AP BIO Energy/enzymes and Photosynthesis

Thermal Energy

The sum of chemical energy in molecular bonds and kinetic energy from molecular movement.

Temperature

The average kinetic energy of molecules.

Heat

The flow of kinetic energy between objects or places.

Metabolism

All of the biological chemical reactions.

Metabolic Pathway

A series of chemical reactions resulting in a product, each step facilitated by a different enzyme.

Catabolism

Metabolic pathways that release energy by breaking down molecules.

Anabolism

Metabolic pathways that use energy to synthesize complex molecules.

Entropy

A measure of disorder or randomness in a system.

The First Law of Thermodynamics

Energy can be converted from one form to another but cannot be created or destroyed.

The Second Law of Thermodynamics

All systems tend toward increased entropy; energy transformation results in loss of usable energy as heat.

Spontaneous Process

A process that occurs naturally without external energy input, typically increasing disorder.

Exergonic Pathway

A chemical reaction with a negative change in Gibbs Free Energy, increasing entropy and happening spontaneously.

Endergonic Pathway

A chemical reaction with a positive change in Gibbs Free Energy, decreasing entropy and requiring energy input.

Energy Coupling

The use of energy from exergonic reactions to drive endergonic reactions, typically mediated by ATP.

Adenosine Triphosphate (ATP)

A nucleoside composed of ribose, adenine, and three phosphates, releasing energy upon hydrolysis.

Substrate Level Phosphorylation

An enzymatic transfer of a phosphate from ATP to a molecule, forming a high-energy phosphorylated intermediate.

Enzyme

A protein serving as a biological catalyst, speeding up reactions by lowering activation energy.

Activation Energy

The initial energy input needed to start a chemical reaction.

Substrate

The reactant that an enzyme binds to.

Active Site

The specific region on an enzyme where a substrate binds.

Induced Fit

The alteration of substrate or active site to form a more precise fit.

Competitive Inhibitor

Molecules similar in structure to the substrate that bind to an enzyme's active site, blocking substrate access.

Allosteric Site

A site on an enzyme distinct from the active site where regulatory molecules can bind.

Allosteric Regulation

Regulation of enzyme activity through molecules binding to allosteric sites.

Activator

A molecule that increases enzyme activity by stabilizing its active form.

Inhibitor

A molecule that decreases enzyme activity by stabilizing its inactive form.

Feedback Inhibition

An allosteric regulation mechanism where the end product inhibits the first enzyme in a metabolic pathway.

Cofactor

A non-protein molecule or atom required for an enzyme's proper function.

Coenzyme

An organic cofactor, often vitamins or their derivatives.

Denatured Enzyme

An enzyme that has lost its three-dimensional shape, often irreversibly.

Photoautotroph

An organism that uses photosynthesis to produce its own food.

Photosynthesis

The process of capturing solar energy and converting it to chemical energy in the form of sugars.

Chlorophyll

The green pigment crucial for photosynthesis that absorbs light energy.

Photosystem

A cluster of pigment molecules where energy transfer occurs during photosynthesis.

Electron Transport Chain

A series of proteins in a membrane that transfer electrons and progressively create a proton gradient.

Electrochemical Gradient

A difference in concentration and electric charge across a membrane that stores potential energy.

ATPase

An enzyme that synthesizes ATP by capturing kinetic energy from H+ flow.

Proton Pump

A protein that uses energy to transport protons (H+ ions) across a membrane.

NADPH

An electron carrier that transfers energized electrons to power the Calvin Cycle.

Light Dependent Reactions

The stage of photosynthesis where light energy is absorbed and converted into chemical energy.

Light Independent Reactions (Calvin Cycle)

The stage of photosynthesis utilizing energy from light dependent reactions to produce glucose.

Carbon Fixation

The initial step of the Calvin Cycle where CO2 is attached to an organic molecule.

Rubisco

An enzyme that catalyzes the attachment of CO2 to RuBP in the Calvin Cycle.

Stroma

The fluid inside chloroplasts where the Calvin Cycle occurs.

Thylakoid

Membrane-bound compartments in chloroplasts where light dependent reactions happen.

Cyanobacteria

Photosynthetic bacteria with structures for oxygenic photosynthesis.