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BIOL1115 LECTURE > Chapter 8,9 > Flashcards

Chapter 8,9 Flashcards

1
Q

what is metabolism?

A

all of the reactions that build up and break down organic molecules in an organism

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2
Q

what is major form of chemical energy used by cells?

A

ATP

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3
Q

what is catabolism?

A

breakdown of molecules into smaller units

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4
Q

what is anabolism?

A

building of molecules from smaller units

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5
Q

what kind of metabolism requires ATP?

A

the building up of molecules by forming chemical bonds requires energy in anabolism

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6
Q

what kind of metabolism produces ATP?

A

the breakdown of molecules and breaking of chemical bonds supplies enough energy for the anabolic reaction of ATP synthesis to occur

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7
Q

what is energy?

A

the capacity to cause change or do work

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8
Q

what are two major types of energy?

A

kinetic and potential energy

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9
Q

what does potential energy depend on?

A

structure of object and/or position within its surroundings

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10
Q

what do the bonds linking phosphate groups in ATP have?

A

high chemical potential energy

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11
Q

why does the cell not breakdown ADP into AMP further?

A

the second phosphate group is more difficult to remove and requires more energy to break the bond.

energetically unfavourable

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12
Q

what type of energy is present in molecular covalent bonds?

A

chemical potential energy

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13
Q

what is the first law of thermodynamics?

A

energy is conserved - it cannot be created or destroyed

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14
Q

what is the second law of thermodynamics?

A

energy transformations always result in an increase in disorder/entropy in the universe

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15
Q

why are energy transformations never 100% efficient?

A

some energy is lost, usually in the form of heat. energy available to do work decreases

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16
Q

what is Gibbs free energy?

A

amount of energy in a system available to do work

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17
Q

what is ΔG?

A

ΔG = Gp - Gr

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18
Q

what are exergonic reactions?

A

-ΔG release energy, releases energy

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19
Q

what are endergonic reactions?

A

+ΔG release energy, absorbs energy

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20
Q

how is a reaction spontaneous?

A

the reaction is energetically favourable and happens on its own

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21
Q

why are catabolic reactions exergonic?

A

products have less chemical energy, meaning ΔG is negative, products are more disordered/ have more entropy

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22
Q

why are anabolic reactions endergonic?

A

products have more chemical energy, meaning ΔG is positive. products are less disordered/have less entropy

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23
Q

what kind of reaction is ATP hydrolysis?

A

exergonic, spontaneous, catabolic

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24
Q

how can energetic coupling drive nonspontaneous reactions?

A

a spontaneous reaction can drive a nonspontaneous reaction to occur by providing it with energy, making overall reaction thermodynamically favourable

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25
Q

what is an example of energetic coupling?

A

ATP drives nonspontaneous reactions such as synthesis of a macromolecule from smaller units

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26
Q

how do enzymes speed up chemical reactions?

A

enzymes lower activation energy and stabilizing transition state

enzymes also bind to multiple reactants and keep them in close proximity, allowing them to interact

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27
Q

what is a transition state?

A

unstable state in which old bonds are breaking and new ones are forming, therefore having large amount of free energy

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28
Q

what is activation energy?

A

an input of energy that every reactant requires to reach transition state

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29
Q

how do enzymes determine whether or not a reaction goes forward or backward?

A
  • Following the equilibrium constant and the relative concentrations of reactants and products.
  • Coupling the reaction with another reaction that is energetically favorable.
  • Regulating their own activity or expression by various mechanisms.
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30
Q

what is an enzyme’s active site?

A

part of enzyme that binds substrate and converts it to the product

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31
Q

what does the active site do?

A

active site brings substrates into close proximity in correct orientation, interactions btwn active site and substrates help to stabilize transition state and lower activation energy required for reaction

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32
Q

what are catalytic amino acids?

A

amino acids that when protein is folded properly, forms the active site

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33
Q

what are cofactors and coenzymes?

A

nonprotein helpers which bind to proteins and function in catalysis by activating protein/enzyme, allowing it to perform its function

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34
Q

what are cofactors?

A

inorganic ions such as iron zinc copper etc.

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35
Q

what are coenzymes?

A

organic molecules such as vitamins

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36
Q

what is an enzyme inhibitor?

A

chemical that decreases enzyme’s activity

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37
Q

what is competitive inhibition?

A

inhibitor binds to active site

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38
Q

what is non-competitive inhibition?

A

binding sites of inhibitors and substrates are different, binding of a non-competitive inhibitor causes decrease in rate at which enzyme converts substrate to product by changing shape of enzyme

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39
Q

which type of inhibition is usually non-reversible?

