Bioenergetics Flashcards

Vocabulary flashcards for reviewing bioenergetics lecture notes.

Bioenergetics

The study of energy flow through living systems.

Metabolism

The sum of all chemical reactions that occur within a living organism.

Catabolism

The breakdown of complex molecules into simpler ones, releasing energy.

Anabolism

The synthesis of complex molecules from simpler ones, requiring energy.

Redox Reaction

A reaction involving the transfer of electrons between chemical species.

Oxidation

The loss of electrons from a substance.

Reduction

The gain of electrons by a substance.

Mitochondrion

An organelle found in eukaryotic cells; the site of cellular respiration.

Cristae

The inner membrane folds of the mitochondrion, increasing surface area.

Intermembrane space

The space between the inner and outer mitochondrial membranes.

Matrix

The innermost space of the mitochondrion, containing enzymes for the Krebs cycle.

ATP

Adenosine triphosphate; the primary energy currency of cells.

ADP

Adenosine diphosphate; formed when ATP loses a phosphate group.

AMP

Adenosine monophosphate; formed when ATP loses two phosphate groups.

Phosphoric anhydride bond

A high-energy chemical bond formed when two phosphate groups are joined.

Universal carrier

A molecule that serves as a carrier of phosphate groups.

Citric Acid Cycle

A metabolic pathway that oxidizes acetyl-CoA, releasing energy and carbon dioxide.

Tricarboxylic Acid Cycle (TCA)

Another name for the Citric Acid Cycle.

Electron Transport Chain

A series of protein complexes that transfer electrons from electron donors to electron acceptors, powering ATP synthesis.

Oxidative Phosphorylation

The process of generating ATP using the energy released by the electron transport chain and chemiosmosis.

NAD+

Nicotinamide adenine dinucleotide; a coenzyme involved in redox reactions.

NADH

The reduced form of NAD+, carrying electrons.

FAD

Flavin adenine dinucleotide; a coenzyme involved in redox reactions.

FADH2

The reduced form of FAD, carrying electrons.

Coenzyme A (CoA)

A coenzyme that carries acetyl groups.

Intermediate

An intermediate compound formed during a multi-step chemical reaction.

Glycolysis

The breakdown of glucose into pyruvate.

Pyruvate

A three-carbon molecule produced during glycolysis.

Cytosol

The fluid portion of the cytoplasm.

Acetyl CoA

The molecule formed when pyruvate combines with coenzyme A.

Energy Investment Stage

The stage of glycolysis that requires ATP in order to occur.

Energy Harvesting Stage

The stage of Glycolysis that generates ATP

Citrate

A six-carbon molecule intermediate within the Citric Acid Cycle

Ketoglutarate

A five-carbon molecule intermediate within the Citric Acid Cycle

Succinate

A four-carbon molecule intermediate within the Citric Acid Cycle

Krebs Cycle

A series of chemical reactions used to release stored energy through oxidation of acetyl-CoA, derived from carbohydrates, fats, and proteins

Chemiosmosis

Movement of ions across a semipermeable membrane, down their electrochemical gradient.

Electron donor

A molecule that donates electrons in the electron transport chain.

Electron acceptor

A molecule that accepts electrons in the electron transport chain.

Proton Gradient

An electrochemical gradient formed by the difference in proton concentration across a membrane.

ATP Synthase

The enzyme that synthesizes ATP using the energy of a proton gradient.

Coenzyme Q

A lipid-soluble electron carrier in the electron transport chain.

Cytochrome C

A protein containing heme, that acts as an electron carrier in the electron transport chain.

Complex

A protein weakly connected to other molecules or proteins.

Ubiquinone

A lipid soluble substance that accepts electrons from Complex I and Complex II.

Chemiosmotic Theory

Peter Mitchell's theory suggesting that the proton gradient across the inner mitochondrial membrane, drives ATP Synthesis.

Conventional Ratio

Oxidation of NADH gives approximately 3 ATP, FADH2 gives 2 ATP.

Energy Yield

The quantity of ATP derived from the complete metabolism of glucose.

Pathway

A sequence of chemical reactions that occur, resulting in a product.

Catabolism

Breakdown of biomolecules for ATP production.

Glycolysis

The series of 10 enzyme catalyzed reactions where glucose is oxidized to 2 pyruvate molecules.

A-D-Glucose-6-phosphate

Feedback inhibitor for hexokinase preventing excessive phosphorylation.

