Energy & ATP Vocab: ATP Objectives: 1.Describe the structure of ATP and how it stores energy. 2.Give examples of work that cells perform. 3.Summarize the ATP cycle.

Life depends on the fact that energy can be converted from one form to another.

Energy Energy: the capacity to rearrange matter/ “do work” There are two basic forms of energy: –Kinetic energy- energy of motion; moving objects do work by transferring motion to other matter Examples: Motion of one car causes motion of others in a crash. Includes: heat (random motion of molecules) & light –Potential energy- stored energy as a result of location or structure (energy in arrangement of atoms in a molecule) Includes: Chemical energy- energy available to cell to do work

Energy Transformations Thermodynamics- study of energy transformation that occur in a system (collection of matter)

Endergonic v. Exergonic Rxns Release Energy Energy in Bonds of reactants > Bonds of products Ex.: Combustion; Respiration Energy Required/Absorbed Energy in Bonds of Product > Bonds of Reactants Ex.: Photosynthesis; Biosynthesis

Reactants Potential energy of molecules Energy required Products Amount of energy required Endergonic reaction, energy is absorbed from surroundings. Products contain more energy in bonds than reactants. Examples of endergonic reactions?

Reactants Amount of energy released Potential energy of molecules Energy released Products Exergonic reaction, energy is released. Bonds of reactants contain more energy than those in the products. Examples of exergonic reactions?

Endo or Exergonic Reaction? 1.Use of gasoline in a lawn mower 2.Photosynthesis 3.Synthesis of a protein in a cell 4.Synthesis of glycogen in a cell 5.Cell Respiration 6.Hydrolysis of ATP

Metabolism Sum of all reactions in an organisms Metabolic Pathway: Series of chem. Rxns that builds or breaks down complex molecules. Ex: Respiration; series of rxns that breaks down glucose and slowly releases energy stored in sugar.

Coupled Reactions Use of energy released in exergonic to drive endergonic reactions

Coupled Reactions

ATP Cells do NOT get energy directly from foods; Chemical energy stored in food must first be converted to energy stored in ATP. ADENOSINE TRIPHOSPHATE Adenosine: nitrogen- containing compound called ADENINE + 5 carbon sugar called RIBOSE Tail: 3 phosphate groups; SOURCE OF CELLULAR ENERGY.

ATP to ADP releases Energy ATP --> ADP + P+ ENERGY More energyLess energy (Remember: Energy cannot be gained or lost) Phosphate groups are negatively charged & REPEL one another – This makes ATP unstable. More Phosphate groups = more potential energy (trying to get away fr. One another). Energy is released when ATP --> ADP + P ADP: Adenosine Diphosphate (2 phosphates)

ATP Cycle ATP ADP + P+ ENERGY More energyLess energy

Cellular Respiration

ATP and Cellular Work ATP --> ADP + P + Energy Enzymes transfer the “P” to other molecules = PHOSPHOROLATION = Phosphate forms a bond with something else (something more stable; energy released) Energy released used to MAKE THINGS HAPPEN” = “work”

Enzymes Lower activation energy for reactions to proceed.

Reaction without enzyme E A with enzyme Energy Reactants Reaction with enzyme E A without enzyme Net change in energy (the same) Products Progress of the reaction Figure 5.14 The effect of an enzyme is to lower E A

a. b. c. d. e. f. Enzyme (sucrase) Active site Substrate(sucrose) Induced Fit Products released Substrate hydrolyzed Catalytic cycle of an enzyme:

Why don’t macromolecules such as DNA, carbohydrates, lipids spontaneously break down into simpler less energetic molecules? Energy barrier must be overcome, bonds between atoms must be weakened Referred to as energy of activation (E A ) How can this be accomplished? 1. add heat- problem? 2. enzyme- proteins that function as biological catalyst, lowers E A and are not consumed in reaction