Bootcamp.com - Cellular Energy

Catabolic processes

These processes break down large macromolecules into smaller pieces and usually release energy in the form of ATP.

Anabolic processes

These processes extract energy from ATP and use it to build larger, more complex macromolecules.

Chemical energy

A unique type of potential energy where chemical bonds serve as a store of internal energy and can be used to do work.

Heat

The most common form of 'non-useful' energy release.

Gibbs free energy (G)

This measures a system's useful, work-performing energy.

Free energy change (ΔG)

This describes a system's energy as it progresses from an initial to a final state.

Enthalpy (H)

The energy associated with molecular bond energies.

Bond energy difference

Change in enthalpy (ΔH) is the difference between the initial and final states of a reaction.

Released; absorbed

A negative ΔH means that heat is released, while a positive ΔH implies that heat is absorbed.

-ΔG; exergonic

Catabolic reactions release free energy, so they are an example of an exergonic reaction.

Exergonic reactions

These reactions mean that free energy is exiting the system.

Spontaneous

Exergonic reactions are characterized as spontaneous.

+ΔG; endergonic

Anabolic reactions absorb free energy, making them an example of an endergonic reaction.

Endergonic reactions

These reactions are characterized as non-spontaneous.

Negative

If ∆G is negative, the reaction can occur spontaneously.

Positive

If ∆G is positive, the reaction is non-spontaneous.

Less

A system with a higher Gibbs free energy is considered less stable.

More

A system with a lower Gibbs free energy is considered more stable.

RNA

ATP is an example of a nucleoside triphosphate.

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O

This is the overall chemical formula for aerobic cellular respiration.

Ribose; adenine

ATP has 3 phosphates covalently linked to a ribose sugar, which also connects to an adenine nitrogenous base.

Phosphoanhydride bonds

These are the bonds found between phosphate groups.

Unstable

ATP molecules are unstable because the three phosphate groups are all negatively charged and repel each other.

ATP

This is known as the cellular energy currency.

Hydrolysis reaction

ATP → ADP + Pi is an example of this type of reaction.

Spontaneous; exergonic

ATP hydrolysis reactions release free energy, making them spontaneous and exergonic.

Condensation reaction

ADP + Pi → ATP is an example of this type of reaction.

Non-spontaneous; endergonic

Condensation reactions absorb free energy, making them non-spontaneous and endergonic.

Phosphate

ATP provides energy for all cells by transferring this from ATP to another molecule.

Reaction coupling

This links unfavorable reactions with favorable ones, as long as the net free energy change for the two reactions is negative.

Mitochondria

These organelles make many ATP molecules through cellular respiration.

Cytosol

The fluid component of the cytoplasm where various cellular processes occur.

Mitochondrial Membranes

Mitochondria possess two membranes: an outer membrane and an inner membrane.

Cristae

Infoldings of the inner mitochondrial membrane that increase the surface area for chemical reactions.

Intermembrane Space

The acidic region located between the outer and inner mitochondrial membranes.

Mitochondrial Matrix

The area inside the inner mitochondrial membrane, containing enzymes and mitochondrial DNA.

Red Blood Cells

Cells that transport oxygen but do not contain mitochondria to maximize oxygen carrying capacity.

DNA

The genetic material found in the mitochondrial matrix, distinct from nuclear DNA.

Ribosomes

Mitochondrial ribosomes are involved in protein synthesis within the mitochondria.

Endosymbiotic Theory

The hypothesis that explains the origin of mitochondria and chloroplasts from engulfed bacteria.

Aerobic Cellular Respiration

A catabolic pathway that requires oxygen to convert glucose into energy.

Glycolysis

The first step of aerobic cellular respiration that breaks down glucose into pyruvate.

Krebs Cycle

A series of reactions in aerobic respiration that generates electron carriers for the electron transport chain.

Oxidative Phosphorylation

The final stage of aerobic respiration where ATP is produced using energy from electrons.

Exergonic

A term describing reactions that release energy, such as aerobic cellular respiration.

Oxidative

Referring to reactions that involve the loss of electrons, characteristic of aerobic cellular respiration.

Fermentation

An anaerobic process that allows glycolysis to continue in the absence of oxygen.

Location of Glycolysis

Glycolysis occurs in the cytosol of the cell.

Coenzyme

An organic non-protein molecule that assists enzymes in catalyzing reactions.

Reduce

To gain electrons or hydrogen atoms, often resulting in the conversion of a molecule.

Electron Transport Chain (ETC)

A series of protein complexes located in the inner mitochondrial membrane that transfer electrons and generate ATP.

Energy Investment Phase

The initial phase of glycolysis where ATP is consumed to phosphorylate glucose and its derivatives.

Energy Payoff Phase

The phase of glycolysis where ATP and NADH are produced.

Glucose-6-Phosphate

A phosphorylated form of glucose that is trapped in the cell and serves as an intermediate in glycolysis.

Fructose-6-Phosphate

An isomer of glucose-6-phosphate that is formed during glycolysis.

