Energy of Life: Bioenergetics and Metabolism

A comprehensive set of vocabulary flashcards covering key terms and concepts from the lecture on bioenergetics and metabolism.

Bioenergetics

The study of how energy flows through living organisms.

Energy

The capacity to do work.

Kinetic energy

Energy associated with motion.

Thermal energy

Kinetic energy associated with random movement of atoms or molecules.

Potential energy

The energy that matter possesses because of its location or structure.

Chemical energy

Potential energy available for release in a chemical reaction.

Thermodynamics

The study of energy transformations.

First law of thermodynamics

The energy of the universe is constant; energy can be transferred and transformed but not created or destroyed.

Entropy

A measure of disorder in the universe.

Second law of thermodynamics

Energy transfers and transformations increase entropy.

Exergonic reaction

Reactions that release energy during the catabolism of biological molecules.

Free energy (ΔG)

The portion of a system’s energy that can perform work when temperature and pressure are uniform.

Endergonic reaction

A nonspontaneous reaction that absorbs free energy from the surroundings.

Metabolic pathway

A series of chemical reactions in which a reactant yields a product, catalyzed by an enzyme.

Catalysts

Substances that increase the rate of a reaction without being chemically changed.

Enzymes

Biological protein-based catalysts that lower the energy of activation for chemical reactions.

Cofactors

Nonprotein enzyme helpers required by some enzymes to react.

Coenzyme

An organic cofactor, often derived from vitamins.

Saturation point

The point at which all active sites of an enzyme are filled with substrates.

Enzyme denaturing

The process by which an enzyme loses its native shape and functionality due to environmental changes.

Competitive inhibition

Inhibition that occurs when a mimic competes for the active site of an enzyme.

Noncompetitive inhibition

Inhibition that occurs when a molecule binds to an allosteric site, not the active site.

Irreversible inhibition

Permanent inhibition that cannot be overcome.

Oxidation

The process by which a substance loses electrons.

Reduction

The process by which a substance gains electrons.

Electron carriers

Molecules that transport electrons; examples include NAD+, NADP+, and FAD.

Substrate-level phosphorylation

The direct addition of a phosphate group from a substrate to ADP to form ATP.

Oxidative phosphorylation

ATP generation through electron transport and chemiosmosis.

Photophosphorylation

The use of light energy to generate ATP.

Glycolysis

The conversion of glucose into pyruvate through a series of enzymatic reactions.

Citric acid cycle

Also known as the Krebs cycle, a key metabolic pathway that generates electron carriers.

Electron transport chain

A series of protein complexes that transfer electrons and generate ATP.

Chemiosmosis

The process of using a proton gradient to drive ATP synthesis.

Fermentation

A metabolic process that converts sugar to acids, gases, or alcohol in the absence of oxygen.

Photosynthesis

The process that converts solar energy into chemical energy.

Stomata

Small openings on the leaf surface through which gases enter and exit.

Chloroplasts

Cell organelles where photosynthesis occurs.

Chlorophyll

The pigment responsible for absorbing light energy during photosynthesis.

Light reactions

The steps of photosynthesis that capture light energy and convert it into chemical energy.

Calvin cycle

The light-independent reactions that convert CO2 into sugar.

Electron acceptor

A molecule that receives an excited electron during photosynthesis.

Photosystem II (PS II)

The first photosystem in the light reaction that absorbs light at 680 nm.

Photosystem I (PS I)

The second photosystem that absorbs light at 700 nm.

Cyclic electron flow

An electron flow pathway that uses only photosystem I to produce ATP.

Noncyclic electron flow

The primary pathway of photosynthesis that generates ATP and NADPH.

Proton gradient

A difference in proton concentration across a membrane used to synthesize ATP.

Rubisco

The enzyme that catalyzes the first step of the Calvin cycle.

Ribulose bisphosphate (RuBP)

The CO2 acceptor that is regenerated in the Calvin cycle.

Glyceraldehyde 3-phosphate (G3P)

A three-carbon sugar produced in the Calvin cycle.

Chlorophyll a

The main pigment involved in photosynthesis, absorbing light primarily in the blue and red wavelengths.

Carotenoids

Accessory pigments that protect plants and aid in photosynthesis.

Photon energy

The energy carried by photons, important for photosynthesis.

Fluorescence

The emission of light by a substance that has absorbed light; occurs when electrons return to ground state.

Cyanide poisoning

A condition that inhibits electron transport, restricting ATP production.

Activation energy

The minimum energy required to start a chemical reaction.

Decarboxylation

The removal of a carboxyl group from a molecule, releasing CO2.

Energy of activation

The energy required to initiate a reaction.

Photosynthetic efficiency

The effectiveness of photosynthesis in converting light energy to chemical energy.

Light-dependent reactions

Reactions that require light and occur in the thylakoids of chloroplasts.

Light-independent reactions

Reactions not requiring light, taking place in the stroma of chloroplasts.

Thylakoids

Membrane-bound structures within chloroplasts where light reactions occur.

Stroma

The fluid-filled space surrounding thylakoids in chloroplasts.

Chloroplasts vs Mitochondria

Chloroplasts convert light energy to chemical energy, while mitochondria convert chemical energy from food to ATP.

G3P formation

The result of the Calvin cycle where sugar is synthesized from CO2.

Electromagnetic spectrum

The range of all types of electromagnetic radiation.

Visible light

The portion of the electromagnetic spectrum visible to the human eye, essential for photosynthesis.

Cyclic vs Noncyclic flow

Cyclic flow produces only ATP, while noncyclic flow produces ATP and NADPH.

Photosystems

Clusters of chlorophyll and proteins that capture light energy during photosynthesis.

Light energy

Energy from the sun that drives the process of photosynthesis.

Chemiosmotic potential

The potential energy stored in a proton motive force used to drive ATP synthesis.

ATP synthase

An enzyme that synthesizes ATP during chemiosmosis.

Metabolic stages

The series of processes during cellular respiration including glycolysis, citric acid cycle, and oxidative phosphorylation.

Photosynthesis summary equation

6 CO2 + 12 H2O + Light energy -> C6H12O6 + 6 O2 + 6 H2O.

Calvin cycle phases

1. Carbon fixation 2. Reduction 3. Regeneration.