All living things require energy Intro to Metabolism

The Energy of Life The living cell is a miniature chemical factory where thousands of reactions occur The cell extracts energy and applies energy to perform work

Metabolism is the totality of an organism’s chemical reactions Reactions generally fall into 2 categories Making reactions-require energy Breaking reactions-release energy

Chemical Reaction When one or more substance are converted into different substances with different properties Reactants – substances that undergo a chemical reaction Products – substances that are produced by the reaction

Types of Pathways Catabolic pathways release energy by breaking down complex molecules into simpler compounds Cellular respiration is an example Anabolic pathways consume energy to build complex molecules from simpler ones Photosynthesis is an example Bioenergetics is the study of how organisms manage their energy resources

Chemical Reactions Either Require or Release energy Energy is the capacity to cause change or do work An exergonic reaction proceeds with a net release of energy and is spontaneous (breaking) An endergonic reaction absorbs energy from its surroundings and is nonspontaneous (making)

Laws of Thermodynamics During every energy transfer or transformation, energy is conserved However, some energy is unusable, and is often lost as heat Reactions tend to lose ordered forms of energy

Activation Energy (Ea) Barrier Progress of the reaction Products Reactants ∆G < O Transition state Free energy EA D C B A

Reaction Rate Speed of a chemical reaction The rate of a reaction is determined by how much energy it takes to reach the transition state

Enzymes Catalysts are chemicals that speed up reactions by lowering the activation energy Enzymes are a kind of protein that act as catalysts in biological reactions Each enzyme has an optimal temperature and pH in which it can function

Most Biological reactions occur in many ordered steps A metabolic pathway begins with a specific molecule and ends with a product Each step is catalyzed by a specific enzyme