Chapter 8

Question 1

Living cell is a …

Answer 1

miniature factory where thousands of reactions occur that convert energy into work

Question 2

Energy

Answer 2

the capacity to do work

Question 3

Some organisms can convert ___ to light

Answer 3

energy to light

i.e. bioluminescent of jellyfish

Question 4

Some organisms can convert light into___

Answer 4

chemical energy

i.e. in plants

Question 5

Organism’s metabolism

Answer 5

transforms matter and energy, subject to the laws of thermo, into the ability to perform work

Question 6

Metabolism

Answer 6

the totality of an organism’s chemical reactions that arises from interactions between molecules

Question 7

Metabolic Pathway

Answer 7

has multiple steps that begin with a specific molecule and end with a product that is catalyzed by specific enzymes (highly specific)

Question 8

Catabolic Pathways

Answer 8

break down complex molecules into simpler compounds during a process that release energy

i.e. during cellular respiration, glucose i broken down into CO2 and H2O in the presence of O2

Question 9

Anabolic Pathways

Answer 9

build complicated molecules from simpler ones during a process that consumes energy

Question 10

Energy

Answer 10

• the capacity to cause change and exists in various forms some of which can perform work
• can be converted from one form to another

Question 11

Kinetic Energy

Answer 11

the energy associated with motion

Question 12

Potential Energy

Answer 12

stored in the location of matter and includes chemical energy stored in molecular structures, such as glucose

Question 13

Thermodynamics

Answer 13

The study of energy transformations and life is subject to the laws of thermodynamics

Question 14

1st Law of Thermodynamics

Answer 14

states that energy can be transferred and transformed, but energy cannot be created or destroyed

(Conservation of energy)

Question 15

Entropy

Answer 15

• the quantity of disorder or randomness

- the more random a collection of matter, the greater the entropy

Question 16

2nd Law of Thermodynamics

Answer 16

states that every energy transfer or transformation increases the entropy of the universe

Question 17

Order may increase locally; however,

Answer 17

the universe tends towards randomness

in other words, spontaneous changes do not require outside energy to increase the entropy, or the amount of disorder

Question 18

Living systems create ordered structures from…

Answer 18

less ordered starting materials and decrease the entropy of the universe and
use energy to maintain order

i.e. aa are ordered into polypeptide chains which are ordered into proteins which are ordered into organelles, etc.

Question 19

Free energy

Answer 19

the energy that can do work under cellular conditions (constant temp and pressure)

Question 20

Free-Energy Change (∆G)

Answer 20

of a reaction tells us whether the reaction is spontaneous or not

Question 21

Spontaneous Reaction

Answer 21

Spontaneous changes do not require energy which is preferred for cellular reactions
(create energy)

Question 22

∆G equation

Answer 22

∆G = ∆H - T∆S

where H = enthalpy
S = entropy

Question 23

Organisms live at the expense of free energy during a spontaneous change,

Answer 23

free energy decreases and the stability (order) of a system increases

i.e. - ∆G becomes a negative #

Question 24

A system at equilibrium is…

Answer 24

at maximum stability

Question 25

2 classifications of chemical reactions

Answer 25

1) exergonic 2) endergonic based on their free energy (∆G) state

Question 26

Exergonic reaction

Answer 26

proceeds with a net release of free energy and is a spontaneous reaction (- ∆G)

Question 27

Endergonic reaction

Answer 27

one that absorbs free energy from its surroundings and is non spontaneous (+ ∆G)

Question 28

Reactions in a closed system

Answer 28

- eventually reach equilibrium - can perform no work - is a dead cell

Question 29

Reactions in an open system

Answer 29

Cells tend to maintain a state of disequilibrium, which are capable of constantly exchanging matter with their surroundings

Question 30

Coupling Reactions

Answer 30

ATP powers the coupling of exergonic and endergonic reaction as a way to manage their energy resources to do work

Question 31

3 kinds of work a cell does

Answer 31

1) Mechanical 2) Transport 3) Chemical

Question 32

1) Mechanical

Answer 32

the beating of cilia or contraction of muscles

Question 33

2) Transport

Answer 33

the pumping of substances across membranes

Question 34

3) Chemical

Answer 34

driving endergonic reactions such as the synthesis of polymers from monomers

Question 35

ATP (adenosine triphosphate)

Answer 35

the cell's energy shuttle and provides energy for cellular functions

Question 36

Energy released from ATP

Answer 36

when the terminal phosphate bond is broken by hydrolysis and favorable products are produced releases 7.3kcal of energy/mole of ATP with a (- ∆G)

Question 37

ATP hydrolysis can be

Answer 37

coupled to other reactions to make the overall runs favorable of the cell i.e. glutamic acid + ammonia => glutamine (G: +3.4kcal/mol) with ATP + H2O => ADP + P ( G: -7.3kcal/mol) = total G -3.9kcal/mol