A

non-competitive inhibition

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40
Q

what are metabolic pathways?

A

chemical reactions that are organized in a way in which a molecule is altered in a series of steps, each catalyzed by a specific enzyme, to form a final product

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41
Q

what is feedback inhibition?

A

a product may act as an inhibitor for one of the enzymes earlier in the pathway, blocking its own production

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42
Q

what is the advantage of using a feedback inhibition system to a cell?

A

prevents waste and overproduction, the starting material is not wasted

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43
Q

what is an allosteric enzyme?

A

type of enzyme that is activated or inhibited when binding to another molecule causing its shape to change

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44
Q

what is cellular respiration?

A

metabolic pathway converting energy stored in organic fuel molecules

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45
Q

what is overall energy yield of one glucose molecule?

A

around 30 ATP

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46
Q

what happens to the carbons in glucose?

A

become oxidized into CO₂

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47
Q

are fuel molecules COMPLETELY broken down in glycolysis and pyruvate oxidation (step 1 and 2)?

A

NO, partially broken down

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48
Q

are fuel molecules COMPLETELY broken down in the citric acid cycle?

A

YES, completely broken down into CO₂

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49
Q

why do oxidation and reduction reactions always occur together?

A

when a substance loses electrons, another substance must gain those electrons

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50
Q

what are oxidizing agents?

A

electron acceptors, become reduced

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51
Q

what are reducing agents?

A

electron donors, become oxidized

52
Q

do redox reactions always occur with electron transferring?

A

NO, redox reactions can also involve a change in the degree of electron sharing between atoms

53
Q

why is oxygen a good oxidizing agent?

A

it is very electronegative

54
Q

how does an electron lose potential energy?

A

when it shifts from a less electronegative atom to a more electronegative one

55
Q

why does methane have more potential energy than carbon dioxide?

A

methane has less electronegative atoms compared to CO₂, which has oxygen, a very electronegative atom

56
Q

what are the electron carriers in cellular respiration?

A

NAD+ and FAD
(nicotinamide adenine dinucleotide and flavin adenine dinucleotide)

57
Q

what is the purpose of hydrogen anions in cellular respiration?

A

represents electrons, used as electron carriers because electrons cannot be transferred by themselves

58
Q

how do you extract energy from molecules?

A

you oxidize them

59
Q

why are carbon atoms in glucose oxidized in cellular respiration?

A

carbon atoms in glucose share their electrons equally with other atoms

electrons are NOT shared equally in CO₂, carbon does not attract electrons as strongly as oxygen does, meaning carbon atoms partially LOST electrons to oxygen and OXIDIZED

60
Q

why are oxygen atoms in water reduced in cellular respiration?

A

O atoms in O₂ share electrons equally

electrons are NOT shared equally in H₂O, oxygen attracts electrons from H more, meaning oxygen atoms have partially GAINED electrons and is REDUCED

61
Q

what does it mean when an atom has partially gained electrons?

A

atom attracts electrons from other atom in the bond, gaining the electrons in a way, meaning it is reduced

62
Q

what does it mean when an atom has partially lost electrons?

A

atom does not attract electron as strongly as the other atom in the bond, losing the electrons in a way, meaning it is oxidized

63
Q

how does NAD+ accept electrons from glucose?

A

enzyme dehydrogenase removes a pair of hydrogen atoms (represents electrons) from glucose, oxidizing it

hydrogen atoms are transferred to NAD+, reducing it to NADH because it gained the electrons

64
Q

what is the definition of glycolysis?

A

“splitting of sugar” , breaking down 6-carbon glucose into TWO (2) molecules of 3-carbon pyruvate

65
Q

is glycolysis aerobic?

A

NO, glycolysis does not have O₂ as a reactant, meaning the process can occur in the absence of oxygen.

66
Q

where does glycolysis occur?

A

in the cytosol of the cytoplasm

67
Q

what are the three phases of glycolysis?

A

the preparatory phase, steps 1 -3
the cleavage phase, steps 4 - 5
the payoff phase, steps 6 - 10

68
Q

what is the net yield of energy in glycolysis?

A

2 ATP, 2 NADH, 2 Pyruvat

69
Q

what occurs in the prep phase of glycolysis?

A

glucose is prepared by adding 2 phosphate groups, producing fructose 1,6-bisphosphate, needing 2 ATP

70
Q

what occurs in the cleavage phase of glycolysis?

A

fructose 1,6-bisphosphate is split into two molecules of glyceraldehyde 3-phsphate

71
Q

what occurs in the payoff phase of glycolysis?

