A hallmark of life is its ability to transform molecules. Biochemical CHanges A hallmark of life is its ability to transform molecules.

Sucrose + H2O Glucose + Fructose Chemical Reaction Occurs when atoms have sufficient energy to combine, break apart, or switch bonding partners. Sucrose + H2O Glucose + Fructose Reactants Products The products have different properties than the reactants even though they are made of the same elements in different combinations. Chemical reactions involve changes in energy.

What is Energy? In Biochemistry … Two Types of Energy Potential Energy Consider energy as the capacity for change. Two Types of Energy Potential Energy Stored energy Kinetic Energy Energy that does work Potential Energy can be converted to Kinetic Energy, and Kinetic Energy can be converted to Potential Energy.

Metabolism The sum total of all the chemical reactions occurring in a biological system at a given time. Involves energy changes in which energy is either stored in, or released from, chemical bonds. Formations of a bond releases energy Breaking of a bond requires an input of energy A chemical reaction will occur spontaneously if the total energy consumed by breaking bonds in the reactants is less than the total energy released by forming bonds in the product.

Metabolism Anabolic Reactions Link simple molecules to form more complex molecules. Requires an input of energy because strong bonds must be broken. Called endergonic or endothermic reactions Energy used in the anabolic reactions is stored in the chemical bonds.

Metabolism Catabolic Reactions Breaks down complex molecules into simpler ones and releases the energy used to make the complex molecule. Called exergonic or exothermic reactions. Energy is released.

Metabolism Catabolic and Anabolic reactions are often linked together. Energy released in catabolic reactions often drives anabolic reactions.

Biochemical changes obey physical laws. First Law of Thermodynamics Energy is neither created or destroyed. Although the total amount of energy is conserved, chemical reactions involve changes in the amount of (potential) energy stored in chemical bonds.

Biochemical changes obey physical laws. Second Law of Thermodynamics Useful energy tends to decrease When energy is converted some of it becomes useless to do work. Energy is lost to disorder. Entropy: measure of the disorder of a system Energy is used to generate and maintain order, biological processes cause an overall increase in entropy.

Homework Diagram figure 2.14 Energy Changes Reaction and give a brief description of each one. Diagram figure 2.15 The Laws of Thermodynamics and give a brief description of each one. Complete the CHECKpoint Concept 2.5 questions (3) on page 34 and complete the applying the concept activity also on page 34.