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01 Bioenergetics Flashcards

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1
Q

Describe what is meant by the term glycolysis and what it is the initial component of?

A

“lysis” = breaking, of glucose.
Aerobic metabolism

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2
Q

Describe the process and products of aerobic and anaerobic metabolism

A

Aerobic - pyruvate
Anaerobic - “fermentation” and produces lactate or ethanol

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3
Q

What is the end product of glycolysis? (energy and molecule)

A

2 net ATP and pyruvate

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4
Q

State what products are formed at each of the 10 steps in glycolysis

A
  1. Glucose
  2. Glucose-6-phosphate
  3. Fructose-6-phosphate
  4. Fructose-1,6-bisphosphate
  5. GAP (glyceraldehyde-3-phosphate) / DAP (dihydroxyacetone phospahte)
  6. 1,3-bisphosphoglycerate
  7. 3-phosphoglycerate
  8. 2-phosphoglycerate
  9. phosphoenolpyruvate
  10. Pyruvate
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5
Q

What steps is ATP invested and produced in glycolysis?

A

ATP invested in 1-2 (glucose to glucose-6-phosphate) and in 3-4 (fructose-6-phosphate to fructose-1,6-bisphosphate)

ATP produced in 6-7 (1,3-bisphosphoglycerate to 3-phosphoglycerate) and 9-10 (phosphoenolpyruvate to pyruvate)

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6
Q

Name the 5 properties of water

A
  • powerful solvent
  • polarity attracts positive and negative charges
  • forms barriers with hydrophobic molecules (lipids —> membranes)
  • allows/drives structure and shape of molecules, base pairing of DNA
  • transports substrates
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7
Q

How did life’s chemistry most likely begin?

A
  • interactions on the surface of rocks and clays
  • high temperatures driving reactions
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8
Q

Explain the relevance of Miller and Urey’s findings

A
  • recreating the environment in which earth was created
  • amino acids and metabolites could from
  • life likely started from an abundance of organic molecules and elements
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9
Q

How are polymers formed?

A

dehydration

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10
Q

What are the basic subunits of polymers called?

A

monomers

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11
Q

Name the 4 types of polymers

A

lipids, polysaccharides, proteins and nucleic acids

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12
Q

How does the presence of polymers tell us where life started?

A

polymers are the basic structural units of macromolecules, and life requires macromolecules

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13
Q

What is the initial building block of a lipid called?

A

acetate

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14
Q

What makes fatty acids amphipathic?

A

addition of phosphate

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15
Q

Name the three functions of lipids

A
  • energy storage
  • structural molecules (membranes)
  • steroid hormones
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16
Q

Name the subunits of a fat/ triglyceride molecule and state the bond between them

A
  • glycerol, 3 fatty acid chains
  • ester linkage
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17
Q

What is the difference between saturated and unsaturated fatty acids?

A
  • saturated - all carbons are bonded to hydrogen in the FA chain, no kinks, pack closely together
  • unsaturated - kinks, hard to rotate, cant pack close together
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18
Q

What is the structure of a phospholipid and what makes this special in terms of beginning of life?

A

2 fatty acid chains, glycerol and a phosphate linked group - hydrophilic and hydrophobic regions - make micelle - first from of replication

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19
Q

What is a different name for disaccharide?

A

oligosaccharide

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20
Q

What is the name of the bond in polysaccharides?

A

glycosidic linkages

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21
Q

What is the function of polysaccharides?

A

energy storage and structure

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22
Q

Name the two main polysaccharides for energy storage

A

glycogen and starch

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23
Q

Name the two main polysaccharides for structure

A

Chitin and cellulose

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24
Q

State a structural difference between glycogen and starch and why this is of significance

A
  • starch has fewer branches, glycogen has extensive branching.
  • the branching in glycogen is due to the fact that humans move a lot more and need to pack in more glycogen for energy storage and fuel
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25
Q

Where is glycogen stored?

A

liver and muscle

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26
Q

State the bonding type in glycogen and starch and its significance

A

alpha 1-4 bond, flexible and can move

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27
Q

State the bonding in cellulose and chitin and its significance

A

beta 1-4 - cannot rotate

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28
Q

What are nucleic acids?

