Energy and Organisms Ch. 2-2

Importance: -All living organisms use energy. -Amount of energy in the universe remains the same over time, but changes from one form to another. -Biologist study the transfer of energy from the sun to and through almost every organism.

Energy: -Energy is defined as the ability to do work. -Energy occurs in various forms: 1. chemical 2. thermal 3. electrical 4. mechanical 5. radiant

Energy & Chemical Reactions: -Living organisms are constantly undergoing thousands of chemical reactions. -Energy is absorbed (endergonic) or released (exergonic) when chemical bonds are broken and new ones are formed. -Your body takes in carb’s, lipids, and proteins (reactants) and chemically breaks them down into carbon dioxide, water, and other substances (products). -This process is called your metabolism. These reactions release energy which is used to: -maintain body cells, tissues, and organs.

Chemical Reactions and the need of Enzymes: -For a majority of the chemical reactions to occur effectively in our metabolism, energy needs to be added first. This is called the activation energy. -To make the metabolic process more efficient, our bodies created a specialized substance known as a catalyst (enzymes in living organisms) to reduce the amount of activation energy required therefore speeding up the reaction.

Understanding Enzymes: -enzymes are proteins or RNA molecules that speed up metabolic reactions. Enzymes can alter/affect proteins. -enzymes are specific to their job they perform in living organisms. -enzymes generally have the suffix –ase. Example: Lipase -different enzymes have different shapes that are specific to their function. (lock & key model) -enzyme function will vary based upon the temperature or pH level they are exposed to.

Oxidation-Reduction Reactions -Recall: there is a constant transfer of energy into and throughout living organisms. -The chemical reactions that help the transfer of energy involve the transfer of electrons. -These reactions are called Oxidation-Reduction reactions or Redox Reactions. oxidation or being oxidized = reactant loses one or more electrons. reduction or being reduced = reactant gains one or more electrons. -Redox reactions always occur together.