Lect11_Chemical_Evol

Lect11_Chemical_Evol - All life is chemistry Part 1....

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1 “All life is chemistry” Part 1. Chemical Evolution Extracting and using energy Day 11 Requirements for life • 1. Certain elements (C, H, O, N, S, P or equivalents) – C, H, O, N = 96% of living tissues – With S, P too = 99% • 2. Liquid Water – Universal solvent – Liquid at room temperature (hydrogen bonds) – Temperature stabilizing, cohesion, liquid form most dense Requirements for life 3. A reliable source of high quality energy • Why is energy necessary? – Energy is necessary to create order and perform work. • Life exists only at chemical dis-equilibrium. – Work (movement, formation of polymers, creation of gradients) is not possible without continual energy input. – Once chemical reactions reach equilibrium, high- quality energy is no longer released, and an organism ‘dies’. Today’s goals • 1. Apply the laws of conservation of matter and thermodynamics to living things. • 2. Explain what makes a reaction ‘favorable’ or spontaneous. • 3. Be able to determine whether a reaction takes place quickly or slowly. Laws of Thermodynamics : • 1. Energy cannot be created or destroyed; It Can Only Change Form. (Amount of energy is constant) • 2. As energy changes form, there is an increase in disorder (entropy, S); that is, some energy is converted into non-usable forms ( HEAT, kinetic energy ). • Taken together, these laws state that while the quantity of energy in the universe is constant, the quality is not! Purves et al. 5 th edition. Life: the Science of Biology
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2 Closed vs. Open systems The first and second laws apply to CLOSED systems. The Universe is a closed system Our galaxy is nearly closed, but light comes in from elsewhere Earth is an OPEN system New energy arrives from the sun EVERY DAY Cells are OPEN systems They must take in new energy (food / light) regularly or they will die! Living things create order at the expense of their surroundings!!! The entropy of A CELL (or Earth) plus its surroundings is INCREASING. People need energy to live and grow. Which of the following are energy sources for people? • A. Water • B. Food • C. Nutrients (vitamins, minerals) • D. Exercise • E. Oxygen Humans must eat and breathe in order to live and grow. Are eating and breathing related to each other? • A. Yes •B . N o Respiration • Glucose + (electron acceptor, X2) Æ CO2 + (reduced acceptor, H2X) • Aerobic respiration (one way to extract energy from organic molecules) •G lu co s e
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This note was uploaded on 03/08/2011 for the course BIS 2A taught by Professor Grossberg during the Fall '08 term at UC Davis.

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Lect11_Chemical_Evol - All life is chemistry Part 1....

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