Question 38

ATP drives endergonic reactions by

Answer 38

phosphorylation: transferring a phosphate to other molecules creating a more reactive (less stable) than the original unphosphorylated molecule

Question 39

The hydrolysis of ATP powers three types of

Answer 39

cellular work 1) Mechanical: place P on protein=> activate (i.e. myosin); ATP phosphorylates motor proteins 2) Transport: active transport; ATP phosphorylates transport proteins 3) Chemical: coupling or adding P on substrates; ATP phosphorylates key reactants

Question 40

ATP is a renewable resource that

Answer 40

can be regenerated by the addition of a phosphate group to ADP - the energy to phosphorylate ADP comes from various catabolic pathways that drive the regeneration of ATP from ADP and phosphate

Question 41

Enzymes

Answer 41

- speed up metabolic reactions to make them biologically relevant by lowering energy barriers - a catalytic protein capable of speeding up reaction rates by lowering energy barriers (make reactions go faster)

Question 42

Catalyst

Answer 42

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

Question 43

Enzymes regulate

Answer 43

reactions in metabolic pathways by bond breaking and forming "reorganization"

Question 44

Enzymes within a cell may be groups into

Answer 44

complexes, incorporated into membranes, or contained inside organelles (i.e. the mitochondria)

Question 45

Ribosome

Answer 45

is an enzyme made up of protein and RNA

Question 46

Every chemical reaction between molecules involves both

Answer 46

bond breaking and bond forming and enzymes help break and reform chemical bonds

Question 47

Sucrase

Answer 47

an enzyme that catalyzes the hydrolysis of sucrose is a chemical reaction involving the breaking of the bond between glucose and fructose and the formation of new bonds with hydrogen and hydroxyl ions with water

Question 48

Activation Energy (Ea)

Answer 48

the initial amount of energy needed to start a chemical reaction - the energy to push the reactants over the energy barrier

Question 49

At the summit of the reaction, the molecules are in an unstable condition known as

Answer 49

transition state

Question 50

Enzyme and activation energy

Answer 50

an enzyme will catalyze/speed up reactions by lowering Ea barrier but not the ∆G

Question 51

Energy profile or "reaction coordinate" for an exergonic reaction

Answer 51

releases energy into its surrounding

Question 52

Enzymes accelerate

Answer 52

reactions and lower their Ea by providing an environment for the chemical reaction to proceed

Question 53

Substrate

Answer 53

the reactant or molecule an enzyme acts on

Question 54

Enzyme binds to substrate

Answer 54

forming an enzyme-substrate complex during which the catalytic action of the enzyme converts the substrate to the product or products - binds at the active site which is a specific region on the enzyme where the substate binds

Question 55

Induced fit of a substrate

Answer 55

brings chemical groups of the active site into positions that enhance or tighten their ability to catalyze the chemical reaction wth their substrates

Question 56

Active Site can lower Ea barrier by

Answer 56

1) orienting substrates correctly, 2) straining substrate bonds, 3) providing a favorable microenvironment 4) covalently bonding to the substrate

Question 57

the activity of an enzyme is affected by general environment factors

Answer 57

temperature and pH

Question 58

Each enzyme has an optimal temperature and pH in which it can function

Answer 58

i.e. Taq (temperature) | Trypsin (pH 8 , intestinal pH)

Question 59

Cofactors

Answer 59

nonprotein enzyme helpers (inorganic)

Question 60

Coenzymes

Answer 60

organic cofactors for enzymes

Question 61

Competitive inhibitors

Answer 61

bind tot eh active site of an enzyme competing with the substrate

Question 62

Noncompetitive inhibitor

Answer 62

bind to another part of an enzyme, changing the function

Question 63

Metabolic pathways

Answer 63

must be tightly regulated and enzyme activity is essential to control cellular metabolism

Question 64

Allosteric regulation

Answer 64

a protein's function at one site is affected by binding of a regulatory molecule at another site

Question 65

Many enzymes are allosterically regulated

Answer 65

to become more stable (active) or inhibited (stop/block) depending on the needs of the cell

Question 66

Allosteric enzymes

Answer 66

change shape when regulatory molecules bind to specific sites, affecting function

Question 67

Cooperativity

Answer 67

a form of allosteric regulation that can amplify enzyme activity - enzymes with multiple cattail units can become stabilized upon substrate binding which factors additional substrate binding and activity i.e. oxygen binding and transport protein hemoglobin

Question 68

Feedback inhibition

Answer 68

- the end product of metabolic pathway feeds bask upon itself and shuts down the pathway - prevents a cell from wasting chemical energy i.e. Isoleucine will feedback and inhibit threonine deaminase