aerobic Respiration Energy Yield

The net chemical generation of energy from one glucose molecule oxidizing to $6\,CO_2$ and $6\,H_2O$, yielding a net of $38\text{ ATP}$ ($4\text{ ATP}$ via SLP and $34\text{ ATP}$ via oxidative phosphorylation).

Nitrate Reduction

A respiratory pathway under anaerobic conditions in which nitrate ($NO_3^-$) acts as the terminal electron acceptor and is reduced to nitrite ($NO_2^-$) and $H_2O$ by nitrate reductase.

Ralstonia eutropha

A chemolithoautotrophic bacterium that utilizes membrane-bound and soluble hydrogenases to oxidize hydrogen gas ($H_2$), simultaneously generating a proton motive force and reducing power (NADH) to fix $CO_2$.

Soluble Hydrogenase

A cytoplasmic enzyme present in Ralstonia eutropha that reduces $NAD^+$ to NADH using electrons from $H_2$ to support carbon assimilation and cell biosynthesis.

Photoautotroph

A phototrophic organism that harnesses light energy to produce ATP and reduces carbon dioxide ($CO_2$) into organic cell material.

Photoheterotroph

A phototrophic organism that absorbs light to generate ATP and reducing power, while assimilating organic compounds from its environment as its carbon source.

Catabolism

The set of metabolic reactions that break down complex substrates into simpler products, releasing energy conserved in the form of ATP and the proton motive force.

Anabolism

Energy-consuming biosynthetic reactions that utilize ATP, reducing power, and precursor monomers to assemble macromolecules and other cellular constituents.

Binary Fission

The primary mode of bacterial cell replication comprising cell elongation, septum formation, synthesis of new cell walls, and physical separation into two progeny cells.

Bacterial Divisome

A multiprotein division complex assembled at the division septum, containing proteins such as FtsZ, ZipA, FtsA, FtsK, and FtsI to drive cell constriction and cell wall synthesis.

FtsZ

A tubulin-homologous GTPase protein conserved in bacteria and archaea that polymerizes to form a contractile ring at the mid-cell plane to initiate cell division.

Nucleoid Occlusion

DNA replicates before the FtsZ ring forms

MinCD Proteins

Required for identification of the mid-cell point and divide at this point.