Chapter 6 - Energy & Metabolism

Question 1

Amount of work a thermodynamic system can perform. The internal energy of a system minus the amount of energy that cannot be used to perform work.

Answer 1

Free energy

Question 2

A chemical reaction in which the standard change in free energy is positive, and energy is absorbed.

Answer 2

Endergonic reaction

Question 3

A reaction where energy is released. Because the reactants lose energy (G decreases), Gibbs free energy (ΔG) is negative under constant temperature and pressure. These reactions usually do not require energy to proceed, and therefore occur spontaneously.

Answer 3

Exergonic reaction

Question 4

Releases free energy (usually as heat) and moves to a lower, more thermodynamically stable energy state. When ΔG is negative, a process or chemical reaction proceeds spontaneously in the forward direction.

Answer 4

Spontaneous reaction

Question 5

Equilibrium Constant

Answer 5

Chemical reactions are reversible, therefore an exergonic reaction moving in a forward direction will be endergonic in reverse direction. For each reaction, an equilbrium exists. This numerical value is the EC.

Question 6

Extra energy needed to destabilized existing chemical bonds and initiate a chemical reaction.

Answer 6

Activation evergy

Question 7

The substrates that influence chemical bonds in a way that lowers the activation energy needed to initiate a reaction.

Answer 7

Catalyst

Question 8

ATP Composition

Answer 8

Adonisine triphosphate; composed of three smaller components: a five-carbon sugar (ribose), an organic molecule composed of two carbon-nitrogen rings (adenine), and a chain of three phosphates (triphosphate). Stores energy in triphosphates

Question 9

ATP

Answer 9

Stores energy in triphosphate group. When unstable bonds are broken by hydrolysis, energy is released.

Question 10

ADP

Answer 10

When outermost high energy phosphate bond is hydrolyzed, phosphate group is cleaved off the end and becomes ADP (adonisine diphosphate).

Question 11

Protein that is capable of speeding up the specific chemical reactions by lowering the required activation energy.

Answer 11

Enzyme

Question 12

Complex formed when an enzyme binds with its substrate. Often has an altered configuration compared with non-bound enzyme.

Answer 12

Enzyme substrate complex

Question 13

Foundation to which an organism is attached.

Answer 13

Substrate

Question 14

Region of an enzyme surface to which a specific set of substrates binds, lowering the activation energy required for a particular chemical reaction and so facilitating it.

Answer 14

Active site

Question 15

When an enzyme binds to the appropriate substrate, subtle changes in the active site occur. Enhances catalysis, as the enzyme converts substrate to product.

Answer 15

Induced fit

Question 16

Assembly consisting of several enzymes catalyzing different steps in a sequence of reactions. Close proximity speeds process and makes more efficient.

Answer 16

Multienzyme complex

Question 17

RNA molecule that can behave as an enzyme, sometimes catalyzing its own assembly; rRNA also acts as one in polymerization of amino acids to form protein.

Answer 17

ribozyme

Question 18

Substance that binds to an enzyme and decreases its activity.

Answer 18

Inhibitor

Question 19

Compete with the substrate for the same active site, occupying the active site and preventing substrates from biding.

Answer 19

Competitive inhibitors

Question 20

Bind to the enzyme in a location other that the active site, changing the shape of the enzyme and making it unable to bind to a substrate.

Answer 20

Noncompetitive inhibitors

Question 21

Enzymes that can exist in either active or inactive conformation.

Answer 21

Allosteric enzyme

Question 22

Where noncompetative inhibitors bind to a specific portion of the enzyme.

Answer 22

Allosteric site

Question 23

Substance that binds to an allosteric site and reduces enzyme activity.

Answer 23

Allosteric inhibitor

Question 24

Binds to allosteric sites to keep an enzyme in its active configuration, thereby increasing enzyme activity.

Answer 24

Allosteric activator

Question 25

Assist enzyme functions. Can be metal ions that participate in catalysis.
(eg:)

Answer 25

Cofactor

eg: zinc and protein digestion

Question 26

When a cofactor is a nonprotein organic molecule.

eg:

Answer 26

Coenzyme

eg: B vitamins, modified nucleotides

Question 27

Total of all chemical reactions by an organism.

Answer 27

Metabolism

Question 28

Chemical reactions that expend energy to build up molecules.

Answer 28

Anabolism

Question 29

Reactions that harvest energy by breaking down molecules.

Answer 29

Catabolic reactions

Question 30

Product of one chemical reaction becomes substrate for the next. Organizational units of metabolism.

Answer 30

Biochemical pathways

Question 31

Regulation model in which the end-product of a biochemical pathway binds to an allosteric site on the enzyme that catalyzes the first reaction in the pathway.

Answer 31

Feedback inhibitions