Metabolism and Enzyme Regulation Overview

Metabolism

all of the chemical reactions in an organism

Metabolic pathways

series of chemical reactions that either build complex molecules or break down complex molecules

Catabolic Pathways

Pathways that release energy by breaking down complex molecules into simpler compounds

Anabolic Pathways

Pathways that consume energy to build complicated molecules from simpler compounds

Energy

the ability to do work

Kinetic energy

energy associated with motion

Thermal energy

energy associated with the movement of atoms or molecules

Potential energy

stored energy

Chemical energy

potential energy available for release in a chemical reaction

1st Law of Thermodynamics

Energy cannot be created or destroyed; Energy can be transferred or transformed

2nd Law of Thermodynamics

Energy transformation increases the entropy (disorder) of the universe

Free Energy

concept used to determine the likelihood of reactions in organisms, or if the reactions are energetically favorable

ΔG = ΔH - TΔS

Formula used to calculate free energy change

Exergonic reactions

reactions that release energy

Endergonic reactions

reactions that absorb energy

ATP

Adenosine triphosphate: molecule that organisms use as a source of energy to perform work

Phosphorylation

the released phosphate moves to another molecule to give energy

Enzymes

macromolecules that catalyze (speed up) reactions by lowering the activation energy

Induced Fit

enzymes will change the shape of their active site to allow the substrate to bind better

Cofactors

non protein molecules that assist enzyme function

Enzyme inhibitors

reduce the activity of specific enzymes

Competitive inhibitors

reduce enzyme activity by blocking substrates from binding to the active site

Noncompetitive inhibitors

bind to an area other than the active site, which changes the shape of the active site preventing substrates from binding

Allosteric Regulation

molecules bind to an allosteric site which changes the shape and function of the active site

Allosteric activator

substrate binds to allosteric site and stabilizes the shape of the enzyme so that the active sites remain open

Allosteric inhibitor

substrate binds to allosteric site and stabilizes the enzyme shape so that the active sites are closed (inactive form)

Cooperativity

substrate binds to one active site which stabilizes the active form

Feedback Inhibition

the end product of a metabolic pathway can act as an inhibitor to an early enzyme in the same pathway