A

they form DNA and RNA

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29
Q

What is the structure of a polynucleotide?

A

phosphate group, pentose sugar and a nitrogenous base

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30
Q

What bond is in polynucleotides?

A

phosphodiester bond

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31
Q

What do nucleic acids and proteins have in common structurally

A

they are composed of variating monomers

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32
Q

What 2 structural units in nucleic acids can differ, explain the difference

A
  • nitrogenous bases: can be purines or pyrimidines (Purines - larger AG and Pyrimidines - smaller CTU)
  • phosphate sugar: deoxyribose or ribose sugar
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33
Q

Breakdown is a _______ process

A

catabolic

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34
Q

Build up is an _______ process

A

anabolic

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35
Q

Describe the breakdown of ATP and how it provides energy

A

ATP breaks down into ADP and Phosphate. This releases energy and can fuel other reactions

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36
Q

How does ADP turn into ATP?

A

through digestion and the breakdown of molecules, providing energy to turn ADP back to ATP. this is exergonic

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37
Q

What is the difference between and endergonic and exergonic reaction?

A

exergonic reactions release energy whilst endergonic reactions require energy input

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38
Q

State the 4 exit pathways of heat during food consumption

A
  • digestion and absorption
  • cellular respiration
  • biosynthesis
  • cellular work
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39
Q

State two ways in which energy is lost during food consumption

A

through feaces (undigested material such as cellulose) and through nitrogenous waste in urine

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40
Q

What macromolecule releases the most energy and which one the least ?

A

fats release the most, carbohydrates release the least

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41
Q

Which molecule is key to the synthesis of ATP and describe pathway?

A
  • acetyl coa
  • macromolecules broken down to micro nutrients, these make acetyl coa, acetyl coa feeds into citric acid cycle, the electron transport chain which generates ATP
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42
Q

Why is fat the most efficient molecule to release energy?

A

easier for enzymes to get to the C-H and C-OH bonds instead of C-C bonds.

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43
Q

Why is ATP the source of energy? (selected for)

A

most stable in water and water is essential to life

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44
Q

Why is ATP the source of energy? (selected for)

A

most stable in water and water is essential to life

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45
Q

What part of ATP carries the energy and explain how?

A
  • phosphate
  • phosphates joined together repel each other making the charges move to different sides (push away) - energy in the molecule, wants to break off
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46
Q

What makes ATP more powerful?

A

when the phosphates attract calcium or magnesium. it changes how the charges interact and gives the terminal phosphate more charge

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46
Q

Define Gibbs free energy

A

amount of energy that can be liberated from things - how much work we can do

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47
Q

What is the formula for Gibbs free energy?

A

Gibbs free energy = Δenthalpy - (temperature x Δentropy)

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48
Q

Why does a reaction with -ve gibbs free energy happen more spontaneously?

A

reaction is releasing energy, it is exergonic compared to a +ve gibbs value where energy must be supplied for the reaction to occur

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49
Q

How do ATP and gibbs free energy relate and give an example?

A
  • ATP can drive unfavourable reactions
  • glutamic acid + ammonia to form glutamine is an endergonic reaction.
  • ATP phosphorylates glutamic acid making the aa less stable
  • ammonia displaces the phosphate group forming glutamine
  • this reaction is now exergonic
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50
Q

Describe the general energy flow through life

A
  • photosynthesis
  • organic molecules + oxygen feeds into mitochondria
  • mitochondria generates ATP which powers cellular work
  • carbon dioxide and water released - feeds back into photosynthesis.
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51
Q

How does digestion supply regeneration of ATP

A

it provides macronutrient fuel sources that supply substrates to regenerate ATP (eg. Deaminated amino acids, glucose and free fatty acids)

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52
Q

What are the three stages of catabolism that are used to generate ATP?

A
  1. hydrolysis of complex molecules to their building blocks
  2. conversion of building blocks to Acetyl CoA
  3. Oxidation of acetyl CoA occurs by oxidative phosphorylation
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53
Q

What are the two laws of thermodynamics?

