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Biology 202 > Chapter 8 > Flashcards

Chapter 8 Flashcards

1
Q

Metabolism

A

totality of an organism’s chemical reactions; an emergent property of life that arises from interactions between molecules within the cell

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2
Q

Metabolic pathway

A

-begins with a specific molecule
-ends with a product
-each step is catalyzed by a specific enzyme

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3
Q

What are the types of metabolic pathways?

A

catabolic and anabolic

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4
Q

Catabolic pathways

A

-release energy by breaking down complex molecules into simpler compounds
EXAMPLE: cellular respiration(the breakdown of glucose in the presence of oxygen)

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5
Q

Anabolic pathways

A

-consume energy to build complex molecules from simpler ones
EXAMPLE: the synthesis of protein from amino acids

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6
Q

What is bioenergetics?

A

the study of how organisms manage their energy resources

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7
Q

What is energy?

A

-the capacity to cause change
-exists in various forms, some of which can perform work-to move matter against opposing forces or rearrange matter

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8
Q

Kinetic energy

A

energy associated with motion
-heat(thermal energy; kinetic energy associated with random movement of atoms or molecules)
-light(photosynthesis)

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9
Q

Potential energy

A

-energy that matter possesses because its location or structure(water behind a dam)
-chemical energy(potential energy available for release in a chemical reaction-glucose; hydrocarbons)

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10
Q

Thermodynamics

A

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

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11
Q

System

A

the matter under study
-everything outside the system is surrounding
-isolated system: does not exchange energy and matter with the surrounding
-open system: exchange E and M; all the organisms are open systems

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12
Q

Principle of Conservation of Energy(first law of thermodynamics)

A

the energy of the universe is constant
-energy cannot be created nor destroyed
-plants do not produce energy they transform light energy to chemical energy

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13
Q

Second law of thermodynamics

A

every energy transfer or transformation increases the entropy (disorder) of the universe

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14
Q

Spontaneous process

A

occurs without energy input; they can happen quickly or slowly
-for a process to occur without energy input, it must increase the entropy of the universe

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15
Q

Non-spontaneous process

A

requires input of energy

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16
Q

How does energy flow into most ecosystems?

A

enters as a form of light and exits in the form of heat to increase entropy

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17
Q

How can we determine which reactions occur spontaneously and which ones require an input of energy?

A

need to determine energy changes that occur in chemical reactions

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18
Q

What is free energy?

A

energy that can do work when temperature and pressure are uniform(G)

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19
Q

Change in free energy

A

delta G= delta H- TdeltaS
(change in free energy= change in enthalpy(equivalent to total energy) - temperature in kelvin(K= C+273)(change in entropy)

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20
Q

Processes with a negative delta G are

A

spontaneous

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21
Q

Processes that have a positive or zero delta G are

A

never spontaneous

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22
Q

The change in the free energy is equivalent to

A

the difference of the free energy in the final state and the free energy in the initial state:
delta G=Gfinal state-Ginitial state
-delta G can be negative only if the final state has less free energy than the initial state
-because of the less free energy the system in its final state is more stable

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23
Q

Free energy=

A

measure of a systems instability, its tendency to change to a more stable state

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24
Q

What happens during a spontaneous change?

