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Bio 217 > Topic 6 > Flashcards

Topic 6 Flashcards

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Biology 101 flashcards
1
Q

Living cells are

A

miniature chemical factories

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2
Q

Cellular respiration extracts energy stored in

A

sugars and other fuels
* Cells apply this energy to perform work

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3
Q

Metabolism:

A

the sum of all chemical reactions in an organism
* Transforms matter and energy
* Subject to Laws of Thermodynamics

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4
Q

Metabolism is an emergent property of life that arises from

A

orderly interactions between molecules

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5
Q
  • A metabolic pathway begins with
A

a specific molecule and ends with a product
* Each step is catalyzed by a specific enzyme
* Cascade effect drives conversion from A to D

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6
Q

Two types of metabolic pathways

A

Catabolic pathways:
* Release energy by breaking down complex molecules into simpler compounds
* Ie) Cellular respiration, the breakdown of glucose in the presence of oxygen

Anabolic pathways:
* Consume energy to build complex molecules from simpler ones
* Ie) The synthesis of protein from amino acids

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7
Q

Bioenergetics:

A

the study of how energy flows through living organisms

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8
Q
  • Energy:
A
  • Capacity to cause change
  • Exists in various forms, some of which can perform work
    Can be converted from one form to another
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9
Q
  • Types of Energy:
A
  • kinetic
  • thermal
  • potential
  • chemical
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10
Q
  • Kinetic energy:
A

energy associated with motion

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11
Q

thermal energy

A

the kinetic energy associated with random movement of atoms or molecules
heat- thermal enery transferred between objects

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12
Q

potential energy

A

energy that matter possesses becuase of its location or structure

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13
Q

chemical energy

A

potential energy avaliable for release in a chemical reaction

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14
Q

Thermodynamics

A

is the study of energy transformations

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15
Q

Isolated vs open systems:
isolated

A

unable to exchnage energy or matter with its surroundings

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16
Q

open systems

A

able to exchnage energy or matter with surroundings
- organisms are open systems

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17
Q

The First Law of Thermodynamics:

A
  • The principle of conservation of energy
  • The energy of the universe is constant
  • Energy can be transferred and transformed, but it cannot be created or destroyed
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18
Q

The Second Law of Thermodynamics

A
  • During every energy transfer or transformation, some energy is unusable and is often lost as heat
  • Every energy transfer or transformation increases the entropy of the universe
  • Entropy is a measure of molecular disorder, or randomness
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19
Q
  • Entropy
A

a measure of molecular disorder, or randomness

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20
Q

Biological Order vs Disorder 1

A
  • Living cells convert organized forms of energy to heat
  • Heat is a more disordered form of energy
  • But, in Topic 01, Order was a Unifying Theme in Biology
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21
Q

Biological Order vs Disorder 2

A
  • Organisms create ordered structures from less organized forms of energy and matter
  • Organisms also replace ordered forms of matter and energy in their surroundings with less ordered forms
  • Ie) animals consume complex molecules in their food and release smaller, lower energy molecules and heat into the surroundings
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22
Q

Biological Order vs Disorder 3

A
  • The evolution of more complex organisms does not violate the second law of thermodynamics
  • Entropy (disorder) may decrease in a particular system, such as an organism, so long as the total entropy of the system and surroundings increases
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23
Q

Conversion of Energy

A
  • Living cells convert organized forms of energy to heat (a more disordered form of energy)
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24
Q
  • Spontaneous processes:
A
  • occur without energy input
  • can happen quickly or slowly
  • for a proccess to occur spontaneously, it must increase the entropy of the universe
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25
Q

non spontaneous process

A

decrease entropy, need energy to occur

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26
Q
  • Free Energy
A

energy that can do work when temperature and pressure are uniform, as in a living cell
represented as: G
- Free Energy change indicates whether reaction occurs spontaneously or not

27
Q

Free energy is a measure of

A

a system’s instability - its tendency to change to a more stable state
- During a spontaneous change, free energy decreases, and the stability of a system increases

28
Q
  • Equilibrium is a state of
A

maximum stability
* A process is spontaneous and can perform work only when it is moving toward equilibrium

29
Q

exergonic reaction:

A
  • Proceeds with a net release
    of free energy * Spontaneous * G < 0
30
Q

endergonic reaction:

A
  • Absorbs free energy from its
    surroundings
  • Nonspontaneous * G > 0
31
Q

Equilibrium and Metabolism

A

Reactions in a closed system eventually reach equilibrium and can then do no work

32
Q

Cells are not in

A

equilibrium
* A defining feature of life is that
metabolism is never at equilibrium
* A catabolic pathway in a cell releases free energy in a series of reactions

33
Q
  • A cell does 3 main kinds of work:
A

Chemical work: pushing
endergonic reactions
* Transport work: pumping substances against the direction of spontaneous movement
* Mechanical work: such as contraction of muscle cells

34
Q
  • To perform work, cells use
A

energy coupling

35
Q

Energy coupling:

A

the use of exergonic processes to drive endergonic processes
* Most energy coupling in cells is mediated by ATP and ATP hydrolysis

