Chapter 8: An Introduction to Metabolism

Question 1

Metabolism

Answer 1

• All of an organism’s chemical reactions

- Consisting of catabolic and anabolic pathways, which manage the material and energy resources of the organelles

Question 2

Metabolic Pathway

Answer 2

Series of chemical reactions that either builds a complex molecule or breaks down a complex molecule to simpler molecules

Question 3

Catabolic Pathway

Answer 3

A metabolic pathway that releases energy by breaking down complex molecules to simpler compounds

Question 4

Anabolic Pathway

Answer 4

Metabolic pathway that consumes energy to synthesize a complex molecule from simpler molecules

Question 5

Bioenergetics

Answer 5

• Overall flow and transformation of energy in an organism

- Study of how energy flows through organisms

Question 6

Energy

Answer 6

The capacity to cause change, especially to do work

Question 7

Kinetic Energy

Answer 7

The energy associated with the relative motion of objects

Question 8

Thermal Energy

Answer 8

• Kinetic energy due to the random motion of atoms and molecules
• Energy in its most random form

Question 9

Heat

Answer 9

Thermal energy in transfer from one body of matter to another

Question 10

Potential Energy

Answer 10

The energy that matter possesses as a result of its location or spatial arrangement (structure)

Question 11

Chemical Energy

Answer 11

• Energy available in molecules for release in a chemical reaction
• A form of potential energy

Question 12

Thermodynamics

Answer 12

The study of energy transformations that occur in a collection of matter

Question 13

First Law of Thermodynamics

Answer 13

• The principle of conservation of energy

- Energy can be transferred and transformed, but it cannot be created or destroyed

Question 14

Entropy

Answer 14

A measure of disorder or randomness

Question 15

Second Law of Thermodynamics

Answer 15

• The principle stating that every energy transfer or transformation increases the entropy of the universe
• Usable forms of energy are at least partly converted to heat

Question 16

Spontaneous Process

Answer 16

• A process that occurs without an overall input of energy

- A process that is energetically favorable

Question 17

Free Energy

Answer 17

The portion of a biological system’s energy that can perform work when temperature and pressure are uniform throughout the system

Question 18

Exergonic Reaction

Answer 18

A spontaneous chemical reaction in which there is a net release of free energy

Question 19

Endergonic Reaction

Answer 19

A non-spontaneous chemical reaction in which free energy is absorbed from the surroundings

Question 20

Energy Coupling

Answer 20

In cellular metabolism, the use of energy released from an exergonic reaction to drive an endergonic reaction

Question 21

Adenosine Triphosphate (ATP)

Answer 21

• An adenine-containing nucleoside triphosphate that releases free energy when its phosphate bonds are hydrolyzed
• This energy is used to drive endergonic reactions in cells

Question 22

Phosphorylated Intermediate

Answer 22

A molecule (often a reactant) with a phosphate group covalently bound to it, making it more reactive (less stable) than the unphosphorylated molecule

Question 23

Enzyme

Answer 23

• Macromolecule serving as a catalyst

- Changes the rate of reaction without being consumed by the reaction

Question 24

Catalyst

Answer 24

Chemical agent that speeds up a reaction without being consumed by the reaction

Question 25

Activation Energy

Answer 25

• The amount of energy that reactants must absorb before a chemical reaction will start
• Also called free energy of activation

Question 26

Substrate

Answer 26

The reactant on which an enzyme works

Question 27

Enzyme-Substrate Complex

Answer 27

Temporary complex formed when an enzyme binds to its substrate molecule(s)

Question 28

Active Site

Answer 28

• Specific region of an enzyme that binds the substrate

- Forms the pocket in which catalysis occurs

Question 29

Induced Fit

Answer 29

• Caused by entry of the substrate

- Change in shape of the active site of an enzyme so that it binds more snugly to the substrate

Question 30

Cofactor

Answer 30

• Any non protein molecule or ion that is required for the proper functioning of an enzyme
• Can be permanently bound to the active site or may bind loosely and reversibly, along with the substrate during catalysis

Question 31

Coenzyme

Answer 31

• An organic molecule serving as a cofactor

- Most vitamins function as coenzymes in metabolic reactions

Question 32

Competitive Inhibitor

Answer 32

Substance that reduces the activity of an enzyme by entering the active site in place of the substrate whose structure it mimics

Question 33

Noncompetitive Inhibitor

Answer 33

• Substance that reduces the activity of an enzyme without entering an active site
• Binds elsewhere on the enzyme
• Changes the shape of the enzyme so the active site no longer effectively catalyzes the conversion of substrate to product

Question 34

Allosteric Regulation

Answer 34

Binding of a regulatory molecule to a protein at one site that affects the function of the protein at a different site

Question 35

Cooperativity

Answer 35

Kind of allosteric regulation whereby a shape change in one subunit of a protein caused by substrate binding is transmitted to all the other subunits, facilitating binding of additional substrate molecules to those subunits

Question 36

Feedback Inhibition

Answer 36

Method of metabolic control in which the end product of a metabolic pathway acts as an inhibitor of an enzyme within that pathway