Biology 114 Exam 2 Questions and
Answers
Metabolism
✓ ~~~Biological Chemical reactions. The totality of an organism's chemical reaction.
The Concept of Free Energy
✓ ~~~Free energy is the portion of a system's energy that can perform work when the
temperature and pressure are uniform throughout the system, as in a living cell.
∆G
✓ ~~~the change in free energy. We can use it to predict whether the process will be
spontaneous.
Exergonic
✓ ~~~"energy outward" An ergonomic reaction proceeds with a net release of free energy.
∆G is negative, these occur spontaneously.
Endergonic
✓ ~~~A reaction that absorbs free energy from its surroundings. This type of reaction stores
energy in molecules. ∆G is positive, these are nonspontaenous.
Enzymes
✓ ~~~Macromolecules that act like a catalyst in order to speed of the rate of a reaction
without being consumed by the reaction.
What happens without enzymes?
✓ ~~~metabolic pathways would become clustered.
,Activation Energy
✓ ~~~The amount of energy needed to start a reaction.
How is activation energy supplied?
✓ ~~~In the form of heat.
How does activation energy relate to the role of enzymes?
✓ ~~~Activation energy provides a barrier that determines the rate of the reaction.
How do cells get the necessary energy to drive non spontaneous reactions?
✓ ~~~An example would be plants get the required energy from the environment around
them like the sun and turning it into chemical reaction. Next is a series of exergonic steps
to form a glucose modle.
How do enzymes lower E_a?
✓ ~~~By making it possible for a cell to have a dynamic metabolism, routing chemicals
smoothly through cells metabolic pathways. They also determine which chemical
processes will be going on in a cell.
How do enzymes function?
✓ ~~~They bind to a substrate forming an enzyme substrate complex.
What factors influence enzyme activity?
✓ ~~~Environmental conditions, cofactors, and enzyme inhibitors
Competitive Inhibitors:
✓ ~~~Reduces the productivity go enzymes by blocking substrates from entering active
sites.
, Non-competitive Inhibitors:
✓ ~~~These do not directly compete with the substrate to bing to the enzyme at the active
site. This inhibitor causes enzymes to change shape.
Allosteric Regulation:
✓ ~~~Describes any cause in which a protein's function at one site is affected by the binding
of a molecule to a separate site.
Positive Allosteric Regulation:
✓ ~~~Binding of an activator to a regulatory site which stabilizes the shape that has
functional active sites.
Negative Allosteric Regulation:
✓ ~~~Binding of an inhibitor, which stabilizes the inactive form of the enzyme.
Feedback Inhibition:
✓ ~~~When ATP inhibits an enzyme in and ATP generating pathway the result is feedback
inhibition.
What is feedback inhibition. common control of?
✓ ~~~Metabolic control
What does feedback inhibition prevent?
✓ ~~~The cell from wasting chemical resources.
What is oxidative phosphorylation?
✓ ~~~ATP synthesis that is powered by the transfer of electrons from glucose to oxygen.
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