Biology 100 Chapter 6

Front 1

energy

Back 1

the capacity to bring about movement against an opposing force

Front 2

potential energy

Back 2

stored energy: the rock perched precariously at the top of the hill; the charged ions kept on one side of a cell membrane

Front 3

kinetic energy

Back 3

energy in motion, as with the rock tumbling down the hill or charged ions rushing in through a protein channel

Front 4

thermodynamics

Back 4

the study of energy

Front 5

first law of thermodynamics

Back 5

energy is never created or destroyed

Front 6

second law of themodynamics

Back 6

energy transfer always results in a greater amount of disorder in the universe

Front 7

energy transformed

Back 7

in a steam engine, energy locked up in the chemical bonds of coal is transformed into heat energy and mechanical energy. No energy is lost in this process, but energy is transformed from a more ordered form (the chemical bonds of coal) to a less ordered form (heat). Thus, the amount of disorder-or entropy-increases in the transaction.

Front 8

exergonic reactions

Back 8

reactions in which the starting set of molecules (the reactants) contains more energy than the final set of molecules (the products)

Front 9

endergonic reactions

Back 9

reactions in which the products contain more energy than the reactants.

Front 10

energy stored and released

Back 10

it takes energy to build up a more complex molecule (in this case, glycogen) from simpler molecules (in this case, glucose units). such a buildup is thus an endergonic or uphill reaction. conversely, energy is released in reactions in which more complex molecules are broken down into simpler ones. such reactions are exergonic or downhill reactions

Front 11

coupled reaction

Back 11

chemical reaction in which an exergonic reaction powers an endergonic reaction

Front 12

ATP (adenosine triphosphate)

Back 12

ATP stores energy in the form of chemical bonds between phosphate groups. When the bond between the second and outermost phosphate group is broken, the outermost phosphate separates from ATP, and energy is released. This separation transforms ATP into ADP, which then goes on to pick up another phosphate group, becoming ATP again.

Front 13

enzyme

Back 13

a type of protein that accelerates a chemical reaction

Front 14

substrate

Back 14

a substance whose chemical alteration is facilitated by an enzyme

Front 15

matabolic pathway

Back 15

a sequential set of enzymatically controlled chemical reactions in which the product of one reaction serves as the substrate for the next

Front 16

metabolism

Back 16

the sum of all chemical reactions carried out by a cell or larger organism

Front 17

activation energy

Back 17

the energy required to initiate a chemical reaction. Enzymes lower the activation energy of a reaction, thereby greatly speeding up the rate of the reaction

Front 18

catalysts

Back 18

a substance that retains its original chemical composition while bringing about a change in a substrate. enzymes are catalysts in chemical reactions; one enzyme can carry out hundreds or thousands of chemical transformations without itself being transformed.

Front 19

active site

Back 19

the portion of an enzyme that binds with a substrate, thus helping transform it

Front 20

co-enzymes

Back 20

a type of accessory molecule that binds to the active site of an enzyme, thus allowing the enzyme to bind to its substrate. many vitamins are coenzymes

Front 21

competitive inhibition

Back 21

a reduction in the activity of an enzyme by means of a compound other than the enzyme's usual substrate binding with it in its active site

Front 22

allosteric regulation

Back 22

the regulation of an enzyme's activity by means of a molecule binding to a site on the enzyme other than its active site

Front 23

enzyme chymotrypsin

Back 23

the enzyme chymotrypsin is facilitating the breakdown of a protein by changing the protein's shape. in the absence of chymotrypsin, the process wold take a billion times longer