Energy and Metabolism

These flashcards cover key vocabulary terms and definitions related to energy and metabolism from the lecture notes.

Bioenergetics

The study of how energy moves and is used in living things.

• Includes Metabolism: all chemical reactions in a cell/organism.

• Involves Energy flow: energy transfer between organisms in an ecosystem.

• A specific application of Thermodynamics: study of energy changes in matter.

Photosynthesis

The process by which plants capture sunlight to make sugar (glucose) from CO₂ and H₂O.

• Also called Plant energy capture: plants use sunlight to convert CO₂ and H₂O into glucose.

• Chemical equation: CO₂ + H₂O → glucose.

• Creates Chemical energy: energy stored in chemical bonds, like glucose.

Metabolism

All the chemical reactions happening inside a cell or an organism.

• A core part of Bioenergetics: the study of energy in living things.

• Reactions often follow a Metabolic pathway: a series of steps converting a starting material to a product.

• Main types: aerobic (with oxygen) and anaerobic (without oxygen).

Metabolic pathway

A step-by-step series of chemical reactions that convert a starting material into a final product.

• Foundational to Metabolism: all chemical reactions in an organism.
• Starting material is a Substrate.
• Each step is a Chemical reaction.

Cellular respiration

The process of breaking down glucose to extract energy, producing CO₂ and H₂O.

• Chemical equation: glucose + O₂ → CO₂ + H₂O + energy.
• Often starts with Glycolysis: the first step in glucose breakdown, found in most organisms.
• Primarily Aerobic metabolism (requires oxygen, produces more energy) but can involve Anaerobic metabolism (without oxygen).

Redox reactions

Chemical reactions where electrons are transferred between molecules.

• An Oxidizing agent takes electrons from another molecule.
• A Reducing agent gives away electrons to another molecule.
• A molecule is Oxidized when it loses electrons and energy.
• A molecule is Reduced when it gains electrons and energy.
• Mnemonic: OIL RIG (Oxidation Is Loss, Reduction Is Gain of electrons).

Oxidizing agent

The molecule that takes electrons from another molecule.

• Causes another molecule to be Oxidized.
• Occurs in Redox reactions.

Reducing agent

The molecule that gives away electrons to another molecule.

• Causes another molecule to be Reduced.
• Occurs in Redox reactions.

Oxidized

When a molecule loses electrons and energy.

• From OIL RIG: Oxidation Is Loss.
• Occurs during Redox reactions when an Oxidizing agent takes electrons.

Reduced

When a molecule gains electrons and energy.

• From OIL RIG: Reduction Is Gain.
• Occurs during Redox reactions when a Reducing agent gives electrons.

OIL RIG

Mnemonic for Oxidation Is Loss, Reduction Is Gain (of electrons).

• 'Oxidation Is Loss' means a molecule is Oxidized.
• 'Reduction Is Gain' means a molecule is Reduced.
• Helps remember electron transfers in Redox reactions.

Glycolysis

The first step in breaking down glucose, found in almost every organism.

• Key initial step in Cellular respiration.
• Can be part of Anaerobic metabolism.
• Occurs in the Glycolysis location: the cytosol of cells.
• Its widespread presence suggests Common ancestry.

Anaerobic metabolism

Energy generation processes that occur without oxygen.

• One of the Metabolism types, unlike Aerobic metabolism which requires oxygen.
• Glycolysis can be an initial anaerobic process.

Aerobic metabolism

Energy generation processes that require oxygen and produce more energy.

• One of the Metabolism types, unlike Anaerobic metabolism.
• Primary mode for Cellular respiration.

Activation energy

The small amount of energy needed to initiate a chemical reaction.

• Essential for any Chemical reaction.
• Part of the initial input for an Endergonic reaction.

Exergonic reaction

A chemical reaction that releases energy and happens spontaneously.

• Can provide energy for an Endergonic reaction in Coupled reactions.
• A type of Chemical reaction.

Endergonic reaction

A chemical reaction that requires an initial input of energy.

• Can be powered by an Exergonic reaction through Coupled reactions.
• A type of Chemical reaction; requires Activation energy.

First Law of Thermodynamics

Energy cannot be created or destroyed, only transformed into different forms.

• Fundamental principle of Thermodynamics.
• Describes Energy transformation.

Second Law of Thermodynamics

Energy transfers are not 100% efficient; some energy is lost as heat.

• Fundamental principle of Thermodynamics.
• Lost energy increases Entropy.
• Lost energy is often Heat energy.
• Implies Energy efficiency is always <100%.

Entropy

The measure of disorder or randomness in a system.

• Increases with energy transfers, as per the Second Law of Thermodynamics (energy lost as heat).

Adenosine Triphosphate (ATP)

The main energy currency of the cell that powers biochemical reactions.

• The cell's Energy currency.
• Energy released by ATP Hydrolysis: breaks ATP into ADP and Pi.
• Forms ADP (Adenosine Diphosphate) and Pi (Inorganic Phosphate) after losing a phosphate.
• Energy stored in high-energy bonds (Energy storage in ATP).
• Cells perform ATP recharge: recombining ADP and Pi using energy from food.

ATP Hydrolysis

The reaction that breaks down ATP into ADP and inorganic phosphate, releasing energy.

