Chapter 6 Flashcards
(15 cards)
Summarize the Second Law of Thermodynamics and include a definition of Entropy (S)
Energy transfer or transformation increases a system’s disorder, called entropy.
Entropy: Measure of randomness of molecules in a system
Explain how energy coupling is used to get an endergonic reaction to occur. Which molecule is often broken down to power an endergonic reaction?
An endergonic reaction occurs spontaneously if coupled with an exergonic reaction and both energy total change is negative.
Define metabolism and distinguish catabolic and anabolic pathways
Metabolism: the sum total of all chemical reactions that occur within an organism
Catabolism: breakdown of molecules
Anabolic: synthesis of molecules
Define equilibrium and explain why most reactions in living systems avoid equilibrium.
Equilibrium: a state in which opposing forces or influences are balanced
Cells are open systems, constantly exchanging materials/energy, never staying stable
Explain the statement– Homeostasis and equilibrium are not the same
Explain how activation energy determines the rate of the reaction, and give an example of a source of activation energy
Activation energy: allows molecules to get close enough causing rearrangement of bonds
Higher activation energy: slower the reaction
Lower activation energy: faster the reaction
Ex: heat
Explain why cold temperatures slow chemical reactions.
Molecules move slower and collide less often. Less activation energy
Define the terms catalyst and enzyme. Explain how an enzyme increases the rate of a biochemical reaction, including the effect the enzyme has on activation energy.
Catalyst: speeds up the rate of a chemical reaction without changes or consumption by it
Enzyme: proteins
Enzyme speeds up biochemical reactions, lowering activation energy: easier for molecules to react.
Explain why enzymes catalyze one specific chemical reaction
Enzymes catalyze one specific reaction because their shape fits only certain molecules.
Explain how substrate concentration and enzyme inhibitors can affect the rate of an enzyme-catalyzed reaction.
-Higher substrate concentration speeds up reaction, but too much can slow it
-Inhibitors slow or stop the enzyme by blocking enzyme’s activity
Compare and contrast competitive inhibitors and noncompetitive inhibitors. Connect it to enzyme shape, inhibitor shape and enzyme binding sites (active sites, allosteric sites).
Competitive inhibitors:
-block the enzyme’s active site, competing with the substrate.
Noncompetitive inhibitors:
- bind to allosteric site, changing enzyme’s shape and affecting its function in catalyzing
Define Feedback Inhibition
When the end product of a reaction slows or stops the enzyme to prevent overproduction.
Summarize two ways that ATP is made in the cell.
Substrate level Phosphorylation: An enzyme transfers a phosphate from an organic molecule to ADP to make ATP
Chemiosmosis: Energy stored in an ion electrochemical gradient is used to make ATP from ADP and Pi
Define energy intermediate and identify two examples of energy intermediates used in the cell
A molecule that temporarily stores and transfers energy in cells
-ATP
-NADH
Explain how electron movement is related to reduction-oxidation (redox) reactions and relate it to energy transfer.
*In redox reactions, electrons are transferred between molecules.
Reduction: addition of electrons from a molecule/atom
Oxidation: removal of electrons from a molecule/atom
