slide 8

Question 1

Metabolism

Answer 1

The Energy of Life

Question 2

The living cell

Answer 2

• Is a miniature factory where thousands of
reactions occur
• Converts energy in many ways

Question 3

Metabolism

Answer 3

• Includes all of an organism’s chemical reactions
• Is a network of pathways
• Arises from interactions between molecules

Question 4

An organism’s metabolism transforms

Answer 4

matter and

energy subject to the laws of thermodynamics

Question 5

A metabolic pathway has many steps
These begin with a specific molecule or
molecules and end with a specific product

Answer 5

Each step is facilitated by a specific catalyst

Question 6

A catalyst

Answer 6

is a substance that
accelerates the rate of a
chemical reaction without
affecting the products of the
reaction and without itself
being altered or consumed by
the reaction.

Question 7

enzymes.

Answer 7

The catalysts in living
organisms are proteins called
enzymes

Question 8

Metabolic pathways balance supply and demand.

Answer 8

• Speed up reactions when not enough product is present
• Slow down reactions when a surplus of product is present
• Products in one set of reactions are the starting molecules
in other sets of reactions.

Question 9

Catabolic pathways

Answer 9

• Break complex molecules into simpler ones
• Release energy
e.g. hydrolysis
reactions

Question 10

Anabolic pathways

Answer 10

• Build complicated molecules from simpler ones
• Consume energy
e.g. dehydration
reactions

Question 11

Energy

Answer 11

– Is the capacity to cause change

– Exists in various forms, some can perform work

Question 12

Kinetic energy

Answer 12

– Is the energy associated with motion

Question 13

Potential energy

Answer 13

– Is stored in the location of matter
– Includes chemical energy stored in molecular
structure (chemical bonds)

Question 14

There are many forms of energy
(light, heat, chemical, electrical,
etc.) but only two states:

Answer 14

Potential energy is stored energy

Kinetic energy is the energy
present in the motion of a body

Question 15

1st law of thermodynamics

Answer 15

• energy is neither
  created or destroyed, but can be transformed
  from one form to another

Question 16

2nd law of thermodynamics -

Answer 16

physical systems
tend to proceed to a state of greater disorder
(entropy)

Question 17

Energy enters a biological system

Answer 17

is spent, transformed, and lost as heat.

Question 18

Gibbs free energy is the energy available for

work in a system at uniform temperature.

Answer 18

Josiah Willard Gibbs

1839-1903

Question 19

The free-energy change of a reaction tells us

whether the reaction occurs spontaneously.

Answer 19

During a spontaneous change free energy

decreases and the stability of a system increases

Question 20

Spontaneous change:

Answer 20

- The free energy of the system
decreases
- The system becomes more stable
- The released free energy can be
harnessed to do work

Question 21

exergonic reactions.

Answer 21

The majority of the reactions in living cells release

free energy and are called exergonic reactions.

Question 22

endergonic reactions.

Answer 22

Many important reactions in cells, however,
require the addition of energy and are called
endergonic reactions

Question 23

equilibrium,

Answer 23

Reactions in a closed system eventually reach

equilibrium, and can do no more work.

Question 24

Equilibrium and Metabolism

Answer 24

Cells in our body
experience a constant flow
of materials in and out,
preventing metabolic
pathways from reaching
equilibrium

Question 25

Cellular metabolism

Answer 25

is an open, multi-step process

Question 26

Entropy (disorder)

Answer 26

is decreased in living organisms
by metabolic processes, but this results in increased
entropy of the larger system.

Question 27

Entropy (disorder)

Answer 27

is decreased in living organisms
by metabolic processes, but this results in increased
entropy of the larger system.

Question 28

• Just because a reaction is exergonic, and therefore

occurs spontaneously, does not mean it occurs rapidly.

Answer 28

• Even exergonic reactions require destabilization of

chemical bonds through the input of activation energy

Question 29

Enzymes catalyze

Answer 29

reactions

by lowering the EA barrier

Question 30

enzyme’s substrate.

Answer 30

The reactant that an enzyme acts on is

called the enzyme’s substrate.

Question 31

enzyme-substrate complex

Answer 31

The enzyme binds to its substrate, forming

an enzyme-substrate complex.

Question 32

The active site

Answer 32

is the region on the enzyme

where the substrate binds

Question 33

The active site can lower an EA barrier by

Answer 33

• Orienting substrates correctly
• Straining substrate bonds
• Providing a favorable microenvironment
• Covalently bonding to the substrate

Question 34

Each enzyme has an optimal temperature

in which it can function properly

Answer 34

Each enzyme has an optimal pH

in which it can function properly

Question 35

Cofactors

Answer 35

are nonprotein enzyme helpers

Question 36

Cofactors may be

Answer 36

inorganic (such as a metal

in ionic form) or organic

Question 37

coenzyme

Answer 37

An organic cofactor is called a coenzyme

Coenzymes include vitamins.

Question 38

Competitive inhibitors

Answer 38

bind to the active site of

an enzyme, competing with the substrate.

Question 39

Noncompetitive inhibitors

Answer 39

bind to another part
of an enzyme, causing the enzyme to change
shape and making the active site less effective.

Question 40

Allosteric regulation

Answer 40

occurs when a regulatory
molecule binds to a protein at one site and affects
the protein’s function at another site.

Question 41

Metabolism can be regulated by switching

Answer 41

on or
off the genes that encode specific enzymes or by
regulating the activity of enzymes

Question 42

Cooperativity

Answer 42

is a form of allosteric regulation

that can amplify enzyme activity

Question 43

Cooperativity

Answer 43

is a form of allosteric regulation

that can amplify enzyme activity

Question 44

One substrate molecule primes

Answer 44

an enzyme to act

on additional substrate molecules more readily.

Question 45

Allosteric regulators are attractive drug
candidates for enzyme regulation because of
their specificity

Answer 45

Inhibition of proteolytic enzymes called caspases
may help management of inappropriate
inflammatory responses

Question 46

In feedback inhibition,

Answer 46

the end product of a

metabolic pathway shuts down the pathway

Question 47

Feedback inhibition prevents a cell from wasting

Answer 47

chemical resources by synthesizing more product

than is needed

Question 48

Location of Enzymes

Answer 48

Structures within the cell help bring

order to metabolic pathways.

Question 49

Some enzymes act as structural

components of membranes

Answer 49

In eukaryotic cells, some enzymes

reside in specific organelles.

Question 50

Changes (mutations) in genes lead to changes

in amino acid composition of an enzyme

Answer 50

Altered amino acids in enzymes may alter their

substrate specificity

Question 51

Lab experiments have been successful in

altering the function

Answer 51

of β–galactosidase from

the bacterium E. coli.