A
  1. energy cannot be created or destroyed, only converted
  2. The universe is becoming increasingly disordered
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54
Q

What is the formula for the first law of thermodynamics?

A

ΔH= q+ w (change in enthalpy is heat + work)

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55
Q

What is the significance of a -ΔG

A

the more negative, the more work that can be done. BUT it does not predict the rate at which reaction will occur!!

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56
Q

Why is oxidation important in metabolic pathways?

A

Oxidation reactions extract energy from bonds because leaving hydrogens take electrons (used in metabolic pathways)

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57
Q

What enzymes do redox reactions use?

A

de-hydrogen-ases

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58
Q

How many net ATP does glycolysis produce

A

two

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59
Q

What are the three stages of cellular respiration?

A

glycolysis, citric acid cycle, oxidative phosphorylation

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60
Q

what is KM?

A

Km value is equal to the substrate concentration at which half of the enzyme active sites are saturated with the substrate.

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61
Q

What is the relationship between KM and affinity?

A

A high KM = low affinity (it takes more substrate to get to Vmax)

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62
Q

At what stage is glucose trapped in the cell?

A

When glucose is converted to glucose6-phosphate. The addition of the phosphate makes glucose highly polar and polar molecules cannot cross the cell membrane, it is also no longer recognised by the GLUT transporters.

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63
Q

What is the commitment step in glycolysis?

A
  • When fructose-6-phosphate is converted to fructose-1-6-bisphosphate. Fructose-1,6-bisphosphate can only undergo the reaction of glycolysis. (i.e. ready for catabolism)
  • PFK enzyme

(The components of the pathway up to this point can have other metabolic directions.)

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64
Q

In what stages of glycolysis is ATP invested?

A
  1. Glucose - glucose.6-phosphate
  2. Glucose-6-phosphate Fructose-1,6-bisphosphate
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65
Q

At what step does a redox reaction occur is glycolysis?

A

Glyceraldehyde-3-phosphate to 1,3-bisphosphiglycerate.
The cofactor NADH is used and a P is added

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66
Q

What enzyme produces NADH + H+ in glycolysis?

A

GAPDH - Glyceraldehyde-3-phosphoate dehydrogenase

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67
Q

In whats steps in glycolysis is ATP generated?

A
  1. 1,3-bisphosphoglycerate to 3-phosphoglycerate
  2. Phosphoenolpyruvate to pyruvate
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68
Q

What are the products of glycolysis ?

A

2 ATP net and 2 NADH

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69
Q

What 3 enzymes are highly regulated in glycolysis?

A

Hexokinase/glucokinase
Phosphofructokinase
Pyruvate Kinase

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70
Q

How is PFK regulated?

A
  • high ATP (why make more and waste glucose)
  • AMP activates PFK (low ATP - make more)
  • Citrate inhibits PFK
  • Acidification inhibits PFK
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71
Q

What molecule is used in anaerobic glycolysis ? What are the drawbacks and benefits of anaerobic metabolism?

A

NAD - produces lactate
enzyme - lactate dehydrogenase (LDH)
15x less ATP, but 100x faster

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72
Q

What is the cori cycle?

A

the metabolic pathway in which lactate produced by anaerobic glycolysis in the muscles moves to the liver and is converted to glucose, which then returns to the muscles and is metabolized back to lactate.

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73
Q

What is the main function of the CAC?

A

oxidise acetyl-CoA

74
Q

What is the fate of pyruvate in the CAC?

A

Pyruvate is converted to Acetyl-CoA which is then further oxidised to CO2

75
Q

What are the four oxidation or dehydrogenation reaction which transfer electrons to the electron accepting coenzymes NAD+ and FAD?

A
  1. Isocitrate to alpha-ketoglutarate (NADH is formed)
  2. alpha-ketoglutarate to succinyl co-A (NADH is formed)
  3. Succinate to Fumarate (FADH2 is formed)
  4. Malate to oxaloacetate (NADH is formed)
76
Q

What are the steps of converting pyruvate to Acetyl CoA

A
  1. a carboxyl group is removed from the pyruvate by pyruvate dehydrogenase, releasing carbon dioxide
  2. NAD + is reduced to NADH
  3. an acetyl group is transferred to Coenzyme A resulting in Acetyl CoA
77
Q

Is the conversion of pyruvate to Acetyl CoA reversible? Explain.

