BIOL 1406 Exam 3 Review: Metabolism, Cellular Respiration, and Photosynthesis

Comprehensive vocabulary review flashcards for BIOL 1406 Exam 3, covering Chapter 8 (Metabolism), Chapter 9 (Cellular Respiration and Fermentation), and Chapter 10 (Photosynthesis).

Metabolism

The totality of an organism's chemical reactions, consisting of catabolic and anabolic pathways that manage the material and energy resources of the cell.

Anabolism

Metabolic pathways that consume energy to synthesize complex molecules from simpler ones, often involving dehydration reactions.

Catabolism

Metabolic pathways that release energy by breaking down complex molecules into simpler compounds, often involving hydrolysis reactions.

Dehydration Reaction

A chemical reaction in which two molecules covalently bond to each other with the removal of a water molecule ($H_2O$).

Hydrolysis

A chemical process that splits molecules by the enzymatic addition of water ($H_2O$).

Kinetic Energy

The energy associated with the relative motion of objects.

Thermal Energy

Kinetic energy associated with the random movement of atoms or molecules.

Potential Energy

Energy that matter possesses because of its location or spatial arrangement.

Chemical Energy

Potential energy available for release during a chemical reaction.

Heat

Thermal energy in transfer from one body of matter to another.

First Law of Thermodynamics

The principle stating that energy can be transferred and transformed, but it cannot be created or destroyed.

Second Law of Thermodynamics

The principle stating that every energy transfer or transformation increases the entropy of the universe.

Entropy ($\Delta S$)

A thermodynamic measure of molecular disorder or randomness within a system.

Enthalpy ($\Delta H$)

The total heat or thermal energy content of a thermodynamic system.

Free Energy Change ($\Delta G$)

The portion of a system's energy that can perform work at constant temperature and pressure, defined by $\Delta G = \Delta H - T\Delta S$.

Exergonic Reaction

A spontaneous chemical reaction characterized by a net release of free energy where $\Delta G < 0$.

Endergonic Reaction

A nonspontaneous chemical reaction that absorbs free energy from its surroundings where $\Delta G > 0$.

Phosphorylation

The covalent transfer of a phosphate group to a molecule, often conferring energy or altering its reactivity.

ATP Cycle

The continual process of regenerating ATP by adding inorganic phosphate to ADP using energy derived from catabolism, alternating with ATP hydrolysis to release energy for cellular work.

Active Site

The specific region of an enzyme molecule where the substrate binds and where catalysis takes place.

Enzyme-Substrate Complex

A temporary complex formed when an enzyme binds to its specific substrate molecule.

Cofactors and Coenzymes

Non-protein helpers required for enzymatic activity, with inorganic helpers referred to as cofactors and organic helpers designated as coenzymes.

Competitive Inhibitor

A substance that reduces the activity of an enzyme by mimicking the substrate and binding directly to the active site.

Noncompetitive Inhibitor

A substance that impedes enzyme activity by binding to a location away from the active site, altering the enzyme's conformation.

Feedback Inhibition

A method of metabolic control in which the end product of a pathway acts as an inhibitor of an enzyme functioning early in that same pathway.

Facultative Anaerobe

An organism that makes enough ATP to survive using either aerobic respiration in the presence of $O_2$ or fermentation in the absence of $O_2$.

Oxidation

The complete or partial loss of electrons from a substance in a redox reaction.

Reduction

The complete or partial addition of electrons to a substance in a redox reaction.

Substrate-Level Phosphorylation

The enzyme-catalyzed formation of ATP by the direct transfer of a phosphate group to ADP from an intermediate substrate.

Oxidative Phosphorylation

The production of ATP using energy derived from the redox reactions of an electron transport chain and chemiosmosis.

Glycolysis

A cytoplasmic pathway that breaks down glucose into two molecules of pyruvate, organized into an energy investment phase and an energy payoff phase.

Citric Acid Cycle (Krebs Cycle)

A metabolic cycle within the mitochondrial matrix that oxidizes organic fuel derived from pyruvate, generating $NADH$, $FADH_2$, ATP, and releasing $CO_2$.

Proton-Motive Force

The potential energy stored in the form of a proton electrochemical gradient, generated by pumping $H^+$ across a biological membrane.

Chemiosmosis

An energy-coupling mechanism that uses energy stored in an $H^+$ gradient across a membrane to drive cellular work, specifically ATP synthesis via ATP synthase.

ATP Synthase

A membrane-spanning enzyme complex that utilizes the flow of $H^+$ down its electrochemical gradient to catalyze the synthesis of ATP from ADP and inorganic phosphate.

Alcohol Fermentation

A catabolic pathway consisting of glycolysis followed by the conversion of pyruvate into ethyl alcohol, regenerating $NAD^+$ while releasing $CO_2$.

Lactic Acid Fermentation

A catabolic pathway consisting of glycolysis followed by the reduction of pyruvate to lactate, regenerating $NAD^+$ without producing $CO_2$.

Autotroph

An organism that synthesizes organic molecules from inorganic raw materials using energy from light or chemicals, utilizing inorganic $CO_2$ as its carbon source.

Heterotroph

An organism that obtains organic food molecules by consuming other organisms, relying on organic compounds for its carbon source.

Thylakoid

A flattened, membranous sac inside a chloroplast containing photosynthetic pigments and electron transport chains where the light reactions occur.

Stroma

The dense fluid within the chloroplast surrounding the thylakoid membranes, where the Calvin cycle takes place.

Light Reactions

The solar-powered first stage of photosynthesis occurring in the thylakoids, which converts light energy into ATP and $NADPH$ while splitting $H_2O$ and releasing $O_2$.

Photophosphorylation

The process of generating ATP from ADP and inorganic phosphate by means of a proton-motive force driven by light reactions in chloroplasts.

Calvin Cycle

The light-independent second stage of photosynthesis occurring in the stroma, which fixes $CO_2$ and utilizes ATP and $NADPH$ to produce carbohydrate molecules.

Carbon Fixation

The initial incorporation of inorganic carbon from $CO_2$ into an organic compound.

Rubisco

Ribulose bisphosphate carboxylase-oxygenase; the enzyme that catalyzes the attachment of $CO_2$ to RuBP during the first phase of the Calvin cycle.

Ribulose Bisphosphate (RuBP)

A five-carbon sugar molecule that serves as the initial $CO_2$ acceptor in the carbon fixation phase of the Calvin cycle.

Glyceraldehyde 3-Phosphate (G3P)

The three-carbon carbohydrate produced directly from the Calvin cycle, requiring the input and fixation of $3$ molecules of $CO_2$ per net molecule produced.