Primary Secondary Tertiary Quaternary Protein Structure

Energy

Outline I. Introduction A. Metabolism B. Energy defined II. Laws of Thermodynamics III. Energy Transfer in Living Systems A. Chemical Reactions B. ATP

Metabolism All the chemical reactions that occur in the cell Capacity to get and use energy to build, store, break down, and eliminate substances necessary for growth and reproduction – Catabolism: reactions that break down large molecules into smaller ones e.g. digestion energy released – Anabolism: reactions that build larger molecules from small ones e.g. protein built from AA subunits energy required

Energy Definition: the ability to do work, cause change Energy obtained from some cellular reactions is used for fueling other reactions Thermodynamics: The study of energy

Laws of Thermodynamics 1 st Law: Energy in the universe is constant – Energy can be transferred or transformed but it cannot be created or destroyed – Also known as the Energy Conservation law – True for a closed system

Heat and Entropy Heat is energy and can do work (steam engine) Conversion of any form or energy into heat is not fully reversible, not all heat is usable energy Heat “lost”=energy no longer capable of doing work Heat is “low quality” energy Unusable heat associated with disorder (entropy) Energy flows from high quality to low quality

Laws of Thermodynamics 1 st Law: Energy in the universe is constant – Energy can be transferred or transformed but it cannot be created or destroyed – Also known as the Energy Conservation law – True for a closed system 2 nd Law: Disorder in the universe is increasing – Entropy: measure of disorder – In a closed system entropy increases

Maintaining Order Systems tend toward disorder How do you explain order of a cell, or an organism? Input of energy required to maintain order

Energy Transfer in Living Systems Each chemical reaction in a cell has reactants and products 2 types of chemical reactions: – Exergonic: energy released meaning reactants have more energy than products. Occur spontaneously – Endergonic: energy required meaning reactants have less energy than products – Sometimes these reactions are coupled

Energy Transfer in Living Systems Metabolic Pathway: series of chemical reactions – Often have reactants which are complexed into one or more intermediates before final products A + B → C → D → E + F Where A, B are reactants C, D are intermediates E,F products Specific enzymes required at each step (each arrow) Chemical equilibrium: recall this occurs when forward and backward reactions occur at the same rate. Concentrations of reactants and products are stable but not necessarily equal

Metabolic Pathway with inhibition (subtraction symbols)

ATP Adenosine triphosphate Nucleotide based molecule- ribose, adenine, and 3 phosphate groups Cellular energy, powers cellular work Bonds between phosphate groups can be broken by hydrolysis ATP + H 2 O ↔ ADP + P i (inorganic phosphate) + energy Phosphate groups all negative-repulse each other, like a coiled spring

ATP molecule

ATP hydrolysis