Phosphofructokinase

Regulatory enzyme in glycolysis, activity increases to accelerate glycolysis.

Fermentation

Production of ethanol in anaerobic conditions.

Aerobic Conditions

Oxidative decarboxylation produces acetyl group of acetyl CoA.

Glycerol

Entering glycolysis via dihydroxyacetone phosphate.

Fatty acids

Principal storage form of energy for organisms.

Beta-Oxidation

Cleaves carbon atoms, 2 at a time from carboxyl end of a fatty acid.

Hydrocarbon Chains

Fatty acid in triglyceride's principal storage form is highly reduced.

Oxidative Deamination

The removal of an amino group from an amino acid.

Ammonia

Toxic if accumulated, the liver converts this into urea.

Urea

Excreted in urine, produced when liver converts ammonia.

Nitrogenous Waste

An increase may cause renal damage.

Condensation

A reaction in which the high-energy thioester bond of acetyl CoA is broken to drive the formation of citrate.

Citrate Synthase

An enzyme that catalyzes the condensation of acetyl CoA and oxaloacetate to form citrate.

Dehydration

The removal of water from a molecule.

Rehydration

The addition of water to a molecule.

Aconitase

An enzyme that catalyzes the dehydration and rehydration of citrate to form isocitrate.

Decarboxylation

The oxidation of a molecule accompanied by the release of carbon dioxide.

Isocitrate Dehydrogenase

An enzyme that catalyzes the oxidation and decarboxylation of isocitrate to form alpha-ketoglutarate.

alpha-ketoglutarate dehydrogenase complex

A multi enzyme complex that catalyzes the oxidative decarboxylation of α-ketoglutarate to succinyl-CoA

Energy-Yielding Step

A reaction yielding GTP.

Succinyl-CoA Synthetase

This enzyme catalyzes the conversion of succinyl-CoA to succinate

Succinate Dehydrogenase

An enzyme that catalyzes the oxidation of succinate to fumarate.

Fumarase

An enzyme that catalyzes the hydration of fumarate to L-malate.

Malate Dehydrogenase

An enzyme that catalyzes the oxidation of malate to oxaloacetate.

Citrate Synthase

Inhibited by ATP, NADH, and succinyl CoA; also product inhibition by citrate.

Isocitrate Dehydrogenase

Activated by ADP and NAD+, inhibited by ATP and NADH

α-Ketoglutarate Dehydrogenase Complex

Inhibited by ATP, NADH, and succinyl CoA; activated by ADP and NAD+

Electron Transport Chain (ETC)

Pathway that forms ATP as a result of the transferring of electrons from NADH & FADH2 to O2.

Oxidative Phosphorylation

Made up of the electron transport chain (ETC) and chemiosmosis

Electrons

Supercharges protein complexes (I, III, and IV) and enables them to pump out hydrogen ions into the intermembrane space.

Proton Gradient

Difference in the concentrations of H ions or protons between the mitochondrial matrix and intermembrane space

Oxygen

Sits at the end of the electron transport chain, where it accepts electrons and picks up protons to form water.

NADH

Donates electrons to complex I, turning back into NAD

FADH2

Feeds electrons into the transport chain through complex II

Protons

Pumped across the inner membrane to the intermembrane space.

FMN

Receives the hydrogen from NADH and 2 electrons.

Proton Gradient

This is created across the inner mitochondrial membrane, due to oxidation .

ATP Synthase

Protons flow back into the matrix through channels in the F0 unit, also known as this.

ATP Synthase

The enzyme that makes ATP.

Functions of Oxygen Gas

oxidize NADH to NAD+ and FADH2 to FAD so that these molecules can return to participate in the citric acid cycle

Pathway

Refers to the sequence of steps that a chemical reaction undergoes from reactants to products.

Reaction Pathway

Sequence of steps that a chemical reaction undergoes from reactants to products.

Pyruvate

Product of glucose through glycolysis.

Glucose to Pyruvate

Oxidation of glucose through glycolysis.

Glycerol to Dihydroxyacetone phosphate

Oxidation of glycerol through glycolysis.

Fatty Acid to Acetyl CoA NADH FADH2

b-Oxidation yields.

Glucose 6-Phosphate to Fructose

Isomerization of glucose 6-phosphate, acts as a feedback inhibitor.

Oxidation of D-glyceraldehyde 3-phosphate

Marks the beginning of the energy payoff phase in glycolysis