Chapter 6 - Energy & Metabolism Flashcards Preview

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Flashcards in Chapter 6 - Energy & Metabolism Deck (31):
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.

Free energy

2

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

Endergonic reaction

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.

Exergonic reaction

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.

Spontaneous reaction

5

Equilibrium Constant

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.

6

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

Activation evergy

7

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

Catalyst

8

ATP Composition

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

9

ATP

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

10

ADP

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

11

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

Enzyme

12

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

Enzyme substrate complex

13

Foundation to which an organism is attached.

Substrate

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.

Active site

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.

Induced fit

16

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

Multienzyme complex

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.

ribozyme

18

Substance that binds to an enzyme and decreases its activity.

Inhibitor

19

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

Competitive inhibitors

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.

Noncompetitive inhibitors

21

Enzymes that can exist in either active or inactive conformation.

Allosteric enzyme

22

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

Allosteric site

23

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

Allosteric inhibitor

24

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

Allosteric activator

25

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

Cofactor
(eg: zinc and protein digestion)

26

When a cofactor is a nonprotein organic molecule.
(eg:)

Coenzyme
(eg: B vitamins, modified nucleotides)

27

Total of all chemical reactions by an organism.

Metabolism

28

Chemical reactions that expend energy to build up molecules.

Anabolism

29

Reactions that harvest energy by breaking down molecules.

Catabolic reactions

30

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

Biochemical pathways

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.

Feedback inhibitions