READING GUIDE: CH 8 - An Introduction to Metabolism

1) What is meant by “metabolism”? ● Totality of an organisms chemical processes

2) Define the following terms. Give an example of each. ● energy: the capacity to do work ● KE: Energy of movement; Does work that alters state or motion of matter (water rushing through dam) ● PE: stored energy (water behind dam; energy in the chemical bonds of food)

2) Define the following terms. Give an example of each. ● chemical energy: a form of potential energy (stored in chemical bonds of molecules) ● entropy: a measure of disorder, or randomness (the more disorder, the more entropy)

3) Distinguish between catabolic and anabolic pathways 3) Distinguish between catabolic and anabolic pathways. Give an example of each. ● Catabolic pathways: release energy by breaking down complex molecules to simple (EX: cellular respiration) ● Anabolic pathpways: consume/use energy to synthesize complex molecules from simple (EX: photosynthesis or protein synthesis)

4) What is meant by “free energy”? ● FREE ENERGY = portion of a system’s energy available (“free”) to do work (G)

● Entropy (disorder); lost as heat 5) When energy is converted, some becomes unavailable to do work. What is the ultimate fate of this unusable energy? ● Entropy (disorder); lost as heat

6) In the equation: ΔG = ΔH – TΔS, what does each letter represent? ● ΔG: change in free energy ● ΔH: change in total energy (enthalpy) ● T: absolute temp (Kelvin) ● ΔS: change in entropy (disorder)

● *reactions tend to increase entropy (S) (increase disorder) 7) Using the equation in #6, how can we predict whether or not a reaction will be spontaneous? ● If ΔG is negative, free energy is released and the reaction will occur spontaneously; If ΔG is positive, free energy is consumed (NOT spontaneous) ● *reactions tend to increase entropy (S) (increase disorder)

8) Explain and give an example of the following entropy changes: ● *INCREASE IN ENTROPY: products are more disordered than the reactants Example: breakdown/hydrolysis of proteins  amino acids ● *DECREASE IN ENTROPY: products are less disordered than reactants Example: putting together thousands of amino acids  protein

9) Contrast exergonic and endergonic reactions in terms of: free energy, stability, and capacity to do work. Give an example of each. ● Exergonic: release of free energy, negative ΔG; energy made available to do work (cellular respiration; hydrolysis of a protein) ● Endergonic: absorbs / consumes free energy, postive ΔG; stores free energy (photosynthesis; formation of a protein)

10) Summarize the 1st and 2nd Laws of Thermodynamics ● 1st Law: Energy is neither created nor destroyed (total energy before and after a chemical conversion is the same) ● 2nd Law: when energy is converted, some becomes unavailable to do work; every energy transfer increases the entropy of the universe

11) Describe three kinds of work done by a cell. (see sect. 8.3) Mechanical: beating of cilia; moving chromosomes 2. Transport: pumping of substances across a cell membrane 3. Chemical: proteins synthesis, DNA synthesis, anabolic reactions

12) Explain the concept of energy coupling. ● Energy released from an exergonic reaction is used to drive an endergonic reaction (“downhill” process drives “uphill” process) **demo of this at the end!!! 

13) Define phosphorylated. The hydrolysis of ATP releases an inorganic phosphate group and energy; the phosphate group is transferred to another molecule, making it PHOSPHORYLATED. (and more reactive) **nearly all cellular work depends on this process of transferring phosphate groups.

14) Draw and label ONE simplified diagram in which you show an ATP, ADP, and AMP molecule. How are they different? ● ATP = 3 phosphate groups ● ADP = 2 phosphate groups ● AMP = 1 phosphate group

15) Draw and label a simplified diagram of the ATP cycle.

16) (caption of fig. 8.11): Energy released by BREAKDOWN reactions (CATABOLISM) in the cell is used to PHOSPHORYLATE ADP, regenerating ATP. Chemical POTENTIAL energy stored in ATP drive most CELLULAR WORK.

Energy Coupling! **a Rube-Goldberg machine…brought to you by…. OK-GO!