Ch 3 - Energy, Catalysis and Biosynthesis

Question 1

acetyl CoA

Answer 1

activated carrier that donates the carbon atom in its readily transferable acetyl group to many metabolic reactions, including the citric acid cycle and fatty acid biosynthesis; the acetyl group is linked to CoEnzyme A (CoA) by a thioester bond that releases a large amount of energy when hydrolyzed

Question 2

activated carrier

Answer 2

a small molecule that stores energy or chemical groups in a form that can be donated to many different metabolic reactions. examples include ATP, acetyl CoA and NADH

Question 3

activation energy

Answer 3

the energy that must be acquired by a molecule to undergo a chemical reaction

Question 4

anabolism

Answer 4

set of metabolic pathways by which large molecules are made from smaller ones

Question 4

ADP, ATP

Answer 4

ADP - nucleoside diphosphate produced by hydrolysis of the terminal phosphate of ATP

Question 5

biosynthesis

Answer 5

an enzyme-catalyzed process by which complex molecules are formed from simpler substances by living cells; also called anabolism

Question 6

catabolism

Answer 6

set of enzyme-catalyzed reactions by which complex molecules are degraded to simpler ones with release of energy; intermediates i these reactions are sometimes called catabolites

Question 7

catalyst

Answer 7

substance that accelerates a chemical reaction by lowering its activation energy; enzymes perform this role in cells

Question 8

cell respiration

Answer 8

process by which cells harvest the energy stored in food molecules; usually accompanied by the uptake of O2 and the release of CO2

Question 9

coupled reaction

Answer 9

linked pair of chemical reactions in which free energy released by one reaction serves to drive the other reaction

Question 10

diffusion

Answer 10

process by which molecules and small particles move from one location to another by random, thermally driven motion

Question 11

entropy

Answer 11

thermodynamic quantity that measures the degree of disorder in a system

Question 12

enzyme

Answer 12

a protein that catalyzes a specific chemical reaction

Question 13

equilibrium

Answer 13

state in which the forward and reverse rates of a chemical reaction are equal so that no net chemical change occurs

Question 14

equilibrium constant K

Answer 14

for a reversible chemical reaction, the ratio of substrate to product when the rates of the forward and reverse reactions are equal

Question 15

free energy G

Answer 15

energy that can be harnessed to do work, such as driving a chemical reaction

Question 16

free-energy change (∆G)

Answer 16

in a chemical reaction, the difference in free energy between reactant and product molecules. a large negative value of ∆G indicates that the rection has a strong tendency to occur

Question 17

metabolism

Answer 17

the sum total of the chemical reactions that take place in the cells of a living organism

Question 18

NAD+, NADH

Answer 18

a molecule that accepts a hydride ion (H-) from a donor molecule, thereby producing the activated carrier NADH. widely used in the energy-producing breakdown of sugar molecules

Question 19

NADP+, NADPH

Answer 19

molecule that accepts a hydride ion (H-) from a donor molecule, thereby producing the activated carrier NADPH; widely used as an electron donor in biosynthetic pathways

Question 20

oxidation

Answer 20

removal of electrons from an atom, as occurs during the addition of oxygen to a carbon atom or when a hydrogen is removed from a carbon atom; can also refer to a partial shift of electrons between atoms linked by a covalent bond

Question 21

photosynthesis

Answer 21

the process by which plants, algae and some bacteria use the energy of sunlight to drive the synthesis of organic molecules from carbon dioxide and water

Question 22

reduction

Answer 22

addition of electrons to an atom, as occurs during the addition of hydrogen to a carbon atom or the removal of oxygen from it; can also refer to a partial shift of electrons between atoms linked by a covalent bond

Question 23

standard free-energy change (∆G°)

Answer 23

the free-energy change measured at a defined concentration, temperature and pressure

Question 24

substrate

Answer 24

a molecule on which an enzyme acts to catalyze a chemical reaction