A

No. very large –ΔG, and regulated

78
Q

What are the three coenzymes of the CAC cycle?

A

Coenzyme A, NAD+ and FAD

79
Q

What are the steps of the CAC and what are the enzymes involved?

A
  1. acetyl CoAjoins with oxaloacetate through the enzyme citrate synthase, releasing theCoA and forming citrate.
  2. Citrate is converted to isocitrate by 1. the removal of water and 2. the additon of water (rearrangement enables OH oxidation) by the enzyme aconitase
  3. Isocitrate is oxidised, released one CO2, forming α-ketoglutarate. NAD is reduced to NADH by the enzyme isocitrate dehydrogenase
  4. α-ketoglutarate is oxidised, reducingNAD toNADHand releasing a molecule of carbon dioxide in the process. The remaining four-carbon molecule picks up Coenzyme A, forming the unstable compound succinylCoA. The enzyme catalysing this step,α-ketoglutarate dehydrogenase.
  5. CoA is replaced by a phosphate group (in succinyl CoA), and substrate level phosphorylation occurs either GTP or ATP is made. enzyme is succinyl CoA synthase
  6. Succinate is oxidised by succinate dehydrogenase, forming fumarate. two hydrogen atoms—with their electrons—are transferred to FAD, producing FADH2. The enzyme that carries out this step is embedded in the inner membrane of the mitochondrion (complex II), so FADH2 can transfer its electrons directly into the electron transport chain.
  7. enzyme fumerase adds water to fumarate, converting it into malate.
  8. malate is oxidised by malate dehydrogenase forming oxaloacetate Another molecule ofNAD is reduced toNADHin the process.
80
Q

In the CAC during substrate level phosphorylation, where is GTP and ATP made?

A

GTP - liver
ATP - muscles

81
Q

For two pyruvate molecules, what are the products of the CAC?

A

6CO2
8NADH
2FADH2
2GTP or ATP

82
Q

What are the CAC intermediates used for? Give a few examples.

A

Biosynthesis of important molecules
Ex. Oxaloacetate - aa synthesis
Malate - glucose (glucogenesis)
Citrate - Fatty acids

83
Q

What would happen if arsenic was added to the CAC?

A

α-ketoglutarate dehydrogenase and pyruvate dehydrogenase are both poisoned/inhibited = reduced conversion of pyruvate to acetyl coenzyme A (CoA), so that both the citric acid cycle activity and production of cellular ATP are decreased

84
Q

How is the citric acid cycle regulated?

A

The citric acid cycle is controlled through the enzymes that break down the reactions that make the first two molecules of NADH.

depends on levels of ATP and NADH

85
Q

What are the three regulatory enzymes of the CAC and how are they regulated?

A
  1. citrate synthase - inhibited by high concentrations of ATP, acetyl-CoA, and NADH
  2. isocitrate dehydrogenase - ATP and NADH inhibit, ADP activates
  3. α-ketoglutarate dehydrogenase - ATP , NADH and succinyl CoA inhibit
86
Q

How is pyruvate dehydrogenase regulated?

A

ATP, Acetyl CoA and NADH inhibit
Pyruvate and ADP activate

87
Q

Phospholipids are composed of?

A

a phosphate group, a glycerol and fatty acids

88
Q

What oils are rich in unsaturated fats?

A

plant oils

89
Q

A function of cholesterol that does not harm health is its role _____.

A

as a component of animal cell membranes

90
Q

What is the general formula for carbohydrates?

A

Cn(H2O)n

91
Q

A carbohydrate that yields many monosaccharides when hydrolyzed is a ____?

A

polysaccharide

92
Q

A simple sugar is composed of equal parts carbon and water, which gave rise to the general name of any sugar as a ___?

A

carbohydrate

93
Q

Lactose, the sugar in milk, is a ___
, because it can be split into two monosaccharides.

A

disaccharide

94
Q

A ____ cannot be hydrolyzed any further. (carb)

A

monosaccharide

95
Q

Glycogen is _____.

