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Bio 122 > Exam 2 > Flashcards

Exam 2 Flashcards

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Biology 101 flashcards
1
Q

Metabolism

A

totality of organism’s chemical reactions

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2
Q

catabolic pathways

A

reactions that release energy by breaking down complex molecules to simpler compounds

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3
Q

anabolic pathways

A

consume energy to build complicated molecules from simpler compounds

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4
Q

kinetic energy

A

-energy of motion
-heat

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5
Q

potential energy

A

-capacity to do work
-chemical energy- stored in chemical bonds

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6
Q

thermodynamics

A

-the study of the transformation of energy

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7
Q

1st Law of Thermodynamics

A

-energy can be transferred and transformed, it cannot be created or destroyed

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8
Q

2nd Law of Thermodynamics

A

-every energy transfer or transformation must increase disorder/entropy in the universe

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9
Q

Entropy

A

measure of disorder or randomness

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10
Q

free energy (G)

A

portion of a systems energy that can perform work when temp and pressure are constant

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11
Q

what state do systems spontaneously move towards?

A

lower free energy state (where ΔG is negative)

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12
Q

Spontaneous

A

-will occur without an input of energy
-does not infer anything regarding the speed of the process

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13
Q

exergonic reaction

A

-releases free energy
-ΔG is negative

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14
Q

endergonic reaction

A

-absorbs free energy from environment and stores in molecules
-ΔG is positive

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15
Q

example of exergonic rxn

A

-hydrolysis of sucrose
-glucose metabolism

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16
Q

example of endergonic rxn

A

-sucrose synthesis
-gluconeogenesis

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17
Q

what does ATP stand for?

A

adenosine triphosphate

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18
Q

ATP

A

-energy is released from bonds between phosphate groups
-exergonic reaction
(ΔG= -7.3 kcal/mol)

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19
Q

energy coupling

A

-the use of an exergonic rxn to drive an endergonic rxn
-hydrolysis of ATP is used as the exergonic rxn

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20
Q

activation energy

A

-transition state!
-chemical rxns between molecules involve both bond breaking and bond formation
-initial investment of energy to initiate rxn

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21
Q

what happens after the application of activation energy?

A
  1. chemical bonds rearrange
  2. unstable intermediates are formed (transition state)
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22
Q

enzymes catalyze what?

A

catalyze the conversion of substrate to product

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23
Q

substrate

A

a reactant that binds to an enzyme

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24
Q

how do enzymes promote chemical rxn?

A

-they reduce the activation energy
they cannot change ΔG of rxn though

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25
Q

where do substrates bind on an enzyme?

A

the active site

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26
Q

enzyme specificity

A

the fit between the active site and the substrate
think of puzzle piece

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27
Q

what catalyzes enzymatic reaction?

A

R-groups of a few amino acids in the active site

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28
Q

how many rxns per second can a single enzyme molecule catalyze?

A

thousands

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29
Q

are enzymes affected in any way by the reaction?

A

No, they are unaffected and reusable

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30
Q

what determines if metabolic enzymes catalyze a rxn in the forward or reverse direction?

A

it all depends on the ΔG

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31
Q

Factors that affect enzyme activity (5)

A
  1. substrate concentration
  2. temperature
  3. pH
  4. cofactors
  5. inhibitors
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32
Q

substrate concentration

A
  • the more substrate available, the more frequently it makes contact with the active site (this increases the rxn rate)

-at a very high substrate concentration, enzyme becomes saturated
*active sites on all enzymes are engaged
*to increase activity of a saturated enzyme, you need to increase the amount of enzyme

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33
Q

temperature (in relation to enzyme activity)

A

-higher temperatures increase collisions between substrates and active site of enzymes (increase enzyme activity)

-at too high of a temperature, the bonds that stabilize the enzyme’s active site are destabilized (the enzyme denatures)

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34
Q

pH (in relation to enzyme activity)

A

-influences enzyme shapes and rxn rate
-each enzyme has an optimal pH (it’s 6-8 for most, EXCEPT digestive enzymes)

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35
Q

cofactors

A

-nonprotein helpers
-bind to enzyme (often the active site) and facilitate enzymatic rxn
-inorganic ions *zinc *copper
-organic molecules *coenzymes *vitamins

