Chapter 6 - Energy Transfer in the Body Flashcards
1
Q
What is the Energy Currency of the Body?
A
- ATP
2
Q
What provides major sources of potential energy?
A
- Macronutrients
3
Q
How does ADP form?
A
- When ATP joins with water
4
Q
What enzyme catalyzes the reaction of ATP and Water to form ADP?
A
- Adenosine Triphosphatase (ATPase)
5
Q
What are the Cells’ two major energy-transforming activities?
A
- Extract potential energy from food/conserve it within ATP bonds
- Extract/transfer chemical energy in ATP to power biological work
6
Q
How much ATP does the body store at resting condition?
A
- 80-100g ATP
7
Q
How long can resting stores of ATP in the body provide energy?
A
2-3 seconds of Maximal Exercise
8
Q
Which ways can the mitochondria produce ATP?
A
Methods
- Citric Acid Cycle
- Respiratory Chain (Aerobic)
Fuel sources
- fatty acids
- Pyruvate from glucose
- Some deaminated amino acids
9
Q
Which ways for ATP production occur in the Cytosol?
A
- anaerobic glycolysis
-using glucose and glycogen - adenylate kinase
- Glycerol
- Some Deamniated Amino Acids
- Phosphocreatine shuttle
10
Q
Where does Aerobic ATP production occur?
A
- Mitochondria
11
Q
Where does Anaerobic ATP production occur?
A
- Cytosol
12
Q
Where does ATP production from phosphocreatine occur?
A
- Cytosol
13
Q
What happens with the anaerobic splitting of a phosphate from Phosphocreatine?
A
- ATP resynthesis
14
Q
How much Phosphocreatine do cells store compared to ATP?
A
- 4-6 times
15
Q
How long can Phosphocreatine provide energy for?
A
- around 10s
16
Q
What does Adenylate Kinase Reaction represent?
A
- single-enzyme mediated reaction for ATP
- 2 adp -> atp + amp
17
Q
cellular oxidation: Where does most energy for phosphorylation derive from?
A
oxidation of:
- Carbohydrates
- Lipids
- Protein
18
Q
cellular respiration: What do oxidation reactions do?
A
- Donate electrons
19
Q
cellular respiration: What do Reduction reactions do?
A
- Accept Electrons
20
Q
cellular respiration: What constitutes the biochemical mechanism that underlies energy metabolism?
A
- RedOx Reactions (oxidation - reduction)
21
Q
cellular respiration: What do redox reactions provide from catabolism of stored macronutrients?
A
- Hydrogen Atoms
22
Q
cellular respiration: what do the carrier molecules in mitochondria do?
A
- Remove electrons from hydrogen (oxidation)
- Pass them to oxygen (reduction)
- Synthesize ATP through redox
23
Q
cellular oxidation: What catalyze’s hydrogen’s release from the nutrient substrate?
A
- substrate-specific dehydrogenase enzymes
24
Q
cellular oxidation: What accepts pairs of electrons from hydrogen?
A
- coenzyme component of the dehydrogenase
25
cellular respiration: What happens when Nicotinamide Adenine Dinucleotide (NAD+) gains hydrogen and two electrons?
-Reduces to NADH
26
cellular respiration: What happens to the other Hydrogen when one pairs with NAD+?
- Appears in the cell fluid as H+
27
cellular respiration: How many electrons does Flavin Adenine Dinucleotide accept?
- Two
28
cellular oxidation: What are NAD+ and FAD?
- Electron Acceptors
29
electron transport: What are Cytochromes?
- A series of Iron-protein electron carriers dispersed on the inner membranes of the mitochondrion
30
electron transport: What do cytochromes do
pass pairs of electrons carried by NADH and FADH2 down the chain
31
electron transport: what is electron transport
final common pathway where electrons extracted from hydrogen pass to oxygen
32
electron transport: What drives the respiratory chain? How?