A

a polysaccharide found in animals

96
Q

glucose + glucose —> _____ by _____.

A

maltose + water … dehydration synthesis

97
Q

_____ is the most abundant organic compound on Earth.

A

cellulose

98
Q

What is another name for a condensation reaction?

A

dehydration

99
Q

What is the name of the process during which a bond between two monomers is broken?

A

hydrolysis

100
Q

hydrolysis is the opposite to?

A

condensation

101
Q

Nucleic acid polymers are made up of ___ monomers.

A

nucleotide

102
Q

Carbohydrate polymers are made up of ___ monomers.

A

simple sugar

103
Q

Protein polymers are made up of
___ monomers.

A

amino acid

104
Q

Energy is captured and stored in ____ bonds and is transferred to ____ following their ____

A

reduced (C=O, C-C, C-H)
ATP
oxidation

105
Q

Explain how energy is harnessed from ATP

A

ATP is ionised in the cell and negative charges are crowded on the terminal phosphate, breaking bond releases energy

106
Q

What is the free energy released on ATP hydrolysis used for

A

biological work

107
Q

What releases the most energy in terms of phosphate removal from ATP

A

first phosphate i.e. ATP to ADP

108
Q

What role does food play in the production of ATP?

A

ADP must be converted back to ATP, thus food is used as fuel to produce energy that is needed to convert ADP back to ATP.

109
Q

Describe the general flow of energy through an organism

A

organic molecules in food - digestion and absorption - nutrient molecules in body cells - cellular respiration or carbon skeletons used for biosynthesis

110
Q

What are the two major energy stores of the body

A

glycogen and fat

111
Q

Explain how energy stores are metabolised to provide energy

A

proteins, triglycerides and gylcogen –> amino acids, glucose (gluconeogenesis) and fatty acids - blood stream - converted to acetyl coa - mitochondria to make ATP

112
Q

List the three stages of catabolism

A
  1. hydrolyse macromolecules
  2. production of acetyl coa from building blocks
  3. oxidation of acetyl coa to produce ATP
113
Q

Describe the ATP ADP cycle

A

ATP to ADP requires input of H2O (hyrolysis) - exergonic
ADP to ATP releases H2O as byproduct (condensation reaction), endergonic (requires input of energy)

114
Q

Which part of the adenosine triphosphate molecule is released when it is hydrolyzed to provide energy for biological reactions?

A

γ -phosphate (the terminal phosphate)

(The γ -phosphate is the primary phosphate group on the ATP molecule that is hydrolyzed when energy is needed to drive anabolic reactions. Located the farthest from the ribose sugar, it has a higher energy than either the α - or β -phosphate.)

115
Q

What type of reaction breaks the bonds that join the phosphate groups in an ATP molecule?

A

hydrolysis

116
Q

Chemical energy is a form of _____ energy.

A

potential

117
Q

In your body, what process converts the chemical energy found in glucose into the chemical energy found in ATP?

A

cellular respiration

118
Q

What are the by-products of cellular respiration?

A

heat, carbon dioxide, and water

119
Q

If products have less potential energy, what type of reaction is this, what does it give off?

A

energy released to the surroundings - exergonic - releases heat. Occurs spontaneously - downhill

120
Q

If products have more potential energy, what type of reaction is this?

A

reactants absorb energy from the surroundings, endergonic. - does not occur spontaneously - upward hill

121
Q

The following reaction
A –> B + C + heat
is a(n) _____ reaction.

A

exergonic

122
Q

A(n) _____ reaction occurs spontaneously.

A

exergonic

123
Q

In cells, what is usually the immediate source of energy for an endergonic reaction?

A

ATP

124
Q

The reaction ADP + P –> ATP is a(n) _____ reaction.

A

endergonic

125
Q

The energy for an endergonic reaction comes from a(n) _____ reaction.

A

exergonic

126
Q

What is the fate of the phosphate group that is removed when ATP is converted to ADP?

A

It is acquired by a reactant in an endergonic reaction. By acquiring the phosphate group the reactant acquires energy.

127
Q

What is energy coupling?

