METABOLISM ENERGY All living things need energy No

METABOLISM

ENERGY All living things need energy No Energy= Death!!! Free energy is energy available for work Chemical energy is energy stored in chemical bonds of molecules What is the main source of energy for all life on earth?

FLOW OF ENERGY THROUGH LIFE organic molecules ATP & organic molecules sun solar energy ATP & organic molecules ATP & organic molecules

CHEMICAL REACTIONS Reactants PRODUCTS CH 4 + 2 O 2 CO 2 + 2 H 2 O Living things are energy converters Light energy chemical energy electric energy

LAWS OF THERMODYNAMICS First law…Law of Conservation of Energy *Energy cannot be created or destroyed only transferred or transformed Why is this statement incorrect: Plants create their own energy. Second law…Entropy –Every chemical reaction increases disorder in the universe –With every chemical reaction that transfers/transforms energy, some of that energy is converted into thermal energy and lost as heat

METABOLISM What is metabolism?

METABOLISM Metabolism is all of the chemical reactions occurring in a biological system at a given time *Involves energy changes -Energy is either stored in chemical bonds or -Energy is released from chemical bonds 2 parts to metabolism -Anabolic pathways -Catabolic pathways

ANABOLIC PATHWAY Anabolic pathways…consume (use) energy to build complex molecules from simpler ones Sound familiar? Other examples? Keys to identify…Look for -Building or synthesizing -Require energy Why?

CATABOLIC PATHWAY Catabolic pathways…release energy by breaking down complex molecules into simpler compounds Again…sound familiar? Keys to identify…Look for Breakdown or decomposition Release energy Why?

CATABOLIC AND ANABOLIC COUPLING In organisms, catabolic reactions are used to drive anabolic reactions + + + energy

EXERGONIC REACTIONS Exergonic Chemical reactions that release free energy Connected to… Example?

ENDERGONIC REACTIONS Endergonic Chemical reactions that absorb free energy Connected to… Example?

(b) Endergonic reaction: energy required, nonspontaneous Free energy Products Reactants Energy Progress of the reaction Amount of energy required ( G 0)

(a) Exergonic reaction: energy released, spontaneous Free energy Reactants Energy Progress of the reaction Amount of energy released ( G 0) Products

METABOLIC PATHWAYS Series of chemical reactions (anabolic and catabolic) in which the products of one reaction becomes the reactants of the next *Controlled by enzymes Hundreds of enzymes in each cell are involved in interconnecting pathways Metabolite= a molecule in a metabolic pathway

CONTROL OF PATHWAYS To control metabolic pathways the cell regulates the amounts of enzymes involved in each pathway 2 ways: Turn the genes on or off that build enzyme Turn enzymes on or off