What is Energy?  Kinetic energy- energy of motion or energy that is presently doing work  The capacity to do work Two states of energy Ex. An arrow shot from a bow

 Potential energy- stored energy that has the potential to do work but is not in active use.

How is energy stored biologically?  Energy is stored in chemical bonds

Thermodynamics- the study of energy energy can neither be created or destroyed only transformed to a different form Laws of Thermodynamics 1st law Ex. plants convert light energy into chemical energy during photosynthesis 2nd law some useful energy is lost as heat when energy is transformed Ex. As we convert potential energy from food into kinetic energy as we work we lose some energy as heat

Producers 1st consumers 2nd consumers 3rd consumers 4th consumers Decomposers Inorganic nutrients

How much energy is passed on from one level to the next? 10% rule - only 10% of the energy is passed on from one level to the next the rest is lost as heat. 10% Since energy is constantly being transformed, as demonstrated by the food chain, then entropy is always increasing. Entropy- is a measure of disorder and represents the amount of unusable energy. Heat is disorganized energy that is unusable (like the heat that escapes your oven when you are cooking)

Free energy - useable energy that can do work. * The energy that a cell requires for immediate use is stored in ATP (adenosine triphosphate) - the cell’s energy currency - free energy is released when 1 of the P bonds are broken

There are 2 basic types of reactions Ex. ATP + H 2 O > ADP + P + free energy 1. Exergonic - reactions that release energy (the reactants possess more energy than the products). Ex. Glucose + O 2 > CO 2 + H 2 O + ATP

Ex. ADP + P + free energy > ATP + H 2 O 2. Endergonic - reactions that require the input of energy (the reactants possess less energy than the products). Ex. CO 2 + H 2 O + light energy > Glucose + O 2

Coupled reactions- an exergonic reaction provides energy to drive an endergonic reaction

Metabolism - all chemical and energy transformations that occur in cells as they use energy. (The sum of all chemical reactions w/in a cell). Anabolism- Small sub-unit molecules are bonded together to form larger complex molecules. (G+G+G+G+G+etc... = Starch) Catabolism- Larger complex molecules are broken down into smaller molecules. (Starch+ H 2 O = G+G+G+G+G+etc... )

Chemical reactions are regulated by Enzymes! Without enzymes, most biochemical reactions would not take place fast enough to sustain life. Why? Most chemical reactions require some input of energy to get started. Activation energy- the amount of input energy required to start a reaction.

Enzymes speed up chemical reactions by lowering the reaction’s activation energy.

What is an Enzyme? A biological catalyst that accelerates a chemical reaction without being used up in the reaction  Most enzymes are proteins  Enzymes have shape - each enzyme has a specific shape, which makes each enzyme unique to which substrate (reactant) it can bind with to catalyze a reaction.

Substrate (reactant) protein + Trypsin >>>>>> A.A. + Trypsin Enzyme Complex Products Enzyme ++

Factors that affect enzyme activity

1. Temperature As temperature increases so does the movement of molecules, resulting in faster rxn rates. However, an extreme temp change may denature the enzyme and cause the rxn rate to drop. Temperature Rxn Rate

2. pH pH Rxn Rate Pepsin Trypsin Enzymes will operate at a specific pH range. If there is an extreme change in pH then the enzyme could be denatured (lose its normal shape and function).

3. Substrate concentration Substrate concentration Rxn Rate As substrate concentration increases the rxn rate increases until the enzymes become saturated

4. Enzyme concentration As enzyme concentration increases the rxn rate increases if there is an excess of substrate Enzyme concentration Rxn Rate

Some enzymes require helper molecules Cofactors - metal ions such as Ca 2+ and Mg 2+ - bind to the active site of the enzyme to provide a better fit - maintain the active site to prep the enzyme for the next reaction

Coenzymes - non-protein molecules that help enzyme-catalyzed reactions 1. Some coenzymes are derived from B vitamins and are electron carriers. NAD + (nicotinamide adenine dinucleotide) made form vitamin B3 (Niacin) FAD + (flavin adenine dinucleotide) made from vitamin B ( Riboflavin) Both of these accept H e- during glucose catabolism and transfer their e- to another molecule in the ETC to release its energy. NAD + + H NADH and FAD + + 2H FADH 2

Similar to NAD +, but the H e- that it accepts is used to reduce CO 2 into carbohydrate during photosynthesis. More Coenzymes NADP + (nicotinamide adenine dinucleotide phosphate) Coenzyme A - interacts with the substrate acetic acid to make it become more reactive to enter the Kreb’s Cycle of aerobic respiration.