A

enzyme transfers a phosphate group from phosphoenolpyruvate into ADP, producing ATP and pyruvate.

Four ATP, two pyruvate molecules and two NADH molecules are formed

72
Q

what is substrate-level phosphorylation?

A

enzyme transfers a phosphate group from an organic molecule containing a phosphate molecule to ADP, producing ATP

energetic coupling, using energy from a catabolism reaction to drive the reaction of an anabolism reaction

73
Q

is glucose the only sugar that can contribute to glycolysis?

A

NO, other sugars can be converted into glycolysis intermediates that come later in the pathway

(e.g. fructose receives a phosphate group to form fructose 6-phosphate which enters glycolysis at step 3)

74
Q

what happens to carbons from glucose in glycolysis?

A

oxidized into pyruvate

75
Q

what happened to electrons from glucose?

A

transferred into ATP and NADH

76
Q

why does the inner membrane have so much folds?

A

to maximize surface area for more reactions to occur

77
Q

what is pyruvate oxidation? what occurs during pyruvate oxidation?

A

pyruvate is transported into mitochondrial matrix and oxidizes into an acetyl group and CO₂,

acetyl group transferred to coenzyme A, forming into Acetyl-CoA

78
Q

what is net energy yield in pyruvate oxidation?

A

2 CO₂, 2 NADH, 2 Acetyl-CoA

79
Q

how much carbons does Acetyl-CoA have?

A

2 carbons, the other carbon from pyruvate is in CO₂

80
Q

where does pyruvate oxidation occur?

A

mitochondrial matrix

81
Q

what happens to carbons in pyruvate in pyruvate oxidation?

A

oxidized into Acetyl-CoA and CO₂

82
Q

what is the net energy yield in pyruvate oxidation PER glucose molecule?

A

2 NADH molecules

83
Q

What occurs during the citric acid cycle?

A

glucose is completely oxidized into 6CO₂

chemical energy in bonds of Acetyl-CoA are transferred to ATP via substrate level phosphorylation and to NADH and FADH₂

84
Q

how is Acetyl-CoA completely oxidized in the citric acid cycle?

A

two carbons from Acetyl-CoA are added to oxaloacetate (4C), forming citrate (6C)

cycle continues, where citrate is converted back to oxaloacetate

85
Q

where does the citric acid cycle occur?

A

mitochondrial matrix

86
Q

what happened to carbons in acetyl-CoA in the citric acid cycle?

A

completely oxidized into CO₂

87
Q

what happened to the electrons of acetyl-CoA in the citric acid cycle?

A

transferred into 3 NADH and 1 FADH₂ molecules

88
Q

what is the NET energy yield from the citric acid cycle PER glucose molecule?

A

6 NADH, 2 FADH₂ and 2 ATP

89
Q

where is most of the energy from one glucose molecule stored from glycolysis up to the citric acid cycle?

A

in the electron carriers NADH and FADH₂

90
Q

what do the electron carriers do?

A

they donate electrons they carry to the electron transport chain (ETC), powering ATP synthesis via OXIDATIVE PHOSPHORYLATION

91
Q

what is the electron transport chain?

A

allows energy from electron carriers generated during glycolysis to the citric acid cycle to drive ATP synthesis in the inner mitochondrial membrane

  1. receives electrons from carriers
  2. transports electrons to electron acceptors
  3. generates proton gradient which drives ATP synthesis via oxidative phosphorylation
92
Q

what processes are involved in the electron transport chain?

A

chemiosmosis (diffusion dealing with ions) and oxidative phosphorylation

93
Q

what are mobile electron carriers? what is their purpose in the electron transport chain?

A

MECs are used to pass electrons between protein complexes called respiratory complexes in the ETC

94
Q

what respiratory complex does NADH enter?

A

Complex I

95
Q

what respiratory complexes does FADH₂ enter?

A

Complex II

96
Q

what is the final electron acceptor in the electron transport chain?

A

oxygen

97
Q

what happens to oxygen when it accepts electrons in the electron transport chain?

A

it is reduced into H₂O

98
Q

what happens if no oxygen is available to accept electron in the electron transport chain?

A

ETC fails to continue, ATP is not produced, resulting in cells dying due to lack of energy

99
Q

how does the electron transport chain create a proton gradient?

A

flow of electrons across ETC is coupled to pumping of H+ protons from mitochondrial matric across inner mitochondrial membrane into intermembrane space, creating conc. and electrical gradient

electrochemical gradient provides source of potential energy to synthesize ATP

100
Q

what does the presence of an electrochemical gradient do?