Oxygen
- serving as final electron acceptor to combine with hydrogen to form water
33
electron transport: What happens for each pair of hydrogen atoms that reach the cytochrome?
- Two Electrons flow down the chain and reduce to one atom of oxygen
34
electron transport: What is released during the passage of electrons down the chain?
- Enough energy to re-phosphorylate ADP to ATP`
35
oxidative phosphorylation: How does oxidative phosphorylation synthesize ATP?
- Transfer of electrons from NADH and FADH2 to oxygen
36
oxidative phosphorylation: How much ATP synthesis occurs in the respiratory chain by oxidative reactions coupled with phosphorylation?
> 90%
37
oxidative phosphorylation: How many coupling sites during the electron transport does energy transfer from NADH to ADP to reform ATP?
- three distinct places
38
oxidative phosphorylation: Why do only 2 ATP molecules form for each hydrogen pair oxidized from FADH2?
- FADH2 enters respiratory chain at lower energy level, beyond point of first ATP synthesis
39
oxidative phosphorylation: how much energy is generated since the shuttling of hydrogen in the electron transport chain requires energy?
On Average
- NADH produces 2.5 ATP
- FADH2 produces 1.5 ATP
40
How much energy does 1 mole of ATP formed from ADP + P conserve?
- 7kcal energy
41
What is the relative efficiency level for harnessing chemical energy via the electron transport oxidative phosphorylation?
- 34%
42
Coupling electron transport-oxidative phosphorylation: What is created by electron transport energy-releasing reactions in the mitochondria?
- Proton (H+) gradient across the inner mitochondrial membrane
43
What provides the electrochemical basis for coupling electron transport to oxidative phosphorylation to form ATP?
* energy from NADH and FAD2H are used to pump H+ into intermembrane space
* flow of H+ into mitochondria matrix down gradient generates energy to rephosphorylate ADP
44
Which three prerequisites exist for continual re-synthesis of ATP during coupled oxidative phosphorylation?
- Tissue availability of NADH and FADH2
- Presence of oxygen in tissue (oxidizing agent)
- Sufficient concentration of enzyme and mitochondria to ensure energy transfer reactions proceed at appropriate rate
45
What are the 6 fuel sources?
- Phosphocreatine
- Anaerobic Glycolysis
- Blood Glucose (derived from liver glycogen)
- Triacylglycerol and Glycogen Molecules within muscles
- Free Fatty Acids (from liver triacylglycerols and adipocytes)
- Carbon Skeleton of Amino Acids
46
What controls the phosphorylation of ADP from PCr?
Enzyme Control
- Creatine Kinase
- Adenylate Kinase
47
Where are triacylglycerol's stored?
- Within Muscle Cells
48
Where are the carbon skeletons of amino acids located?
- Intramuscular
- Liver-derived
49
What is the only macronutrient substrate whose stored energy generates ATP without oxygen?
- Carbohydrates
50
What is required for processing a large quantity of fat for energy?
- minimal carbohydrate breakdown
51
What aerobic breakdown occurs faster, Carbs or Fats?
- Carbs
52
What requires an uninterrupted supply of carbs to function properly?
- The central nervous system
53
If we received 100% of energy from 1 full glucose, how much energy would we get?
- 686 kcal
54
How do we determine the yield of ATP from the breakdown of 1 Glucose?
1 Full Glucose 100% - 686kcal
34% Efficiency - 686x0.34 = 233kcal
7.3kcal/mol
233kcal/7.3kcal/mol = 32mol
55
What happens to the rest of the potential energy after the breakdown of glucose?
- Dissipated as heat
56
What are the two forms of carbohydrate breakdown?
- Anaerobic Glycolysis
- Aerobic Glycolysis
57
How much energy is released from Anaerobic Glycolysis of Glucose?
- 5%
58
What results from the Anaerobic Glycolysis of Glucose?