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36
Q

inhibitors

A

-compounds that reduce enzyme activity
-competitive and noncompetitive inhibitors

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37
Q

competitive inhibitor

A

-molecule that mimics true substrate
-blocks active site

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38
Q

non-competitive inhibitor

A

-a molecule that binds to the enzyme away from the active site and alters the shape of the active site

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39
Q

feedback inhibition

A

-end product of a pathway acts as an inhibitor of enzymes in the pathway
-when the product’s abundant the path is turned off, when product is rare the pathway is active

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40
Q

cellular respiration overall equation

A

organic compounds + O2
–> CO2 +H2O + energy

41
Q

cellular resp. equation glucose

A

C6H12O6 + 6O2
–> 6CO2 + 6H2O + (ATP & heat energy)

42
Q

Redox reactions

A

-catabolic pathways relocate e- stored in food molecules release energy and ATP
-transfer of e- in simple terms

43
Q

reducing agent is what?

A

electron donor

44
Q

oxidizing agent is what?

A

electron acceptor

45
Q

can redox rxns occur when e- movement from atom to atom is incomplete?

A

yes!

-example is methane combustion

46
Q

how are polar covalent bonds converted during redox?

A

less polar to more polar

47
Q

what is one of the most potent oxidizing agents? and quite electronegative?

A

oxygen

48
Q

what happens to e- as they shift towards a more electronegative atom?

A

the e- lose energy

49
Q

what happens to the electrons in a redox rxn that moves electrons closer to oxygen?

A

the electrons are released

this E can be harnessed to do work!

50
Q

How do you pull an electron away from a more electronegative atom?

A

add energy to a covalent bond

51
Q

why are molecules that have less polar or nonpolar covalent bonds excellent metabolic fuels?

A

these bonds are a source of electrons that can be pulled towards oxygen

52
Q

example of less polar bonds

A

carbohydrates

53
Q

example of non-polar hydrocarbon bonds

A

fats

54
Q

what does the transfer of all hydrogen electrons to oxygen results in what?

A

a massive release of energy and an explosion

55
Q

electrons are stripped from metabolites and passed to what?

A

a coenzyme electron carrier

56
Q

most common coenzyme electron carrier

A

-NAD+
-nicotinamide adenine dinucleotide

57
Q

dehydrogenase enzymes

A

-strip 2 hydrogen atoms from a molecule
-pass the electrons and one protons to an to an electron acceptor/carrier
-release H+ and a reduced electron carrier such as NADH

58
Q

What functions as an oxidizing agent for
many of the redox steps of glucose catabolism?

A

NAD+

59
Q

3 stages of respiration

A
  1. glycolysis
  2. citric acid cycle/krebs cycle
  3. electron transport chain
60
Q

where does glycolysis occur?

A

cytosol

61
Q

glycolysis

A

-breaks glucose into 2 pyruvate molecules (one 6 carbon sugar into two 3 carbon compounds)
-10 steps- each catalyzed by enzyme
-2 phases- energy investment phase & energy payoff phase

62
Q

Energy investment phase

A

-6 carbon sugar broken into two 3 carbon sugars
-glucose is phosphorylated

63
Q

net yield from glycolysis?

A

2 ATP and 2 NADH per glucose

64
Q

what happens if oxygen happens to be present during glycolysis?

A

pyruvate moves to the Krebs Cycle

65
Q

Krebs Cycle

A

-a multienzyme complex modifies pyruvate to acetyl CoA
-a carboxyl group is removed as CO2
-2 electrons are transferred to NAD+ to form NADH
-pyruvate is oxidized to acetate
-acetate combines with coenzyme A to form acetyl CoA

66
Q

how much available free energy in glucose remains in pyruvate following glycolysis?

A

more than 75%

67
Q

where does the pyruvate go to begin the krebs cycle?

A

the mitochondrion

68
Q

Main process of the krebs cycle (4)

A
  1. rearrangement of carbon skeletons
  2. shuttling of electrons via redox
  3. elimination of fully oxidized carbons as carbon dioxide
  4. ATP production using substrate level phosphorylation
69
Q

krebs cycle produces what?

