AP Bio Unit 3 Terms

First Law of Thermodynamics

Energy cannot be created or destroyed, only transformed

Free Energy

The energy available in a system to do work (like metabolic processes)

Endergonic

Free energy is absorbed/needed during a process, reaction occurs non spontaneously 

Exergonic

Free energy is released during a process, reaction occurs spontaneously 

Energy Coupling

Use of an exergonic process to drive an endergonic one

Enzymes

Proteins that are biological catalysts, speeding up chemical reactions in cells

Catalysis

Process of speeding up a chemical reaction using an enzyme 

Catabolism

Breaking down a larger complex molecule into smaller products

Anabolism

Building a larger complex molecule using smaller reactants

Substrates 

The substance upon which an enzyme acts, usually a small molecule 

Koshland’s Induced Fit model

The model suggests that enzymes are flexible structures, binding of the substrate results in changes to shape with the active site

Fisher’s Lock and Key model 

Enzymatic action requires the enzyme and substrate to fit like a lock and key to have a chemical effect on each other. 

Competitive Inhibitor

Non-acting molecule that competes with the substrate to bind to the active site, blocks catalysis.

Non-competitive inhibitor/Allosteric Inhibitor

Non-acting molecule that binds to the allosteric site of a protein, causes conformational change so that the substrate cannot bind to the active site.

Conformational Change

Change that induces change in 3D shape 

Activation Energy

The initial investment of energy for a starting reaction in order to break bonds 

Allosteric Activator 

Modify active site so that substrate can now fit into the protein, activates the enzyme to be able to fit onto substrate. 

Enzyme cooperativity

Binding of one substrate to the active site increases affinity for other substrates to bind to the active sites (in quaternary/tertiary proteins).

Allosteric Feedback Inhibition

The end product of a feedback loop acts as an allosteric inhibitor, such that if there is too high concentration of the product, there will be more inhibition of the first enzyme so that the loop stops producing the product.

Kinetic Energy 

The energy an object/particle possesses because of its motion. Faster it moves, more KE. 

Thermal Energy

KE of atoms/particles hitting each other, transfer called heat.

Potential Energy

Possession of energy (in atoms) due to the arrangement of their bonds and electrons

Chemical Enerfy

Potential energy available for release in a chemical reaction. 

1st Law of Thermodynamics

Conservation of Energy, energy cannot be created nor destroyed, only transformed.

2nd Law of Thermodynamics

Every energy transfer increases Universe Entropy 

Universe Entropy

Measure of the universe’s disorder, all the ways energy can be arranged. Can only increase.

Spontaneous reaction

Energetically favorable, contributes to universe entropy

Non-Spontaneous

Energetically unfavorable, requires energy input and will not occur naturally. 

Saturation Point

Point where all active sites on enzymes are saturated with substrate, and the reaction rate plateaus.