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 organic molecules  ATP & organic molecules organic molecules  ATP & organic molecules sun organic molecules  ATP & organic molecules solar energy  ATP & organic molecules

Chemical Reactions Reactants PRODUCTS CH4 + 2O2 CO2 + 2H2O 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 + + energy + +

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

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

Amount of energy required (G  0) (b) Endergonic reaction: energy required, nonspontaneous Products Amount of energy required (G  0) Energy Free energy Reactants Figure 6.6b Free energy changes (ΔG) in exergonic and endergonic reactions (part 2: endergonic) Progress of the reaction 13

Amount of energy released (G  0) (a) Exergonic reaction: energy released, spontaneous Reactants Amount of energy released (G  0) Energy Free energy Products Figure 6.6a Free energy changes (ΔG) in exergonic and endergonic reactions (part 1: exergonic) Progress of the reaction 14

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 inter-connecting 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