A

the use of energy released from an exergonic reaction to drive an endergonic reaction

128
Q

Where does glycolysis occur in the cell

A

the cytosol

129
Q

Where are electrons transferred in the citric acid cycle?

A

The citric acid cycle transfers electrons to NADH and FADH2.

130
Q

What is the final electron acceptor of cellular respiration

A

oxygen

131
Q

The name given to the reaction of transfer of electrons in cellular respiration is given a special name. what is this name?

A

Redox reactions

132
Q

In glycolysis, the carbon-containing compound that functions as the electron donor is?

A

Glucose

133
Q

Once the electron donor in glycolysis gives up its electrons, it is oxidized to a compound called?

A

pyruvate

134
Q

What compound functions as the electron acceptor in glycolysis.

A

NAD+

135
Q

The reduced form of the electron acceptor in glycolysis is?

A

NADH

136
Q

Among the products of glycolysis, which compounds contain energy that can be used by other biological reactions?

A

pyruvate, ATP and NADH

137
Q

In glycolysis, ATP molecules are produced by _____.

A

substrate level phosphorylation - A phosphate group is transferred from glyceraldehyde phosphate to ADP.

138
Q

Define substrate level phosphorylation

A

involves the addition of a phosphate group to another molecule. occurs in the cytoplasm in glycolysis and in the mitochondrial matrix in the CAC.

139
Q

How many NADH are produced by glycolysis?

A

2

140
Q

FADH2 is a product of?

A

the citric acid cycle

141
Q

In glycolysis, what starts the process of glucose oxidation?

A

ATP

142
Q

In glycolysis there is a net gain of _____ ATP.

A

2

143
Q

In muscle cells, fermentation produces _____.

A

lactate and NAD+

144
Q

In fermentation _____ is reduced and _____ is oxidized.

A

pyruvate … NADH

(The pyruvate from glycolysis is reduced to either lactate or ethanol, and NADH is oxidized to NAD+.)

145
Q

List the three types of pyruvate metabolism

A

lactate - fermentation in human muscle

ethanol - fermentation in yeast and bacteria

acetyl CoA - aerobic oxidation

146
Q

In the presence of ___, human cells carry out ___ respiration, which yields ___. In the absence of oxygen, human cells can carry out ___, which yields ___. ___ and many ___ carry out ___, which takes place under ___ conditions, and produces ___.

A

oxygen, aerobic, acetyl CoA, lactic acid fermentation, lactate, yeasts, bacteria, alcohol fermentation, anaerobic, ethanol

147
Q

What are the reactants of anaerobic lactic acid fermentation

A

NADH and pyruvate

148
Q

What are the products of anaerobic lactic acid fermentation

A

NAD+ and lactate

149
Q

Which term describes the degree to which an element attracts electrons?

A

electronegativity

150
Q

Which terms describe two atoms when they form a bond in which electrons are completely transferred from one atom to the other?

A

anion and cation

151
Q

What molecule enters the citric acid cycle?

A

acetyl coa

152
Q

In the citric acid cycle, ATP molecules are produced by _____.

A

Substrate-level phosphorylation

  • A phosphate group is transferred from GTP to ADP.
153
Q

Name the products of the citric acid cycle

A

FADH2, NADH + H+, CO2, ATP

154
Q

Draw out the citric acid cycle and show the carbon skeletons of each intermediate

A

//

155
Q

in the cac pyruvate is oxidised to ?

A

CO2

156
Q

In the cac NAD+ is reduced to?

A

NADH

157
Q

in the cac FAD is reduced to ?

A

FADH2

158
Q

Why is the citric acid cycle a cyclic pathway rather than a linear pathway?

A

It is easier to remove electrons and produce CO2 from compounds with three or more carbon atoms than from a two-carbon compound such as acetyl CoA.

159
Q

For each glucose that enters glycolysis, _____ acetyl CoA enter the citric acid cycle.

A

2 - Each glucose produces two pyruvates, each of which is converted into acetyl CoA

160
Q

For each glucose that enters glycolysis, _____ NADH + H+ are produced by the citric acid cycle.

A

6 - 3 NADH + H+ are produced per each acetyl CoA that enters the citric acid cycle.

