Biology 123- Dr. Raut’s Class
Session 8- 2/11/2015
1. What are the two types of metabolic pathways?
The two types of metabolic pathways are catabolic pathways and anabolic pathways. Catabolic
pathways break big molecules into smaller molecules and release energy or are spontaneous.
Anabolic pathways build complex molecules out of simpler ones and consumes energy.
2. The study of how energy flows through living organisms is __bioenergetics_.
3. Define the following:
Energy- the capacity to cause change.
Kinetic energy- energy in the form of objects in motion
Heat, or thermal, energy- energy associated with the random movement of atoms or
molecules.
Potential energy- energy that is not kinetic and is energy that matter contains due to
location or structure.
Chemical energy- potential energy available for release in a chemical reaction.
Mechanical energy- sum of kinetic and potential energy, due to motion and location.
4. What is the system? What are the surroundings?
The system is the matter of study. The surroundings are everything outside of the system.
5. True/false: Since cells are selectively permeable, they are a closed system.
False. Cells are an open system because they are constantly exchanging matter with its
surroundings.
6. What is the first law of thermodynamics?
The first law of thermodynamics states that energy can be transferred or transformed but cannot
be created or destroyed. This is also called the principle of conservation of energy.
7. What is the second law of thermodynamics?
The second law of thermodynamics states that every energy transfer or transformation increases
the entropy of the universe.
8. What are the two equations for Gibbs free energy? Be able to determine correlations from the
equations.
ΔG= ΔH – TΔS
ΔG= Gfinal state – Ginitial state
As entropy increases, ΔG becomes more negative, meaning the reaction is more likely to
proceed. ΔH decreases, ΔG decreases.
9. What can the change in free energy tell you?
The change in free energy will tell you if the reaction is spontaneous or not. If he final state has
less free energy than the initial state, then the final state is more stable and less likely to change.
10. Define exergonic and endergonic. Being able to roughly sketch each graph will help you
have a greater understanding.
Exergonic- proceeds with net release of energy and is spontaneous (ΔG<0)
Endergonic- proceeds with energy required and is nonspontaneous (ΔG>0)
11. True or false: Cells never reach equilibrium.
True. If the cell reached equilibrium, then ΔG=0. Everything in the cell would cease, and the cell
would die.
12. What is the energy “currency” for the cell? How is this molecule used?
ATP is the energy “currency for the cell. ATP can by hydrolyzed to produce ADP, inorganic
phosphate, and energy. Energy can then be captured from catabolic pathways and used to reform
ATP from ADP and inorganic phosphate.
13. Enzymes act as a biological __catalysts__. What does this mean?
Being a biological catalysts means that an enzyme is a chemical agent that helps to speed up a
reaction without being consumed by the reaction.
14. How does an enzyme increase the rate and ease of a reaction? Being able to draw and label a
graph will help you have a greater understanding.
An enzyme increases the rate of reaction by lowering the activation energy.
15. What are the ways that the active site of an enzyme lower the activation energy?
The active site of an enzyme lowers the activation energy by orienting the substrate to a position
that will allow it to react easier, by straining bonds which must be broken during the reaction, by
providing a favorable microenvironment, and by forming brief covalent bonds with the substrate.
16. What is a cofactor? What is a coenzyme?
A cofactor is a non-protein enzyme helper, often inorganic ions. A coenzyme is a cofactor that is
an organic molecule, often a vitamin.
17. Catabolic and anabolic pathways are often coupled in a cell because
a. the intermediates of a catabolic pathway are used in the anabolic pathways.
b. both pathways use the same enzymes.
c. the free energy released from one pathway is used to drive the other pathway.
d. the activation energy of the catabolic pathway can be used in the anabolic pathway.
e. their enzymes are controlled by the same activators and inhibitors.
18. When glucose and O2 are converted to CO2 and H2O, changes in total energy, entropy, and
free energy are correctly represented as
a. –Δ H, - ΔS, - ΔG
b. –Δ H, + ΔS, - ΔG
c. –Δ H, + ΔS, + ΔG
d. +Δ H, + ΔS, + ΔG
e. +Δ H, - ΔS, + ΔG
19. A negative Δ G means that
a. the quantity G of energy is available to do work.
b. the reaction is spontaneous.
c. the reactants have more free energy than the products.
d. the reaction is exergonic.
e. all of the above are true.