Chapter 6 Flashcards
What is thermodynamics?
Branch of chemistry concerned with energy changes
What are the two states of energy?
- Kinetic – energy of motion
- Potential – stored energy
What is the most convenient way of measuring energy?
Heat
How much energy is required to raise 1 gram of water by 1ºC?
1 calorie
What does a Calorie with a capital C represent?
A kilocalorie
From where does energy flow into the biological world?
The sun
What do photosynthetic organisms do with solar energy?
Capture this energy and store it as potential energy in chemical bonds
What happens during oxidation?
Atom or molecule loses an electron
What happens during reduction?
Atom or molecule gains an electron
What are oxidation-reduction reactions also known as?
Redox reactions
What does the First Law of Thermodynamics state?
Energy cannot be created or destroyed; it can only change from one form to another
What is entropy?
Disorder that is continuously increasing
What does the Second Law of Thermodynamics state?
Energy transformations tend to increase the overall entropy of an isolated system, moving it toward a state of greater disorder or equilibrium.
What is free energy denoted as?
G
What is the equation for free energy?
G = H - TS
What does ΔG represent?
Change in free energy
What indicates a non-spontaneous reaction?
Positive ΔG
What indicates a spontaneous reaction?
Negative ΔG
What is activation energy?
Extra energy required to destabilize existing bonds and initiate a chemical reaction
How can the rate of an exergonic reaction be increased?
- Increasing energy of reacting molecules (heating)
- Lowering activation energy
What are catalysts?
Substances that influence chemical bonds in a way that lowers activation energy
What is ATP?
Adenosine triphosphate, chief currency all cells use
What are the components of ATP?
- Ribose – 5 carbon sugar
- Adenine
- Chain of 3 phosphates
What drives endergonic reactions?
ATP hydrolysis can drive endergonic reactions by coupling the released energy to the energy required for the endergonic process. (exergonic and spontaneous)
What are enzymes?
Biological catalysts, most of which are proteins
What is the function of the active site in enzymes?
Pockets or clefts for substrate binding
What are ribozymes?
Nonprotein enzymes that catalyze reactions in cells
What two types of catalysis do ribozymes perform?
- Intramolecular catalysis
- Intermolecular catalysis
What affects the rate of enzyme-catalyzed reactions?
Concentrations of substrate and enzyme
What is a competitive inhibitor?
Substance that competes with substrate for active site
What is a noncompetitive inhibitor?
Binds to enzyme at a site other than active site, causing shape change
What are allosteric enzymes?
enzymes that can turn on or off depending on whether certain molecules bind to them.
What is metabolism?
Total of all chemical reactions carried out by an organism
What are anabolic reactions?
Reactions that use energy to build up molecules
What are catabolic reactions?
Reactions that harvest energy by breaking down molecules
What is feedback inhibition?
when the final product of a process stops the first step in that process from happening again. It does this by attaching to an enzyme and changing its shape so it no longer works. This helps the cell avoid making too much of something it already has.
