BI105_FA24_14 Energy and Enzymes I PDF

ENERGY RELATIONSHIPS AND METABOLISM  ENERGY IS THE C APACITY TO PERFORM WORK The most basic types of energy are: Kinetic energy: the energy of motion. Potential energy: energy stored in something’s structure or position. These types of energy can be converted into one another and...

ENERGY RELATIONSHIPS AND METABOLISM  ENERGY IS THE C APACITY TO PERFORM WORK The most basic types of energy are: Kinetic energy: the energy of motion. Potential energy: energy stored in something’s structure or position. These types of energy can be converted into one another and transferred between objects – these are forms of work. All organisms require energy to grow, move, and change IMPORTANT TYPES OF ENERGY FOR LIVING ORGANISMS Kinetic energy of movement – important for animal behavior. IMPORTANT TYPES OF ENERGY FOR LIVING ORGANISMS Thermal energy is a type of kinetic energy associated with the random movement of atoms/molecules. Thermal energy that is transferred from one object to another is heat. Energy is often lost from biological systems in the form of heat.  IMPORTANT TYPES OF ENERGY FOR LIVING ORGANISMS Chemical potential energy is the potential energy stored in the bonds of a molecule, which can be released in a chemical reaction. The most important type of energy for living organisms, which powers work done by all living cells. Other forms of energy can be very important in biology (e.g. light), but we will skip them for now. Depends both on the chemicals present in the food and on which chemicals we can effectively break down in our digestive system Calories are an estimate of the chemical potential energy in the food that is available to the human body  THE BRANCH OF PHYSICS CONCERNED WITH STUDYING ENERGY TRANSFORMATIONS IS THERMODYNAMICS Two critical laws of thermodynamics 1st law of thermodynamics: “law of conservation of energy”. energy can be neither created nor destroyed—just converted from one form to another.  ENERGY IS CONSTANTLY BEING CHANGED FROM ONE FORM TO ANOTHER Chemical potential energy in bonds of food Kinetic energy of muscle contraction Kinetic energy of the flying arrow Potential energy stored in the bent bow ENERGY TRANSFORMATIONS POWER WORK DONE BY HUMAN BODIES AND HUMAN TECHNOLOGIES  THE BRANCH OF PHYSICS CONCERNED WITH STUDYING ENERGY TRANSFORMATIONS IS THERMODYNAMICS Two critical laws of thermodynamics 2nd law of thermodynamics: when energy is converted from one form to another, some of that energy becomes unavailable to do work. As entropy increases, less energy is available for organisms to do work (less free energy [G] is available). In a biological context, energy is lost to the environment as heat ENERGY AND CHEMICAL REACTIONS MOST BIOLOGIC AL REACTIONS ARE REVERSIBLE Going this way →: Going this way ←: forms breaks high energy high energy bonds and bonds and releases a requires a lot of energy lot of energy (burning input (e.g. heating: methane as fuel) carbon capture)  BASIC THERMODYNAMICS IS CRITIC AL FOR UNDERSTANDING HOW CHEMIC AL REACTIONS OCCUR If more chemical energy in the It will be converted into some bonds of A&B than C&D, where other form and released does the extra energy go? energy A+B C+D 1) Energy is neither created nor destroyed. 2) Different chemical bonds in these molecules contain different amounts of chemical energy.  BASIC THERMODYNAMICS IS CRITIC AL FOR UNDERSTANDING HOW CHEMIC AL REACTIONS OCCUR Imagine a reaction that involves four different molecules: If less chemical energy in the bonds of A&B than C&D, where does the extra energy come from? It will need to be added to the reaction energy A+B C+D 1) Energy is neither created nor destroyed. 2) Different chemical bonds in these molecules contain different amounts of chemical energy.  REACTIONS THAT RELEASE ENERGY ARE EXERGONIC; REACTIONS THAT REQUIRE ENERGY ARE ENDERGONIC energy A+B C+D Exergonic energy A+B C+D Endergonic QUESTIONS? TOPHAT QUESTION 14.1 METABOLISM  METABOLISM IS THE SUM OF ALL CHEMICAL REACTIONS WITHIN CELLS OF LIVING ORGANISMS Two categories of metabolic reactions: Catabolism: the breakdown of a molecule into smaller components. These are generally exergonic reactions Anabolism: synthesis of molecules from smaller precursors. These are generally endergonic reactions  WHERE DO ORGANISMS GET THE ENERGY REQUIRED FOR ALL THE ENDERGONIC REACTIONS NEEDED FOR LIFE? They couple an exergonic and endergonic reaction at the same place/time, and use the energy released from the first to fuel the second. One specific exergonic reaction is used for this purpose overwhelmingly across living organisms: the hydrolysis of ATP. In other words, ATP is a general-purpose energy storage molecule: it can be used to drive many endergonic reactions in a cell  THE HYDROLYSIS OF ATP ATP is a modified nucleotide with extra high-energy phosphate groups This liberated energy is what is used to drive Adenosine triphosphate (ATP) other endergonic reactions Energy Inorganic phosphate Adenosine diphosphate (ADP) Uses of ATP that we have already POLYMERIZATION AND encountered: DEPOLYMERIZATION Building a polymer from monomers is usually done by dehydration reactions ATP ATP drives most anabolic reactions inside cells ADP + Pi Uses of ATP that we have already encountered: MOTOR PROTEINS ATP ADP + Pi ATP powers intracellular transport Uses of ATP that we have PUMPS AND MEMBRANES C AN BE USED TO CONVERT STORED CHEMIC AL ENERGY FROM already ATP TO POTENTIAL ENERGY IN THE FORM OF encountered: A CONCENTRATION GRADIENT  CELLS REPLENISH THEIR SUPPLY OF ATP BY HARNESSING THE ENERGY OF C ATABOLIC ALLY BREAKING DOWN OTHER SUBSTANCES Cells must do this constantly since they ATP H2O are using ATP constantly to live Energy from Energy for cellular catabolism (exergonic, work (endergonic, energy-releasing ADP Pi energy-consuming processes) processes) We will discuss how we “recharge” ATP using the food we eat when we cover cellular respiration starting in the next lecture QUESTIONS?