## Footnote
by-product and energy release yield
- pyruvate-to-lactate formation
- Release of 5% energy
59
What is the result of Aerobic Glycolysis of Glucose?
- Pyruvate-to-Acetyl Coenzyme A- to Citric Acid Cycle and Electron transport chain
- Release of all available energy from glucose
60
What is the First Step of Anaerobic Glycolysis?
- Glucose to Glucose 6-phosphate
61
What does the conversion of Glucose to Glucose-6-phosphate require?
- 1 ATP
- Hexokinase Enzyme
62
What does the Enzyme Hexokinase catalyze?
- Glucose to Glucose-6-phosphate
63
What is not required to convert Glycogen to Glucose-6-phosphate?
- ATP
- Hexokinase Enzyme
64
Where does Glycolysis take place?
- Cytosol
65
What does Glucose break down into following Glycolysis? What does it net?
- 2 Pyruvates
- Gains 2 ATP
66
What does Glycogen break down into following glycolysis? what does it net?
- 2 Pyruvates
- Gain 3 ATP
67
What is Glycogenesis?
- Glycogen Synthesis
68
Explain Glycogenesis
Glycogen Synthesis
- Surplus Glucose forms Glycogen
- Occurs in low cellular activity
- Facilitate by Glycogen Synthase
- Glucose links to large Glycogen molecules
69
What is Glycogenolysis?
- Glycogen Breakdown
70
Explain Glycogenolysis.
Glycogen Breakdown
- Glycogen breakdown to glucose
- occurs in high cellular activity with glucose depletion
71
What regulates Glycolysis?
- Levels of substrate fructose 1,6-diphosphate
- high oxygen inhibits
- Concentration of 4 enzymes
72
What 4 enzymes regulate Glycolysis?
- Hexokinase
- Phosphorylase
- Phosphofructokinase
- Pyruvate Kinase
73
What anagram is used for remembering the 4 key enzymes that regulate glycolysis?
He - Hexokinase
Played - Phosphorylase
Poker - Phosphofructokinase
Poorly - Pyruvate Kinase
74
If Pyruvate converts to acetyl-CoA is it reversible?
- NO
75
When would pyruvate irreversibly convert to acetyl-CoA and enter the citric acid cycle?
- Abundance of Oxygen Present
76
What happens during strenuous physical activity, when energy demands exceed oxygen supply?
- The respiratory chain can't process all hydrogen joined to NADH
77
What is required for the continued release of anaerobic energy?
- NAD+ to oxidize 3-phosphoglyceraldehyde
## Footnote
1-3 diphosphoglycerate is important for making pyruvate
78
How does NAD+ regenerate during anaerobic glycolysis? When would this be required?
How
- Pair of hydrogens from NADH combine with Pyruvate to form Lactate
When
- Energy demands exceed oxygen supply (strenuous physical activity)
79
What are the steps of Lactate formation? What is required? Is it Reversible?
Steps
- 2 hydrogens combine pyruvate
- Catalyzed by lactate dehydrogenase
Required
- Lactate Dehydrogenase Enzyme
Reversible
- YES
80
What happens to lactate formed from pyruvate?
Oxidized By:
- Neighbouring Muscle Fibers
- Heart
- Ventilatory Muscles
Indirect Precursor
- Liver Glycogen
81
Where would lactate form during rest and moderate physical activity?
- Red blood cells (no mitochondria)
- Muscle fibers with high glycolytic activity, and low enzymes
82
What happens once lactate forms in the in the muscle?
Two Routes:
- Diffuse in interstitial space/blood for buffering
- Provides Gluconeogenic substrate for glycogen synthesis
83
What is Gluconeogenesis? What does it result in?
Metabolic pathway
- Generation of glucose from non-carbohydrate carbon substrates
84
What are the two phases of Aerobic Glycolysis?
Phase 1
- Pyruvate from Glycolysis enters kreb cycle
Phase 2
- Electron Transport Chain
85
What happens in Phase 1 of Aerobic Glycolysis?
