Cellular respirations • Oxygen atoms, being highly electronegative, pull shared electron pairs toward themselves when bound to carbon. • This electron movement is equivalent to carbon losing electrons. • The attachment of oxygen to carbon places electrons in a more stable configuration, releasing free energy. • Free Energy and Reaction: • Aerobic oxidation of glucose moves valence electrons from high free energy (glucose) to lower free energy (carbon dioxide and water). • Results in: • Decrease in potential energy. • Increase in entropy. • Reaction:  • Standard free energy change (): -2870 kJ/mol glucose under standard lab conditions (25°C, 101.3 kPa). • Cellular conditions yield : ~-3012 kJ/mol glucose. • Standard value of -2870 kJ/mol glucose is used for calculations. • Energy Release: • Burning glucose in a test tube releases energy as heat and light. • In cells: • About 34% of free energy is captured in molecules like ATP. • These molecules serve as energy sources for powering endergonic processes. This breakdown summarizes key points for understanding the aerobic oxidation of glucose and its biological significance.

Activation Energy

The minimum energy required to initiate a chemical reaction.

Glucose Combustion

The process through which glucose reacts with oxygen, producing energy, carbon dioxide, and water.

Stable Covalent Compounds

Molecules that have strong bonds requiring significant energy to break.

Enzymes

Proteins that act as catalysts to speed up chemical reactions by lowering activation energy.

Cellular Respiration

The metabolic process that converts biochemical energy from nutrients into ATP.

Aerobic Respiration

A form of cellular respiration that requires oxygen to produce energy.

Electron Acceptors

Molecules that receive electrons during a redox reaction.

Obligate Aerobes

Organisms that require oxygen to survive.

Obligate Anaerobes

Organisms that cannot survive in the presence of oxygen.

Facultative Anaerobes

Organisms that can switch between aerobic and anaerobic respiration.

Substrate-Level Phosphorylation

A method of ATP production that occurs when a phosphate group is directly transferred to ADP.

Oxidative Phosphorylation

The process of ATP production that occurs via redox reactions in the electron transport chain.

Nicotinamide Adenine Dinucleotide (NAD⁺)

A coenzyme that carries electrons to the electron transport chain.

Hydrogen-Ion Gradient

A difference in hydrogen ion concentration across a membrane, used to generate ATP.

Chemoautotrophs

Organisms that obtain energy by oxidizing inorganic compounds.

Photoautotrophs

Organisms that use light energy to synthesize organic compounds from inorganic substances.

Heterotrophs

Organisms that depend on other organisms for food and energy.

Redox Reactions

Chemical reactions involving the transfer of electrons, resulting in oxidation and reduction.

Exergonic Reaction

A chemical reaction that releases energy.

Free Energy

The amount of energy available to do work in a biological system.

Activation Energy Barrier

The energy threshold that must be overcome to initiate a reaction.

ATP (Adenosine Triphosphate)

The primary energy carrier in cellular metabolism.

ADP (Adenosine Diphosphate)

The product formed when ATP loses a phosphate group; can be converted back to ATP.

Krebs Cycle

A series of enzyme-catalyzed chemical reactions used by aerobic organisms to generate energy.

Electron Transport Chain

A series of complexes located in the mitochondrial membrane that perform oxidative phosphorylation.

Oxygen's Role in Respiration

Functions as the final electron acceptor during aerobic respiration.

Chemical Potential Energy

The energy stored in the chemical bonds of a substance.

Fermentation

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

Glycolysis

The metabolic pathway that converts glucose into pyruvate, producing a small amount of ATP.

Carbon Dioxide,

The waste product of aerobic respiration after glucose is oxidized.

Water

The product formed when oxygen is reduced during cellular respiration.

Mitochondrial Inner Membrane

The site of the electron transport chain where ATP is generated.

Clostridium tetani

A bacterium that causes tetanus and is an obligate anaerobe.

Escherichia coli

A facultative anaerobe commonly found in the intestines of humans and animals.

Vibrio cholerae

A facultative anaerobe responsible for cholera.

Salmonella enteritidis

A facultative anaerobe that causes food poisoning.

Chemical Reactions of Cellular Respiration

Enzyme-catalyzed redox reactions that convert glucose and oxygen into energy.

Thermodynamics

The branch of physics that deals with heat and temperature and their relation to energy and work.

Metabolic Rate

The rate at which organisms convert energy from nutrients into cellular energy.

Growth and Metabolic Activity

The relationship between the growth rate of organisms and their energy consumption.

Experimental Investigation

Controlled experiments designed to test hypotheses in biological studies.

Hydrocarbons

Organic compounds made solely of hydrogen and carbon; combustion releases energy.

Energy Transfer

The movement of energy from one form to another, for example from chemical potential energy to ATP.

NADH

The reduced form of NAD⁺, which carries electrons to the electron transport chain.

Phosphoenolpyruvate (PEP)

A key intermediate in glycolysis that donates a phosphate to ADP to form ATP.