AP Bio unit 3

Energy

Energy

The ability to do work; necessary for all life processes

Metabolism

All chemical reactions in organisms, including energy use

Catabolic Pathways

Break down molecules and release energy (ex: cellular respiration)

Anabolic Pathways

Build complex molecules and require energy (ex: photosynthesis)

First Law of Thermodynamics

Energy can't be created or destroyed, only transformed

Second Law of Thermodynamics

Every energy transfer increases the universe's entropy (disorder)

Kinetic Energy

Energy of motion, ex: heat

Potential Energy

Stored energy, ex: in chemical bonds

Exergonic Reaction

Releases energy, spontaneous (ex: cellular respiration)

Endergonic Reaction

Absorbs energy, non-spontaneous (ex: photosynthesis)

ATP

The main energy currency of cells; powers cellular processes

Hydrolysis of ATP

Breakdown of ATP to ADP, releases energy

Enzymes

Proteins that speed up reactions by lowering activation energy

Active Site

Where a substrate binds on an enzyme

Competitive Inhibition

Inhibitor competes with substrate for the enzyme's active site

Noncompetitive Inhibition

Inhibitor binds elsewhere, changing enzyme shape and function

Glycolysis

Breaks down glucose into pyruvate, occurs in cytoplasm, produces 2 ATP

Fermentation

Anaerobic process, regenerates NAD+, produces lactate or ethanol

Citric Acid Cycle

Completes glucose oxidation, produces NADH, FADH₂, and CO₂

Electron Transport Chain (ETC)

Series of proteins that transport electrons, creating ATP

Chemiosmosis

Process that uses proton gradient to produce ATP

Photosynthesis

Process where plants convert light energy into glucose

Light-dependent Reactions

First stage of photosynthesis, produces ATP and NADPH

Calvin Cycle

Second stage of photosynthesis, uses ATP and NADPH to produce glucose