AP Bio: unit 3 - cell energetics

metabolism

the totality of an organism's chemical reactions, managing the material and energy resources of a cell

catabolic pathway

a metabolic process that breaks down complex molecules (such as glucose or fats) into simpler ones, releasing stored chemical energy in the process

anabolic pathway

a metabolic route that consumes energy (usually ATP) to build complex molecules from simpler ones, essential for biosynthesis, growth, and repair

exergonic reactions

a spontaneous chemical process that releases free energy, characterized by a negative change in Gibbs free energy

endergonic reactions

non-spontaneous chemical processes that absorb energy from their surroundings, resulting in products with higher potential energy than the reactants

cell does 3 kinds of work

mechanical, transport, chemical

ATP (adenosine triphosphate)

adenine + ribose sugar + 3 phosphate groups

ATP hydrolysis

ATP + H2O → ADP + Pi + energy

activation energy

the minimum initial energy required to break chemical bonds and start a chemical reaction

ADP (adenosine diphosphate)

adenine + ribose sugar + 2 phosphate groups

enzyme

specialized biological catalysts, typically proteins (or sometimes RNA), that speed up metabolic reactions by lowering the activation energy without being consumed in the process

catalyst

increases the rate of a chemical reaction by lowering the activation energy required, without being consumed or permanently altered in the process

substrates

the specific reactant molecule upon which an enzyme acts

active site

a specific, 3D region of an enzyme (usually a pocket or cleft) where substrate molecules bind, interact, and undergo a chemical reaction to become products

induced fit

a model of enzyme-substrate interaction where the enzyme's active site changes shape slightly upon substrate binding to achieve a tighter, more precise "handshake" fit

enzyme denaturation

caused by extreme temperatures or pH, renders the active site incapable of binding to its substrate

enzyme mutation

a permanent, random change in the DNA sequence (e.g., substitution, deletion, insertion) that alters the amino acid sequence, disrupting the protein's primary structure

cofactors

non-protein chemical compounds or metallic ions required for an enzyme to become catalytically active

coenzyme

a non-protein, organic molecule (often vitamin-derived) that binds loosely to an enzyme to assist in catalyzing biochemical reactions

competitive inhibitor

a molecule that reduces enzyme activity by binding directly to the active site, physically blocking the substrate from entering

noncompetitive inhibitor

a molecule that binds to an enzyme at an allosteric site (a location other than the active site)

allosteric regulation of enzymes

the modulation of enzyme activity (activation or inhibition) by the binding of an effector molecule at a site other than the active site