Phosphofructokinase

An important regulatory enzyme in glycolysis that catalyzes the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate.

G3P

Glyceraldehyde-3-phosphate, a three-carbon sugar produced during glycolysis.

Substrate-Level Phosphorylation

A process of generating ATP by directly transferring a phosphate group to ADP from a phosphorylated intermediate.

Kinase

An enzyme that catalyzes the transfer of a phosphate group from ATP to a substrate.

Net Products of Glycolysis

The total yield of glycolysis from one glucose molecule, which includes 2 ATP, 2 NADH, and 2 pyruvate.

Pyruvate Manipulation Reactions

A series of reactions that convert pyruvate into acetyl-CoA, linking glycolysis to the Krebs cycle.

Decarboxylation

The removal of a carbon atom from a molecule, releasing it as carbon dioxide.

Acetyl Group

A two-carbon molecule that is formed from the oxidation of pyruvate and is used in the Krebs cycle.

NAD+

An electron carrier molecule that is reduced to NADH during glycolysis and the Krebs cycle.

Acetyl-CoA

The product formed when an acetyl group binds to coenzyme A, serving as a substrate for the Krebs cycle.

Intermediates

Compounds that form during the steps of a metabolic pathway, such as the Krebs cycle.

Oxaloacetate

A four-carbon molecule that combines with acetyl-CoA to initiate the Krebs cycle.

Citrate

The six-carbon compound formed when oxaloacetate combines with acetyl-CoA.

2 Acetyl-CoA

The number of acetyl-CoA molecules oxidized by the Krebs cycle for every one glucose molecule.

2

The number of cycles of the Krebs cycle that occur per glucose molecule.

Net Production of 1 Krebs Cycle

The production of 2 CO2, 3 NADH, 1 FADH2, and 1 ATP.

Net Production of 2 Krebs Cycles

The production of 4 CO2, 6 NADH, 2 FADH2, and 2 ATP from one glucose molecule.

Waste Product of the Krebs Cycle

Carbon dioxide (CO₂) released as a byproduct of the cycle.

Chemiosmosis

The mechanism of ATP generation that occurs when energy is stored in the form of a H+ concentration gradient across a membrane.

Mitochondrial Inner Membrane

The location of the electron transport chain in eukaryotic cells.

Cell Membrane

The location of the electron transport chain in prokaryotic cells.

H+ Pumping

The process by which energy released from electrons is used to pump protons across a membrane.

Endergonic

The type of reaction that requires energy input, such as the pumping of H+ across the inner mitochondrial membrane.

ETC Proteins

Proteins in the electron transport chain that act as pumps to move protons across the membrane.

Electrochemical gradient

A difference in charge and concentration of ions across a membrane, created by the pumping of protons.

Coenzyme Q (CoQ)/ubiquinone

A hydrophobic molecule that serves as an electron carrier within the mitochondrial inner membrane.

Cytochrome c

A small, hydrophilic protein that transports electrons between complex III and complex IV in the electron transport chain.

NADH

A reduced form of nicotinamide adenine dinucleotide that donates electrons to the electron transport chain, resulting in more proton pumping than FADH2.

FADH2

A reduced form of flavin adenine dinucleotide that enters the electron transport chain at complex II and results in less proton pumping than NADH.

ATP synthase

An enzyme that synthesizes ATP from ADP and inorganic phosphate using the energy from protons flowing down their electrochemical gradient.

Electron acceptors

Molecules that receive electrons during cellular respiration or fermentation, differing between aerobic and anaerobic processes.

Alcohol fermentation

A type of fermentation that converts pyruvate into ethanol and carbon dioxide, primarily occurring in yeast and some bacteria.

Lactic acid fermentation

A type of fermentation that converts pyruvate into lactate, occurring in human muscle cells under anaerobic conditions.

Cori cycle

The metabolic pathway that recycles lactate produced in muscles back to glucose in the liver.

Final electron acceptor

The molecule that receives electrons at the end of the electron transport chain, which is oxygen in aerobic respiration.

NAD+ regeneration

A process that allows glycolysis to continue by replenishing the electron carrier necessary for ATP production.

Anaerobic processes

Metabolic pathways that occur without oxygen, such as glycolysis and fermentation.

Obligate aerobes

Organisms that require oxygen for survival and rely solely on aerobic respiration.

Obligate anaerobes

Organisms that cannot tolerate oxygen and exclusively use anaerobic respiration.

Facultative anaerobes

Organisms that can switch between aerobic respiration, anaerobic respiration, and fermentation depending on oxygen availability.

Microaerophiles

Organisms that require oxygen but at lower levels than are present in the atmosphere, as high concentrations can be harmful.

Aerotolerant

Organisms that do not use oxygen for growth but can survive in its presence.

Fuel sources priority

The order in which the body utilizes energy sources, with carbohydrates being the most preferred, followed by fats and then proteins.

Monosaccharides

Simple sugars that result from the hydrolysis of disaccharides and can be converted into glucose or glycolytic intermediates.

Gluconeogenesis

The metabolic pathway that generates glucose from non-carbohydrate substrates.