36
Q

ATP Hydrolysis

A
  • Bonds between the phosphate groups of ATP’s tail can be broken by hydrolysis
  • Energy is released from ATP when the terminal phosphate bond is broken
  • This release of energy comes from the chemical change to a state of lower free energy, not from the phosphate bonds themselves
37
Q
  • Cellular work (mechanical, transport, and chemical) is powered by
A

the hydrolysis of ATP

38
Q

Energy from the exergonic reaction of ATP hydrolysis can be used to drive an

A

endergonic reaction

39
Q

ATP drives endergonic reactions by

A

phosphorylation, transferring a phosphate group to some other molecule, such as a reactant
The recipient molecule is now called a phosphorylated intermediate
* Overall, the coupled reactions are exergonic and occur spontaneously

40
Q

Transport and mechanical work in the cell are also powered by

A

ATP hydrolysis
* ATP hydrolysis leads to a change in protein shape and binding ability

41
Q

what needs to be regenerated

A
  • ATP hydrolysis is an exergonic reaction, so it occurs spontaneously
  • ATP levels become depleted and need to be regenerated by adding a phosphate group to adenosine diphosphate (ADP)
42
Q

ATP regeneration

A
  • The energy to phosphorylate ADP comes from catabolic reactions in the cell
  • Ie) cellular respiration, photosynthesis
  • The ATP cycle is a revolving door through which energy passes during its transfer from catabolic to anabolic pathways
43
Q
  • Enzymes are
A

proteins that speed up chemical reactions
* Catalysts:

44
Q
  • Catalysts:
A

they speed up reaction without being consumed
* Often have name that ends in ‘ase’

45
Q

Every chemical reaction between molecules involves

A

bond breaking and bond forming

46
Q

How enzymes speed up reactions

A
  • Enzymes speed up specific reactions by lowering the EA barrier
  • Enzymes do not affect the change in free energy (ΔG)
  • Enzymes allow reactions that would eventually occur to occur faster
47
Q
  • The enzyme binds to its substrate, forming an
A

enzyme-substrate complex
* While bound, the activity of the enzyme converts substrate to product

48
Q
  • The active site is the
A

region on the enzyme where the substrate binds

49
Q
  • Induced fit of a substrate:
A
  • Brings chemical groups of the active site into positions that enhance their ability to catalyze the reaction
  • Lock and Key Model
50
Q
  • Induced fit of a substrate:
A
  • Brings chemical groups of the active site into positions that enhance their ability to catalyze the reaction
  • Lock and Key Model
51
Q
  • Enzymes are:
A
  • Extremely fast acting
  • Catalysts: Emerge from reactions in their original form
  • Very small amounts of enzyme can have huge metabolic effects
  • Used repeatedly in catalytic cycles
52
Q
  • The active site can lower activation energy by 4
A
  • Orienting substrates correctly
  • Straining substrate bonds
  • Providing a favorable microenvironment
  • Covalently bonding to the substrate
53
Q
  • The rate of an enzyme-catalyzed reaction can be sped up by
A

increasing substrate concentration
* When all enzyme molecules have their active sites engaged, the enzyme is saturated
* If the enzyme is saturated, the reaction rate can only be sped up by adding more enzyme

53
Q
  • An enzyme’s activity can be affected by:
A
  • Environmental factors, such as temperature & pH
  • Chemicals tha tspecifically influence the enzyme
  • Each enzyme has optimal temperature and pH for its function
  • Optimal conditions – favor most active shape for enzyme molecule
54
Q
  • Cofactors
A

are non-protein enzyme helpers
* Cofactors may be inorganic (a metal in ionic form) or organic
* An organic cofactor is called a coenzyme
* Coenzymes include vitamins

55
Q
  • Competitive inhibitors:
A
  • Bind to the active site of an enzyme
  • Compete with the substrate
56
Q
  • Noncompetitive inhibitors:
A
  • Bind to another part of an enzyme, causing the enzyme to
    change shape
  • Makes the active sitel ess effective
  • Examples of inhibitors: toxins, poisons, pesticides, and antibiotics
  • Not all inhibitors are bad, allows for regulation of enzymatic activity
57
Q
  • A cell’s metabolic pathways need to be tightly regulated A cell does this by:
A
  • Switching on or off the genes that encode specific enzymes
  • Regulating the activity of enzymes
58
Q

Allosteric regulation:

A
  • May either inhibit or stimulate an enzyme’s activity
  • A regulatory molecule binds to a protein at one site, and affects the protein’s function at another site
59
Q
  • Most allosterically regulated enzymes are made from
A

polypeptide subunits, each with its own active site
* The enzyme complex has active and inactive forms

59
Q
  • The binding of an activator stabilizes
A

the active form of the enzyme

60
Q
  • Cooperativity:
A

a form of allosteric regulation that can amplify enzyme activity
* One substrate molecule primes an enzyme to more easily act on additional substrate molecules
* Cooperativity is allosteric because binding by a substrate to one active site affects catalysis in a different active site

61
Q
  • Feedback inhibition:
A
  • The end-product of a metabolic
    pathway shuts down the pathway
  • Prevents a cell from wasting chemical resources by synthesizing more product than is needed
62
Q
  • Compartmentalization within the cell help bring
A

order to metabolic pathways
* In eukaryotic cells, some enzymes reside in specific organelles
* Ie) Enzymes for cellular respiration are in mitochondria
* Ie) Acid hydrolases in lysosome

Bio 217 (14 decks)

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