Biology

1. Chapter 6 Biology

2. Energy 1. Capacity to do work. 2. Kinetic energy is energy of motion. 3. Potential energy is stored energy.

3. Types of energy Used by humans: Gravitational (e.g., hydro, tidal) Kinetic (e.g., wind, waves) Geothermal Nuclear Solar Chemical (combustion of petroleum, coal, gas, wood, H2) Often converted to electricity Used by cells: Chemical energy Breaking of covalent bonds in complex molecules like glucose and ATP

6. Two Laws of Thermodynamics 1. First law of thermodynamics energy cannot be created or destroyed. 2. Second law of thermodynamics energy cannot be changed from one form into another without a loss of usable energy Entropy � measure of disorder (ie. the more random a collection of matter, the greater it�s entropy)

7. Does Life violate the Second law of Thermodynamics?

8. Life ... "define life not by it's substance but by its organization � life in all it's forms has a mechanism for processing energy and information that emerge from some fundamental order in the universe, a new natural law that shapes those forms out of chaos." Byte 1/95 p45

9. Metabolic Reactions and Energy Transformations

11. Metabolism 1. Sum of all the biochemical pathways. 2. Reaction A + B = C + D 3. Free energy (G) is the amount of energy that is free to do work after a chemical reaction.

12. Chemical Reactions Exothermic (exergonic) Endothermic (endergonic)

14. ATP: Energy for Cells ATP (adenosine triphosphate) is the energy currency of cells. When cells require energy, they "spend" ATP.

15. Structure of ATP ATP is called a "high-energy" compound because a phosphate group is easily removed. In cells, about 7.3 kcal per mole is released when ATP is hydrolyzed to ADP + P

16. Structure of ATP ATP is a nucleotide made of base adenine, sugar ribose, and three phosphate groups.

19. Function of ATP 1. Chemical work: ATP supplies energy to synthesize macromolecules that make up the cell. 2. Transport work: ATP supplies energy needed to pump substances across the plasma membrane. 3. Mechanical work: ATP supplies energy to move muscles, cilia and flagella, chromosomes, etc.

20. Metabolic Pathways and Enzymes

21. Reactions in Cells Are Orderly Metabolic pathways are orderly sequence of chemical reactions; each step is catalyzed by a specific enzyme. Reactants ? Products A + B = C + D

22. Reactions in Cells Are Orderly Metabolic energy is captured more easily if it is released in small increments. Each step in a series of chemical reactions is assisted by an enzyme.

24. Reactions in Cells Are Orderly Enzymes are catalysts that speed chemical reactions without the enzyme being changed. Every enzyme is specific in its action and catalyzes only one reaction or one type of reaction. A substrate is a reactant in an enzymatic reaction.

25. Enzymes Lower the Energy of Activation Almost no metabolic reaction occurs in a cell unless its own enzyme is present.

28. Enzyme-Substrate Complexes Every cell reaction requires its specific enzyme; they are named for substrates by adding the ending "-ase "

31. Factors That Affect Enzymatic Speed 1. Moderate Temperature 2. Optimal pH 3. Amount of Active Enzyme

33. Factors That Affect Enzymatic Speed Competitive inhibition, another molecule is similar to enzyme's substrate, competes with true substrate for enzyme's active site, resulting in decreased product formation. Non-competitive inhibition, a molecule binds to allosteric site, a site other than active site, hereby changing the three-dimensional structure of enzyme and ability to bind to its substrate.

34. Factors That Affect Enzymatic Speed Feedback inhibition regulates activity of most enzymes; product produced by an enzyme binds to enzyme's active site. when product is abundant, active sites are full and enzyme activity drops.

39. Factors That Affect Enzymatic Speed Cofactors Help Enzymes many enzymes require an inorganic ion or nonprotein cofactor to function.

40. The End.