LS2_Ch6Outline - Chapter 6: Energy, Enzymes, and Metabolism...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 6: Energy, Enzymes, and Metabolism 6.1: What physical principles underlie biological energy transformations? Energy: capacity to do work; capacity for change. - Potential energy: stored energy, as in chemical bonds, concentration gradient, and electrical charge imbalance. - Kinetic energy: energy of movement. Energy transformations are linked to the chemical transformations that occur in cells. Metabolism: sum of all total reactions in an organism. - Anabolic reactions: link simple molecules to form more complex molecules; requires energy input and captures it in chemical bonds that are formed (order). - Catabolic reactions: break down complex molecules into simpler ones; release the energy stored in chemical bonds (create disorder). I. First law of thermodynamics: energy is neither created nor destroyed. A. In any conversion of energy from one form to another, the total energy before and after the conversion is the same. II. Second law of thermodynamics: disorder tends to increase. A. When energy is converted from one form into another, some of that energy becomes unavailable to do work; no physical or chemical process is 100% efficient and not all energy released can be converted into work. B. Total energy ( enthalpy, H) includes usable energy that can do work ( free energy, G) and the unusable energy that is lost to disorder ( entropy, S) multiplied by absolute temperature (T). 1. H TotalE = G FreeE + T abs S Entropy 2. Usable energy: G = H – TS 3. Measured in calories (cal) or joules (J). 4. Change in free energy of any chemical reaction is equal to the difference in free energy between the products and reactants: G rxn = G Prod – G Rxtants 5. At constant temperature (whether free energy is released or consumed): G = H – T S a. G < 0: free energy is released. b. G > 0: free energy is required (consumed). III. Chemical reactions release or consume energy A. Exergonic reactions: reactions that release free energy (- G ) such as catabolic reactions (create disorder). B. Endergonic reactions: reactions that require or consume energy (+ G ) such as anabolic reactions (order). C. Chemical equilbrium: static state, state of no net change ( G = 0). 6.2: What is the role of ATP in biochemical energetics? ATP (adenosine triphosphate) : capture and transfer free energy for cells to do chemical work. - Is a nucleotide and can be converted into a building block for nucleic acids. - Releases a large amount of energy when hydrolyzed. - Can phosphorylate (donate a phosphate to) many different molecules. I. ATP hydrolysis releases energy A. Consists of adenine (nitrogenous base) bonded to ribose (sugar) which is attached to a sequence of three phosphate groups. B.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 05/07/2008 for the course LIFESCI 2 taught by Professor Pires during the Spring '08 term at UCLA.

Page1 / 4

LS2_Ch6Outline - Chapter 6: Energy, Enzymes, and Metabolism...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online