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Biology 202 > Chapter 8 > Flashcards

Chapter 8 Flashcards

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AP® Biology flashcards Biology 101 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
Q

What is equilibrium?

A

a state of maximum stability, no further net changes in concentration of product and reactants (G is at its lowest value at the system)

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26
Q

Exergonic reaction

A

proceeds with a net release of free energy and is spontaneous (during respiration 1 mol Glucose releases 686 kcal)

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27
Q

Endergonic reaction

A

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)

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28
Q

True or False: cells are not in equilibrium

A

True; they are open systems experiencing a constant flow of materials

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29
Q

Metabolism

A

is NEVER at equilibrium

30
Q

What do catabolic pathways do in cells?

A

release free energy in a series of reactions

31
Q

Closed and open hydroelectric systems

A

can serve as analogies-for example during respiration the E is released in several steps

32
Q

What are the 3 main kinds of work a cell does?

A

-chemical(synthesis of polymers)
-transport(Na-K pump)
-mechanical(segregation of chromosomes)

33
Q

In order for cells to do work, they must manage?

A

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
Q

What is ATP?

A

adenosine triphosphate; the cell’s energy shuttle; composed of ribose(sugar), adenine(nitrogenous base), & 3 phosphate groups

35
Q

What are the bonds between the phosphate groups of ATP’s tail can be broken by?

A

hydrolysis

36
Q

When the terminal phosphate bond is broken what occurs?

A

energy is released from ATP

37
Q

Phosphorylation

A

transferring a phosphate group to some other molecule, such as a reactant: ATP drives endergonic reactions through this

38
Q

Phosphorylated intermediate

A

the recipient molecule; more reactive(less stable) than the original unphosphorylated molecules

39
Q

What is ATP(not definition)?

A

a renewable resource that is regenerated by addition of a P group to adenosine diP(ADP)

40
Q

Where does energy to phosphate ADP come from?

A

catabolic reactions in the cell

41
Q

What does a working muscle cell recycle(use and regenerate)?

A

10,000,000 molecules of ATP per second per cell

42
Q

Enzyme

A

a catalytic protein

43
Q

Catalyst

A

chemical agent that speeds up a reaction without being consumed by the reaction
EXAMPLE: hydrolysis of sucrose by the enzyme sucrase

44
Q

Sucrose and water break to from

A

fructose and glucose

45
Q

Free energy of activation; activation energy (AE)

A

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
Q

How do enzymes catalyze reactions?

A

by lowering the activation energy barrier

47
Q

What determines which chemical processes will occur at any given time?

A

enzymes

48
Q

True or False: enzymes affect change in free energy (delta G)

A

False

49
Q

Enzyme’s substrate

A

reactant that enzyme acts on

50
Q

Enzyme-substrate complex

A

enzyme binds to its substrate

51
Q

What is the active site?

A

region on enzyme where substrate binds

52
Q

What is the induced fit of a substrate?

A

brings chemical groups of active site into positions that enhance their ability to catalyze reaction

53
Q

How can an active site lower an activation energy barrier?

A

-orienting substrates correctly
-straining substrate bonds
-providing a favorable microenvironment
-covalently bonding to the substrate

54
Q

How can an enzyme’s activity be affected?

A

-general environmental factors(temperature and pH)*optimal conditions favor the most active shape for the enzyme
-chemicals(nonprotein helpers called cofactors)

55
Q

What do cofactors do?

A

bind permanently or reversibly to the enzyme

56
Q

What are examples of inorganic cofactors?

A

zinc, iron, copper

57
Q

Organic cofactors

A

coenzymes (vitamins)

58
Q

Types of enzyme inhibitors

A

-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
Q

Changes in genes lead to

A

changes in amino acid composition of an enzyme; may alter their substrate specificity

60
Q

b-Galactosidase breaks lactose into

A

Glu + Gal

61
Q

What would result if a cell’s metabolic pathways were not tightly regulated?

A

chemical chaos

62
Q

How does a cell tightly regulate metabolic pathways?

A

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

63
Q

When does allosteric regulation occur?

A

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
Q

Most allosterically regulated enzymes are made from

A

polypeptide subunits

65
Q

The active form of an enzyme is stabilized by

A

the binding of an activator (ADP for catabolic enzymes)

66
Q

The inactive form of an enzyme is stabilized by

A

the binding of an inhibitor (ATP for catabolic enzymes)

67
Q

What is cooperativity?

A

-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
Q

Caspases

A

inhibition of proteolytic enzymes; may help management of inappropriate inflammatory responses

69
Q

Allosteric regulators

A

attractive drug candidates for enzyme regulation

70
Q

What does the end product of a metabolic pathway do?

A

-shuts down the pathway
-prevents cell from wasting chemical resources by synthesizing more product than needed

71
Q

Some enzymes

A

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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