• Breaks down Adenosine Triphosphate (ATP).
• Products are ADP and Pi.
• Energy comes from breaking high-energy bonds in ATP.
• This exergonic reaction powers cellular endergonic processes via Coupled reactions.

ADP (Adenosine Diphosphate)

What remains when ATP loses one phosphate molecule.

• Formed from ATP during ATP Hydrolysis.
• Combines with Pi during ATP recharge to form ATP.

Pi (Inorganic Phosphate)

A free phosphate group released during ATP hydrolysis.

• Produced from ATP breakdown during ATP Hydrolysis.
• Combines with ADP during ATP recharge to form ATP.

Coupled reactions

Reactions in which one exergonic reaction provides the energy for an endergonic reaction.

• An Exergonic reaction fuels an Endergonic reaction.
• Example: ATP Hydrolysis powers many cellular endergonic processes.

Reversible reaction

A reaction in which products can be reverted back to reactants.

• A type of Chemical reaction.

Thermodynamics

The study of how energy moves and changes in matter.

• Governed by the First and Second Laws of Thermodynamics.
• Bioenergetics applies thermodynamics to living systems.
• Includes concepts like Energy transformation and Heat energy.

ΔG (Gibbs Free Energy)

A measure of the energy available for work in a reaction.

• Negative ΔG: Exergonic reaction (releases energy, spontaneous).
• Positive ΔG: Endergonic reaction (requires energy input).

Enzyme specialization

The process by which enzymes evolve to function optimally in their specific environments.

• Enzymes facilitate steps in a Metabolic pathway.
• Catalyze specific Chemical reactions.

Chemical reaction

A process that leads to the transformation of one set of chemical substances to another.

• Occur in Metabolic pathways.
• Need Activation energy to start.
• Can be Exergonic or Endergonic.
• Some are Reversible reactions.
• Starting materials are Substrates.

Substrate

The starting material that undergoes a chemical reaction in a metabolic pathway.

• Transformed by a Chemical reaction as part of a Metabolic pathway.

Energy flow

The transfer of energy from one organism to another in an ecosystem.

• Driven by organisms like Herbivores, Carnivores, and Decomposers.
• Central concept in Bioenergetics.

Herbivores

Organisms that eat plants to obtain energy.

• Part of Energy flow; eaten by Carnivores.

Carnivores

Organisms that eat herbivores or other animals for energy.

• Part of Energy flow; consume Herbivores.

Decomposers

Organisms that break down dead matter, recycling nutrients back into the environment.

• Crucial for Energy flow by recycling nutrients.

Plant energy capture

The process of plants using sunlight to convert carbon dioxide and water into glucose.

• Same as Photosynthesis.
• Photosynthetic equation: CO₂ + H₂O → glucose.
• Stores Chemical energy.

Photosynthetic equation

The chemical equation representing the process of photosynthesis: CO₂ + H₂O → glucose.

• Describes Photosynthesis (Plant energy capture).

Cellular respiration equation

The chemical equation representing cellular respiration: glucose + O₂ → CO₂ + H₂O + energy.

• Describes Cellular respiration.

Common ancestry

The idea that various organisms share similar metabolic pathways indicating a shared evolutionary history.

• Example: Glycolysis, found in most organisms, suggests ancient origin.

Energy storage in ATP

The high-energy bonds between phosphate groups in ATP that store energy for cellular processes.

• Refers to Adenosine Triphosphate (ATP).
• Energy released when these bonds break during ATP Hydrolysis.
• Stored energy is a form of Chemical energy.

Glycolysis location

A metabolic pathway present in the cytosol of cells for glucose breakdown.

• Cellular location of Glycolysis.

Energy transformation

The conversion of energy from one form to another without loss.

• Central to the First Law of Thermodynamics.
• Converts between forms like Chemical energy and Kinetic energy.
• The Second Law of Thermodynamics notes some energy is always lost as Heat energy.

Chemical energy

The energy stored in the chemical bonds of molecules.

• Produced by Photosynthesis (Plant energy capture) as glucose.
• Stored in ATP (Energy storage in ATP).
• Can be transformed into Kinetic energy.

Kinetic energy

The energy of motion that can be converted from stored chemical energy.

• A result of Energy transformation from sources like Chemical energy.

Heat energy

The energy transferred between systems or objects with different temperatures.

• Lost during energy transfers as per the Second Law of Thermodynamics; increases Entropy.
• Often a byproduct of Energy transformation.

ATP recharge

The process by which ADP and Pi are recombined to form ATP using energy from food.

• Regenerates Adenosine Triphosphate (ATP).
• Combines ADP and Pi to rebuild high-energy bonds (Energy storage in ATP).
• Energy comes from catabolic processes like Cellular respiration.

Energy efficiency

The ratio of useful energy output to total energy input in a system.

• Always less than 100% due to the Second Law of Thermodynamics (some energy lost as heat).

Metabolism types

The two main types of metabolism: aerobic (with oxygen) and anaerobic (without oxygen).

• Subcategories of Metabolism.
• Aerobic: requires oxygen, more energy.
• Anaerobic: without oxygen.

Energy currency

The term for molecules like ATP that serve as carriers of energy in biological systems.

• Primary example: Adenosine Triphosphate (ATP).