Chapter 8: An Introduction To Metabolism

Question 1

An organism’s metabolism transforms _____ and _____, subject to the laws of thermodynamics.

Answer 1

Matter-Energy

Question 2

Define Metabolism

Answer 2

The totality of an organism’s chemical reactions, consisting of catabolic and anabolic pathways, which manage the material and energy resources of an organism.

Question 3

Define Metabolic Pathway

Answer 3

A series of chemical reactions that either builds a complex molecule (anabolic pathway) or breaks down complex molecules to simpler molecules (catabolic pathway).

Question 4

What is a series of chemical reactions building up a complex molecule called?

Answer 4

Anabolic (Anabolic-Build; think of steroids —-> building muscle)

Question 5

What is a series of chemical reactions breaking down complex molecules into simpler molecules?

Answer 5

Catabolic Pathway

Question 6

Define Catabolic Pathway

Answer 6

A metabolic pathway that RELEASES energy as a result of breaking down complex molecules into simpler ones.

Question 7

What is an example of a catabolic pathway?

Answer 7

Cellular Respiration

Question 8

Define Anabolic Pathway

Answer 8

A metabolic pathway that consumes energy in order to make a complex molecule from simper molecules.

Question 9

Define Bioenergetics

Answer 9

The study of how every flows through living organisms.

Question 10

Define Energy

Answer 10

The capacity to cause change, especially to do work.

Question 11

Define Kinetic Energy

Answer 11

The energy associated with the relative motion of objects.

Question 12

Define Thermal Energy

Answer 12

Energy in its most random form; kinetic energy due to the random motion of molecules and atoms.

Question 13

Define Heat

Answer 13

The transfer of thermal energy from one body of mass to another.

Question 14

Define Potential Energy

Answer 14

The energy that matter possesses ass a result of its location or spatial arrangement.

Question 15

Define Chemical Energy

Answer 15

Energy available in molecules for release in a chemical reaction.

Question 16

Define Thermodynamics

Answer 16

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

Question 17

Scientists use the word _____ to denote the matter under study.

Answer 17

System

Question 18

Define The First Law of Thermodynamics

Answer 18

Energy cannot be created or destroyed; rather, it is transferred and transformed.

Question 19

Define Entropy

Answer 19

A measure of molecular disorder or randomness.

Question 20

Define the Second Law of Thermodynamics

Answer 20

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 20

Define the Second Law of Thermodynamics

Answer 20

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 21

Define Spontaneous Process

Answer 21

A process that occurs without requiring an input of energy.

Question 22

A process that, on its own, leads to a decrease in entropy is said to be _____.

Answer 22

Non-Spontaneous.

Question 23

The _____ of a reaction tells us whether or not the reaction occurs spontaneously.

Answer 23

Free-Energy Change

Question 24

Define Free Energy

Answer 24

The portion of a biological system’s energy that can perform work when temperature and pressure are uniform throughout the system. The change in free energy (Delta G) is equivalent to DeltaH-T Delta (where Delta H is the enthalpy and Delta S is the change in entropy).

Question 25

What does negative Delta G entail?

Answer 25

That the reaction is spontaneous.

Question 26

We can think of free energy as a measure of a system’s _____.

Answer 26

Instability

Question 27

Define Exergonic Reaction

Answer 27

A spontaneous chemical reaction in which there is a net release of energy. DELTA G is NEGATIVE

Question 28

What does the term spontaneous entail?

Answer 28

Energetically Favorable

Question 29

Define Endergonic Reaction

Answer 29

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

Question 30

Is metabolism ever at equilibrium?

Answer 30

No

Question 31

How does ATP power cellular work?

Answer 31

By coupling exergonic reactions to endergonic reactions.

Question 32

What are the three types of work that a cell does?

Answer 32

Chemical-Transport-Mechanical. CTM

Question 33

Define Energy Coupling

Answer 33

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

Question 34

Define ATP (Adenosine Triphosphate)

Answer 34

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

Question 35

Define Phosphorylated Intermediate

Answer 35

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

Question 36

How is ADP used to make ATP again?

Answer 36

The free energy required to phosphorylate ADP comes from exergonic breakdown reactions in the cell.

Question 37

Are catabolic pathways endergonic or exergonic? What about anabolic pathways?

Answer 37

Catabolic is exergonic.

Anabolic is endergonic.

Question 38

Enzymes speed up chemical reactions by _____

Answer 38

Lowering Energy Barriers

Question 39

Define Enzyme

Answer 39

A chemical agent that serves as a catalyst without being consumed by the reaction.

Question 40

Define Catalyst

Answer 40

A chemical agent that selectively increases the rate of a chemical reaction without being consumed by the chemical reaction.

Question 41

Define Activation Energy

Answer 41

The amount of energy that reactants must absorb before a chemical reaction will start; also called free energy of activation.

Question 42

How is the activation energy USUALLY supplied?

Answer 42

It is often supplied by heat in the form of thermal energy.

Question 43

Define Catalysis

Answer 43

A process by which a chemical agent called a catalyst selectively increases the rate of a reaction without being consumed by the reaction.

Question 44

Define Substrate

Answer 44

The reactant on which an enzyme works.

Question 45

Define Enzyme-Substrate Complex

Answer 45

A temporary complex formed when an enzyme binds to its substrate molecules.

Question 46

Define Active Site

Answer 46

The specific region of an enzyme that binds the substrate and that forms the pocket in which catalysis occurs.

Question 47

Define Induced Fit

Answer 47

Caused by entry of the substrate, the change in shape of the active site of an enzyme so that it binds more snugly to the substrate.

Question 48

What are some conditions that can affect the activity of enzymes?

Answer 48

Temperature and pH.

Question 49

In what pH range do most enzymes function the best?

Answer 49

6-8

Question 50

How does temperature affect the activity of enzymes?

Answer 50

Up to a certain point, an increase in temperature increases the activity of the enzymes; however, after a certain point, the activity of the enzymes drops sharply.

Question 51

Define Cofactors

Answer 51

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

Question 52

What are some examples of cofactors?

Answer 52

Metal atoms like zinc, iron, and copper in ionic forms.

Question 53

Define Coenzyme

Answer 53

An organic molecule serving as a cofactor. Most vitamins serve as cofactors in metabolic reactions.

Question 54

Define Competitive Inhibitors

Answer 54

A substance that reduces the activity of an enzyme by entering the active site in place of the substrate, whose structure it mimics.

Question 55

How can competitive inhibitors be overcome?

Answer 55

It can be overcome by increasing the concentration of substrate so that as active sites become more available, more substrate molecules than inhibitor molecules are around to gain entry into the sites.

Question 56

Define Noncompetitive Inhibitors

Answer 56

A substance that reduces the activity of an enzyme by binding to a location remote from the active site, changing the enzyme’s shape so that the active site no longer effectively catalyze the conversion of substrate to product.

Question 57

Define Allosteric Regulation

Answer 57

The binding of a regulatory molecule to a protein at one site that affects the function of the protein at a different site.

Question 58

Define Cooperativity

Answer 58

A 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 59

Define Feedback Inhibition

Answer 59

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

Question 60

In an exergonic reaction, the products have ______ energy than the reactants.

Answer 60

LESS

Question 61

_____ pathways drive regeneration of ATP from ADP+ HOPO3 2-

Answer 61

Catabolic