- Coenzyme A turns Pyruvate into Acetyl-CoA
- Reduced coenzymes (NADH and FADH2) transfer hydrogen to the electron transport chain
86
What happens in Phase 2 of Aerobic Glycolysis?
- Reduced Coenzyme Complexes become oxidized
87
What is the breakdown of ATP yield from Aerobic Glycolysis?
Yield
- 2 ATP Glycolysis
- 2 ATP Citric Acid Cycle
- 28 ATP Oxidative Phosphorylation
88
How much energy does fat supply ?
30-80%
89
What determines the amount of energy used from fat?
- Nutritional Status
- Level of Training
- Intensity/Duration of Physical Activity
90
What is the total energy reserve of fat in a young adult male?
- 60-100k kcal in adipocytes
- 3k kcal stored in intramuscular triacylglycerol
91
What are three specific energy sources from fat catabolism?
- Triacylglycerol stored in muscle near mitochondria
- Triacylglycerols in blood
- free fatty acids in blood
92
Where are circulating triacylglycerols stored?
- Lipoprotein Complexes
93
Where do circulating free fatty acids come from?
Mobilized from triacylglycerol in adipose tissue
94
What is required for the triacylglycerol to split into glycerol ad three fatty acids?
- Lipase Enzyme
95
How many steps does it take for lipid mobilization?
- 7 discrete steps
96
What are the 7 discrete steps of lipid mobilization?
1. Breakdown triacylglycerol to free fatty acid.
2. Transport of Free fatty acids in the blood
3. Uptake of free fatty acids from blood to muscle
4. Preparation of fatty acids for catabolism
5. Entry of activated fatty acids into muscle mitochondria
6. Breakdown of fatty acid to acetyl-CoA via beta oxidation and production of NADH and FADH2
7. Couple oxidation in citric acid cycle and electron transport chain
97
How many ATP molecules does the complete oxidation of triacylglycerol molecules yield?
- 460ATP (depends on # of carbons)
98
What serves as the most plentiful source of potential energy?
- Stored Fat
99
When does fat become the primary energy fuel for exercise and recovery?
Intense, long-duration exercise depletes both blood glucose and muscle glycogen
100
What is the breakdown of ATP Yield from the complete breakdown of a triacylglycerol?
3 Fatty Acids (18-carbon each)
- 147 ATP per
- 147 x 3 = 441
1 Glycerol
- 19 ATP
- 441 + 19 ATP = 460 ATP
101
What pathways do fatty acids utilize for ATP synthesis?
- B-oxidation
- Citric Acid Cycle
102
What pathways do glycerols utilize for ATP synthesis?
- Glycolysis
- Citric Acid Cycle
103
What does it mean that "fat burns in a carbohydrate flame"?
- acetyl-CoA enters citric acid cycle by combing Oxaloacetate to form citrate
- Oxaloacetate breaks down over time
- Pyruvate can create more Oxaloacetate
- Without Oxaloacetate, no break down of Fatty Acids
- Without Pyruvate, no Oxaloacetate
104
How do amino acids enter the energy pathway?
Deamination
- removal of nitrogen
105
How do glucogenic amino acids contribute to energy?
When Deaminated
- yield intermediates for glucose synthesis
106
How do Ketogenic amino acids contribute to energy?
When Deaminated
- yield intermediate actyl-CoA or acetoacetate for TAG formation
107
What provides the vital link between macronutrient energy and chemical energy?
- Citric Acid Cycle
108
What are the metabolic interconversions between carbohydrates and other macronutrients?
- Carbs to lipids (lipogenesis)
- lipids to nonessential amino acids
- proteins to carbs or lipids
109
Which enzyme is required for glycogenolysis
Glycogen phosphorylase
110
how does exercise affect fat metabolism?
* hormone release of epinephrine, norepinephrine, glucagon
* these hormones augment lipase
