Chapter 6

The Controlled Storage and Release of Energy

I. Energy

A. Potential Energy: Ability to do Work 1. Chemical Energy: Potential Energy Stored in Chemical Bonds. What is a Calorie?

B. Kinetic Energy: Energy of Motion

C. Thermal Energy: Release of Heat

I. Energy

D. First Law of Thermodynamics: The Total Energy in the Universe Remains Constant.

• Energy is NEVER destroyed or lost.• Energy is just converted.

I. Energy

E. Second Law of Thermodynamics: The Amount of Disorder, or Entropy, in the Universe is Increasing.• Energy flows from ordered forms to

disordered forms.• Heat is highly disordered energy.

II. Energy Conversions

What I Hope You Recall from Chemistry:

Reactants enter a reaction.Products are the end result of a reaction.Activation Energy is required to start or

activate all reactions.

II. Energy Conversions

A. Exergonic Reaction: Energy is Released. Energy Exits. (e.g. Catabolism: Break down of

molecules in digestion.)B. Endergonic Reaction: Energy is Stored in

Products. Energy Enters. (e.g. Anabolism: Energy is Stored in

biomass of muscle.)

Endergonic or Exergonic?

Anabolism.Catabolism.Metabolism.Burning wood.Merissa putting on her ‘Freshman 15.’Gasoline in your car.Sitting in this classroom.A tree growing.

III. ATP and Electron Transfers

A. ATP: Adenosine Triphosphate Gasoline: Cars ATP: Life

P P P

III. ATP and Electron Transfers

A. ATP: Adenosine Triphosphate Gasoline: Cars ATP: Life

adenine

riboseP P P

AMP

ADP

ATP

Fig. 6.8c, p. 100

III. ATP and Electron Transfers

B. Moving Electrons Can Do Work. The three phosphate groups of ATP share electrons.

C. ATP becomes ADP when one Phosphate is removed. Complete:

III. ATP and Electron Transfers

D. Phosphorylation: Transfer of a phosphate group.

E. Oxidation-Reduction Reaction: Transfer of Electrons.

1. Reduction: The unit that accepts electron is ‘reduced’ in charge. 2. Oxidation: The unit that donates electron is often oxygen.

IV. Enzymes

A. Enzyme: Organic molecule (almost always protein) that catalyzes a reaction.

* Catalyst: Molecule that speeds up a reaction but isn’t used up in the process.

IV. EnzymesB. Four Features of Enzymes: 1. Enzymes speed up reactions but they never make an impossible reaction possible. 2. Enzymes are not used up in the process of the reaction. 3. The same enzyme usually works for the forward and reverse reaction. 4. In general, enzymes are specific in regards to the substrates with which they interact.

IV. Enzyme

C. Enzyme Vocabulary Substrate: What is reacting Active Site: When Enzyme and Substrate Interact. Transition State: Temporary interaction between enzyme and substrate.

Fig. 6.16b, p. 105

two substrate molecules

active sight

substratescontactingactive siteof enzyme

TRANSITIONSTATE(tightestbinding butleast stable

endproduct

enzymeunchangedby thereaction

IV. Enzymes

D. Lock – n – Key Model (oversimplied): The substrate and enzyme fit perfectly.

E. Induced Fit Model (most accurate): The enzyme has ‘flex’ to allow it to rearrange bonds within the substate(s).

V. Regulation of Enzyme Activity

A. Environment: pH, Temperature

Effects of pH or Temp?

V. Enzymes

B. Allosteric Regulation: Another molecules changes the shape of the enzyme by docking at a location other than active site.

C. Coenzymes: Assist enzymes by speeding

electron or hydrogen transfer.