Bio ch. 6

An Introduction to Metabolism

Metabolism

maintenance system run by energy transfers, anabolism and catabolism

Metabolism (pic)

Kinetic energy

energy in motion

Thermal energy 

kinetic energy associated with random movement of atoms or molecules

Heat

thermal energy in transfer from one object to another

Potential energy

energy that matter possesses because of its location or structure

Chemical energy

potential energy available for release in a chemical reaction

1st Law of Thermodynamics

Energy cannot be created or destroyed, only transformed or transferred

2nd Law of Thermodynamics

The total energy in the universe remains constant, but the amount of HIGH QUALITY energy decreases and LOW QUALITY increases

Entropy 

degree of disorder

Free-energy

The porton of a system’s energy that can perform work

Chemical Equilibrium

G is at its lowest possible value in that system; a system at equilibrium cannot spontaneously change, so it can do no work

Exergonic reaction 

energy exits, G decreases, spontaneous, cellular respiration (Delta G = -686 kcal/mol)

Exergonic reaction (pic)

Endergonic reaction

absorbs free energy, energy enters (non-spontaneous), G increases, photosynthesis (686 kcal/mol)

Endergonic reaction (pic)

ATP

powers cellular work by coupling exergonic reactions with endergonic reactions

ATP (types of work)

chemical work: pushing of endergonic reactions that would not happen spontaneously; transport work: pumping of substances against concentration gradient; mechanical work: movement

Enzymes (identity)

proteins, act as catalyst (speed up reactions), lower amount of activation energy required, cannot change Delta G, cannot make endergonic exergonic

Enzyme (pic)

Enzyme binding (pic)

Enzymes (functioning)

If an enzyme becomes saturated with substrate, then add more substrate; all enzymes have optimal pH and temp. 

Cofactors

non-protein enzyme helpers

Coenzyme

Organic cofactor

Types of Enzyme Inhibition

Competitive, non-competitive, feedback

Enzyme Inhibition

can be helpful or harmful, covalent bond=permanent or hydrogen bond=temporary

Competitive Inhibition

resembles substrate and competes with substrate for active site; if inhibitor binds, substrate cannot; slows the rate of reaction

Non-competitive Inhibition

inhibitor binds to allosteric site and makes active site change shape; covalent bond=enzyme is “dead”, hydrogen bond=inhibitor is “switch”

Feedback Inhibition

metabolic pathways, final product of pathway is allosteric inhibitor for first enzyme in pathway, hydrogen bond

Feedback Inhibition (pic)

competitive inhibition

non-competitive inhibition (pic)