A
  • 1 ATP
  • 3 NADH
  • 1 FADH2
  • 2 CO2 as waste
70
Q

how many ATP produced by aerobic respiration are from the substrate level phosphorylation

A

only 4 ATP

71
Q

what produces most ATP from aerobic respiration?

A

electron transport chain

72
Q

Electron transport chain

A

-electrons lose free energy as they pass down the chain towards oxygen
-NADH electrons are transferred to the first molecule in the chain
-FADH2 electrons enter later in the chain less E

73
Q

is ATP generated directly or indirectly in electron transport chain?

A

-indirectly using chemiosmosis and the ATP synthase enzyme

74
Q

chemiosmosis

A

-energy coupling mechanism
-use energy stored in the form of a chemical gradient to drive cellular work

75
Q

prokaryotes generate H+ gradients across their cell membrane in order to…? 3

A
  1. used to generate ATP- bacterial ATP synthase
  2. used to pump nutrients and waste products across membrane
  3. used to rotate flagella
76
Q

aerobic respiration

A

-NADH transfers electrons from glycolysis to the e- transport chain
-NAD+ is regenerated and recycled for use as an e- acceptor

77
Q

anaerobic respiration

A

-fermentation pathways generate ATP via glycolysis
-NADH has nowhere to go *b/c no e- transport chain
-NAD+ is regenerated by transferring e- from NADH to pyruvate

78
Q

alcohol fermentation

A

-pyruvate is converted to acetaldehyde by removal of CO2
-acetaldehyde is reduced by NADH to ethanol
-used in brewing!

79
Q

lactic acid fermentation

A

-pyruvate reduced directly by NADH to lactate
-used to make cheese/yogurt

OR

-muscle cells switch to lactic acid fermentation when oxygen is scarce

80
Q

facultative anaerobe

A

-cell that can survive using fermentation or respiration
-human muscle cells are facultative

81
Q

phosphofructokinase

A

-key glycolytic enzyme
-inhibited by ATP
-stimulated by AMP (which is a derivative of ADP)

82
Q

photosynthesis

A

process used to convert light energy to chemical energy

83
Q

chloroplast

A

site of photosynthesis
-primarily found in leaves
-contain chlorophyll absorbs light energy

84
Q

chloroplast structural elements

A

-triple membrane
-central aqueous space- stroma
-membranous sacs- thylakoids
-stacks of thylakoids- granas

85
Q

steps of photosynthesis (2)

A

1.light rxns
2.calvin cycle

86
Q

light reactions

A

-convert solar energy to chemical energy
-occurs in thylakoids
-creates ATP using phosphorylation

87
Q

calvin cycle

A

-occurs in the stroma
-incorporates CO2 into an organic compound
-reduces organic compound to a sugar using the NADPH and ATP from the light rxns

88
Q

electromagnetic radiation

A

-has properties of both a wave and a particle
-composed of photons
-ex. visible light

89
Q

a leaf absorbs what colors? and reflects what?

A

absorbs red and blue, reflects green

90
Q

what is the dominant pigment in chloroplast?

A

chlorophyll A

91
Q

chlorophyll A absorbs what best?

A

red and violet-blue wavelengths

92
Q

what do chlorophyll b and carotenoids do?

A

-transfer energy
-they are accessory pigments

93
Q

action spectrum

A

measures changes in photosynthetic activity at different wavelengths
-accessory pigments broaden range

94
Q

what can happen when an atom absorbs a photon?

A

-one of the atom’s electrons is elevated to a higher level with more potential energy

or

-electron moves to an excited state

95
Q

photons are absorbed by photosystems where?

A

in the thylakoid membranes of the chloroplasts

96
Q

photosystem

A

-a complex of chlorophyll and accessory pigments, other proteins, and organic molecules
-acts like a light gathering satellite

97
Q

2 types of photosystems

A

photosystem I- P700 rxn center

photosystem II- P680 rxn center

-work together to capture light energy for ATP and NADPH synthesis

98
Q

linear electron flow

A

-photosystem II absorbs a photon and excites an electron
-energy bounces from pigment to pigment until it reaches the rxn center
-the primary electron acceptor captures an excited electron from rxn center

Bio 122 (4 decks)

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