General Biology 1: Cell Metabolism & Bioenergetics Vocabulary

Comprehensive vocabulary flashcard set covering 40 key concepts in cellular bioenergetics, thermodynamics, enzymes, photosynthesis, respiration, and fermentation.

Photoautotrophs

Organisms that harvest light energy from the sun to synthesize organic compounds like glucose.

Entropy

A quantitative thermodynamic measure of randomness, disorder, or chaos in a biological system.

Thylakoid Membrane

The specific membrane-enclosed structure inside chloroplasts housing the light-dependent reactions.

Rubisco

The primary enzyme that catalyzes carbon fixation by combining $\text{CO}_2$ with RuBP in the Calvin cycle.

Glycolysis

The universal metabolic pathway occurring in cytoplasm that splits glucose into two 3-carbon pyruvates without requiring oxygen.

Mitochondria

The eukaryotic cell organelle where the Krebs cycle and electron transport chain take place.

ATP Synthase

The membrane enzyme complex that synthesizes ATP driven by the flow of protons down their concentration gradient.

Substrate-level Phosphorylation

The direct metabolic mechanism forming ATP by transferring a phosphate group from a phosphorylated substrate to ADP.

Lactic Acid Fermentation

The pathway occurring in human muscle cells under anaerobic conditions to regenerate $\text{NAD}^+$ without extra ATP yield by producing lactic acid (lactate).

Stomata

Microscopic closable leaf pores that regulate gas exchange ($\text{CO}_2$ and $\text{O}_2$) and water vapor loss in plants.

First Law of Thermodynamics

The law stating that energy cannot be created or destroyed, only converted from one form to another.

Catabolic Pathways

Metabolic pathways that degrade complex organic polymers into monomeric units, releasing net usable energy to power cellular work.

Noncyclic Light-Dependent Pathway

A photosynthetic pathway that produces ATP, NADPH, and releases $\text{O}_2$.

Cyclic Light-Dependent Pathway

A photosynthetic pathway that produces only ATP.

Stroma

The fluid-filled space within the chloroplast where the Calvin cycle (light-independent reactions) occurs.

Alcoholic Fermentation

An anaerobic pathway in yeast that yields ethanol and carbon dioxide as its primary end products.

Final Electron Acceptor

Molecular oxygen ($\text{O}_2$), which serves as the ultimate acceptor of electrons at the terminus of the electron transport chain in aerobic cellular respiration.

Denaturation

The structural alteration of an enzyme's active site caused by high temperatures exceeding its optimum.

Adenosine Triphosphate (ATP)

The primary immediate energy currency for cellular work in living organisms.

Photolysis of Water

The splitting of water ($\text{H}_2\text{O}$) during light-dependent reactions to supply replacement electrons for Photosystem II (PSII).

NADP+ and NAD+

Coenzymes responsible for shuttling high-energy electrons and hydrogen ions ($\text{H}^+$) in cellular metabolic pathways.

PGAL / G3P

The 3-carbon sugar intermediates (glyceraldehyde 3-phosphate) generated during the synthesis phase of the Calvin cycle.

Krebs Cycle (Citric Acid Cycle)

The metabolic stage of aerobic cellular respiration taking place within the mitochondrial matrix.

Electron Transport Chain / Chemiosmosis

The phase of aerobic cellular respiration that yields the highest number of ATP molecules via oxidative phosphorylation.

Active Site

The specific region on an enzyme where substrate molecules bind and catalytic reactions occur.

Carbon Fixation

The metabolic process of incorporating inorganic $\text{CO}_2$ into organic sugar molecules in plants.

Chlorophyll a

The green photosynthetic pigment primarily responsible for absorbing light energy in chloroplasts.

Chemical Oxidation

In oxidation-reduction (redox) reactions, the explicit chemical loss of electrons.

Chemical Reduction

In oxidation-reduction (redox) reactions, the chemical gain of electrons.

Proton Concentration Gradient

The electrochemical gradient formed by proton ($\text{H}^+$) flow that directly drives ATP synthesis through ATP Synthase during chemiosmosis.

Respiratory Carbon Dioxide Output

The total of $6$\,$\text{CO}_2$ molecules produced as metabolic waste per molecule of glucose fully oxidized in aerobic respiration.

Fermentation

An anaerobic metabolic pathway that enables cells to continue generating ATP by regenerating $\text{NAD}^+$ for glycolysis.

Anabolic Reactions

Metabolic processes that construct complex polymers from smaller monomeric building blocks.

Activation Energy Barrier ($E_a$)

The energy barrier lowered by enzymes to speed up chemical reactions without altering net free energy change.

Net Free Energy Change ($ΔG$)

The net overall free energy change of a metabolic reaction, which remains unaffected by enzyme catalysts.

Photosystem I (PSI)

The photosystem that receives electrons from the electron transfer chain and uses light energy to reduce $\text{NADP}^+$ to NADPH.

Photosystem II (PSII)

The photosystem that absorbs light and receives replacement electrons directly from the photolysis of water.

Aerobic Respiration Reactants

Glucose ($\text{C}_6\text{H}_{12}\text{O}_6$) and oxygen ($\text{O}_2$), which serve as required starting materials for aerobic cellular respiration.

Theoretical Maximum Net ATP Yield

The net yield of $36$ to $38$ ATP molecules produced per single glucose molecule fully oxidized during eukaryotic aerobic respiration.

Second Law of Thermodynamics

The thermodynamic principle governing the natural tendency toward increased entropy and disorder in physical and biological systems.