161
Q

In cellular respiration, most ATP molecules are produced by _____.

A

oxidative phosphorylation

162
Q

The final electron acceptor of cellular respiration is _____.

A

oxygen

163
Q

During electron transport, energy from _____ is used to pump hydrogen ions into the _____.

A

NADH and FADH2 … intermembrane space

164
Q

What is the function of ATP synthase

A

phosphorylates ADP

165
Q

The proximate (immediate) source of energy for oxidative phosphorylation is _____.

A

kinetic energy that is released as hydrogen ions diffuse down their concentration gradient

166
Q

In mitochondrial electron transport, what is the direct role of O2 ?

A

to function as the final electron acceptor in the electron transport chain

167
Q

How would anaerobic conditions (when no O2 is present) affect the rate of electron transport and ATP production during oxidative phosphorylation? (Note that you should not consider the effect on ATP synthesis in glycolysis or the citric acid cycle.)

A

Both electron transport and ATP synthesis would stop.

Without O2 , mitochondria are unable to oxidize the NADH and FADH2 produced in the first three steps of cellular respiration, and thus cannot make any ATP via oxidative phosphorylation. In addition, without O2 the mitochondria cannot oxidize the NADH and FADH2 back to NAD+ and FAD , which are needed as inputs to the first three stages of cellular respiration.

168
Q

why is more ATP made per molecule of NADH than per molecule of FADH2 ?

A

Fewer protons are pumped across the inner mitochondrial membrane when FADH2 is the electron donor than when NADH is the electron donor.

169
Q

What is the effect of gramicidin on oxidative phosphorylation?

A

When the protein gramicidin is integrated into a membrane, an H+ channel forms and the membrane becomes very permeable to protons ( H+ ions).

170
Q

If gramicidin is added to an actively respiring muscle cell, how would it affect the rates of electron transport, proton pumping, and ATP synthesis in oxidative phosphorylation?

A
  • rate of ATP synthesis and size of proton gradient decreases
  • electron transport rate, proton pumping rate and rate of oxygen uptake remains the same
171
Q

___is a multi-protein complex within the electron transport chain.

A

Complex III

172
Q

___donates electrons to the electron transport chain.

A

NADH

173
Q

____ is a nonprotein organic electron carrier within the electron transport chain.

A

Q (ubiquinone)

174
Q

___is a prosthetic group present in several components of the electron transport chain.

A

Fe-S

175
Q

Of the electron transport compounds, list them in order from the one containing electrons with the highest free energy to the one containing electrons with the lowest free energy.

A

FADH2 – FMN of Complex I – Fe-S of Complex II – Q – Fe-S of Complex III – Cyt c – Cyt a of Complex IV – O2

(not all listed here)

176
Q

Approximately how much more free energy is supplied to the electron transport chain by NADH than by FADH2?

A

8 kcal/mol

177
Q

What is the correct order of electron transport compounds from least electronegative to most electronegative?

A

NADH – Fe-S of Complex I – Q – Fe-S of Complex III – Cyt c– Cyt a of Complex IV – O2

178
Q

Under anaerobic conditions (a lack of oxygen), the conversion of pyruvate to acetyl CoA stops. Why?

A

In the absence of oxygen, electron transport stops. NADH is no longer converted to NAD+, which is needed for the first three stages of cellular respiration.

179
Q

Suppose that a cell’s demand for ATP suddenly exceeds its supply of ATP from cellular respiration. Explain what would happen how how ATP production is increased

A

ATP levels would fall at first, decreasing the inhibition of PFK and increasing the rate of ATP production.

180
Q

How is glucose taken up into the cell?

A

facilitated transport with Na+

181
Q

High Km is ___ affinity

A

low

182
Q

What is the role of NAD+/NADH in cellular respiration?

A

The molecule acts as a shuttle for electrons during cellular respiration. At various chemical reactions, the NAD+ picks up an electron from glucose, at which point it becomes NADH. Then NADH, along with FADH2 will ultimately transport the electrons to the mitochondria, where the cell can harvest energy stored in the electrons.

Biosci 101 (3 decks)

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