A

electrochemical gradient provides source of potential energy to synthesize ATP

101
Q

how do H+ in inner membrane space diffuse down their conc. gradient to mitochondrial matrix?

A

through protein channel called ATP synthase (complex 5)

102
Q

how is the potential energy of the H+ gradient released?

A

H+ crosses the inner mitochondrial membrane from intermembrane space to the mitochondrial matrix through ATP synthase

103
Q

Each pair of electrons released by NADH provides energy to produce how much ATP?

A

~ 2.5 ATP

104
Q

Each pair of electrons released by FADH₂ provides energy to produce how much ATP?

A

~ 1.5 ATP

105
Q

what is the max. # of ATP produced from one glucose molecule?

A

30-32

106
Q

where is the electron transport chain located?

A

inner mitochondrial membrane

107
Q

what is the net energy yield from oxidative phosphorylation?

A

about 26-28 ATP

108
Q

what happened in the electron transport chain in terms of redox reactions?

A

electron donors (reducing agents) transfer electrons to electron acceptors (oxidizing agents)

NADH and FADH₂ are oxidized, while oxygen is reduced

109
Q

how are cellular respiration reactions regulated?

A

level of energy/ATP in cell as well las level of NAD+/ NADH indicates how much energy a cell has available

110
Q

what happens when ATP levels are low?

A

when ATP levels low / ADP levels high, cell activates or upregulates pathways leading to ATP synthesis

111
Q

what happens when ATP levels are high?

A

when ATP levels high / ADP levels low, cell slows down or downregulates pathways leading to ATP synthesis

112
Q

what happens if cell has high levels of NAD+?

A

cell activates or upregulates pathways leading to ATP synthesis to consume NAD+

113
Q

what happens if cell has high levels of NADH?

A

cell slows down or downregulates pathways leading to ATP synthesis to prevent waste of NADH

114
Q

How is step 3 of glycolysis important?

A

step 3 of glycolysis (converting fructose 6-phosphate to fructose 1,6-bisphosphate) is catalyzed by PFK-1

step 3 is considered a committed, important step and is under tight control

115
Q

what is the role of phosphofructokinase-1 (PFK-1) in glycolysis regulation?

A

PFK-1 is an allosteric enzyme with many activators and inhibitors

when levels of ADP/AMP high(ATP low), molecules binds to PFK-1 and activates enzyme to continue glycolysis

when ADP/AMP low (ATP levels high), ATP binds to enzyme and inhibits its activity

116
Q

what categories of cellular poisons obstruct oxidative phosphorylation?

A
  1. blocks ETC (cyanide, CO)
  2. blocks H+ flow through ATP synthase
  3. make membrane leaky to H+
117
Q

what is brown fat? how does it benefit organisms when it interrupts cellular respiration?

A

brown fat generates heat due to abundance of mitochondria

brown fat inner membrane has protein that allows H+ to flow back down electrochemical gradient without generating ATP whilst generating heat

useful for hibernation

118
Q

what is anaerobic respiration?

A

cellular respiration with a molecule other than O₂ as its last electron acceptor

119
Q

what is fermentation?

A

reactions that regenerates NAD+, absence of oxygen

120
Q

what is lactic acid fermentation?

A

pyruvate is broken down via fermentation in absence of oxygen

electrons from NADH are transferred to pyruvate to produce lactic acid and NAD+

occurs in animals and bacteria

121
Q

what is reaction formula for lactic acid fermentation?

A

Glucose + 2ADP + 1P = 2 lactic acid + 2ATP + 2H₂O

122
Q

what is alcohol fermentation?

A

pyruvate releases CO₂ to form acetaldehyde, electrons from NADH are transferred to acetaldehyde to form ethanol and NAD+

123
Q

what is function of coenzyme Q?

A

facilitate transport of electrons from complex I to III and complex II to III

124
Q

what is function of cytochrome C?

A

facilitate electron transport from complex III to IV

125
Q

why does NADH produce more ATP than FADH₂?

A

electrons from NADH are activating more proton pumps compared to electrons from FADH₂, which activate less proton pumps.

As electrons move through complex I in a series of redox reactions, energy is released, and the complex uses this energy to pump protons from the matrix into the intermembrane space

Complex II does not have the ability to pump protons against gradient

126
Q

how does NADH have higher potential energy?

A

activates complex I, III, and IV while FADH₂ only activates complex III and IV

127
Q

what is difference between substrate-level phosphorylation and oxidative phosphorylation?

A

BIOL1115 LECTURE (11 decks)

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