A

free energy decreases and stability of a system increases

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25
What is equilibrium?
a state of maximum stability, no further net changes in concentration of product and reactants (G is at its lowest value at the system)
26
Exergonic reaction
proceeds with a net release of free energy and is spontaneous (during respiration 1 mol Glucose releases 686 kcal)
27
Endergonic reaction
absorbs free energy from its surroundings and is non-spontaneous (during photosynthesis plants capture light to get the 686 kcal and to produce 1 mol glucose)
28
True or False: cells are not in equilibrium
True; they are open systems experiencing a constant flow of materials
29
Metabolism
is NEVER at equilibrium
30
What do catabolic pathways do in cells?
release free energy in a series of reactions
31
Closed and open hydroelectric systems
can serve as analogies-for example during respiration the E is released in several steps
32
What are the 3 main kinds of work a cell does?
-chemical(synthesis of polymers) -transport(Na-K pump) -mechanical(segregation of chromosomes)
33
In order for cells to do work, they must manage?
energy resources by energy coupling, the use of an exergonic process to drive an endergonic one -most energy coupling in cells is mediated by ATP
34
What is ATP?
adenosine triphosphate; the cell's energy shuttle; composed of ribose(sugar), adenine(nitrogenous base), & 3 phosphate groups
35
What are the bonds between the phosphate groups of ATP's tail can be broken by?
hydrolysis
36
When the terminal phosphate bond is broken what occurs?
energy is released from ATP
37
Phosphorylation
transferring a phosphate group to some other molecule, such as a reactant: ATP drives endergonic reactions through this
38
Phosphorylated intermediate
the recipient molecule; more reactive(less stable) than the original unphosphorylated molecules
39
What is ATP(not definition)?
a renewable resource that is regenerated by addition of a P group to adenosine diP(ADP)
40
Where does energy to phosphate ADP come from?
catabolic reactions in the cell
41
What does a working muscle cell recycle(use and regenerate)?
10,000,000 molecules of ATP per second per cell
42
Enzyme
a catalytic protein
43
Catalyst
chemical agent that speeds up a reaction without being consumed by the reaction EXAMPLE: hydrolysis of sucrose by the enzyme sucrase
44
Sucrose and water break to from
fructose and glucose
45
Free energy of activation; activation energy (AE)
the initial energy needed to start a chemical reaction -often supplied in the form of thermal energy that the reactant molecules absorb from their surroundings
46
How do enzymes catalyze reactions?
by lowering the activation energy barrier
47
What determines which chemical processes will occur at any given time?
enzymes
48
True or False: enzymes affect change in free energy (delta G)
False
49
Enzyme's substrate
reactant that enzyme acts on
50
Enzyme-substrate complex
enzyme binds to its substrate
51
What is the active site?
region on enzyme where substrate binds
52
What is the induced fit of a substrate?
brings chemical groups of active site into positions that enhance their ability to catalyze reaction
53
How can an active site lower an activation energy barrier?
-orienting substrates correctly -straining substrate bonds -providing a favorable microenvironment -covalently bonding to the substrate
54
How can an enzyme's activity be affected?
-general environmental factors(temperature and pH)*optimal conditions favor the most active shape for the enzyme -chemicals(nonprotein helpers called cofactors)
55
What do cofactors do?
bind permanently or reversibly to the enzyme
56
What are examples of inorganic cofactors?
zinc, iron, copper
57
Organic cofactors
coenzymes (vitamins)
58
Types of enzyme inhibitors
-reversible and irreversible inhibitors -competitive inhibitors(bind to active site of enzyme, complete with substrate) -noncompetitive inhibitors (binds to another part of enzyme, causing enzyme to change shape and make active site less effective EXAMPLE: toxins, poisons, pesticides, antibiotics
59
Changes in genes lead to
changes in amino acid composition of an enzyme; may alter their substrate specificity
60
b-Galactosidase breaks lactose into
Glu + Gal
61
What would result if a cell's metabolic pathways were not tightly regulated?
chemical chaos
62
How does a cell tightly regulate metabolic pathways?
-switching on or off the genes that encode specific enzymes -regulating the activity of enzymes
63
When does allosteric regulation occur?
when a regulatory molecule binds to a protein at one site and affects the proteins function at another site; may either inhibit or stimulate an enzymes activity
64
Most allosterically regulated enzymes are made from
polypeptide subunits
65
The active form of an enzyme is stabilized by
the binding of an activator (ADP for catabolic enzymes)
66
The inactive form of an enzyme is stabilized by
the binding of an inhibitor (ATP for catabolic enzymes)
67
What is cooperativity?
-a form of allosteric regulation that can amplify enzyme activity -one substrate molecule primes an enzyme to act on additional substrate molecules more readily -allosteric because binding by a substrate to one active site affects catalysis in a different active site
68
Caspases
inhibition of proteolytic enzymes; may help management of inappropriate inflammatory responses
69
Allosteric regulators
attractive drug candidates for enzyme regulation
70
What does the end product of a metabolic pathway do?
-shuts down the pathway -prevents cell from wasting chemical resources by synthesizing more product than needed
71
Some enzymes
act as structural components of membranes; in eukaryotic cells, some enzymes reside in specific organelles EXAMPLE: enzymes for cellular respiration are located in the mitochondria

Biology 202 (5 decks)

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