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
What ways can the mitochondria produce ATP?
A
- Citric Acid Cycle
- Respiratory Chain (Aerobic)
- Pyruvate from glucose
- Some deaminated amino acids
9
Q
What ways for ATP production occur in the Cytosol?
A
- Glycolysis (Anaerobic)
- Phosphocreatine
- Glucose/Glycogen
- Glycerol
- Some Deamniated Amino Acids
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
17
Q
Where does most energy for phosphorylation derive from?
A
- Carbohydrates
- Lipids
- Protein
18
Q
What do oxidation reactions do?
A
- Donate electrons
19
Q
What do Reduction reactions do?
A
- Accept Electrons
20
Q
What constitutes the biochemical mechanism that underlies energy metabolism?
A
- RedOx Reactions (oxidation - reduction)
21
Q
What do redox reactions provide from catabolism of stored macronutrients?
A
- Hydrogen Atoms
22
Q
What are the energy factories in the mitochondria? What do they do?
A
What
- Carrier Molecules
Do
- Remove electrons from hydrogen (oxidation)
- Pass them to oxygen (reduction)
- Synthesis ATP
23
Q
Are hydrogen atoms turned loose in intracellular fluids during cellular oxidation?
A
- NO
24
Q
What catalyze’s hydrogen’s release from the nutrient substrate?
A
- substrate-specific dehydrogenase enzymes
25
What accepts pairs of electrons from hydrogen?
- coenzyme component of the dehydrogenase
26
What happens when Nicotinamide Adenine Dinucleotide (NAD+) gains hydrogen and two electrons?
-Reduces to NADH
27
What happens to the other Hydrogen when one pairs with NAD+?
- Appears in the cell fluid as H+
28
How many electrons does Flavin Adenine Dinucleotide accept?
- Two
29
What are NAD+ and FAD?
- Electron Acceptors
30
What are Cytochromes?
- A series of Iron-protein electron carriers dispersed on the inner membranes of the mitochondrion
31
What is a bucket brigade?
- Passing of electrons carried by NADH and FADH2 down the Cytochromes
32
What represents the final common pathway where electrons extracted from hydrogen pass to oxygen?
- Electron Transport
33
What drives the respiratory chain? How?
Oxygen
- serving as final electron acceptor to combine with hydrogen to form water
34
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
35
What is released during the passage of electrons down the chain?
- Enough energy to re-phosphorylate ADP to ATP`
36
How does oxidative phosphorylation synthesize ATP?
- Transfer of electrons from NADH and FADH2 to oxygen
37
How much ATP synthesis occurs in the respiratory chain by oxidative reactions coupled with phosphorylation?
- 90%
38
How many coupling sites during the electron transport does energy transfer from NADH to ADP to reform ATP?
- three distinct places
39
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
40
What is the result of shuttling hydrogen in the electron transport chain requiring energy?
On Average
- NADH produces 2.5 ATP
- FADH2 produces 1.5 ATP
41
How much energy does 1 mole of ATP formed from ADP + P conserve?
- 7kcal energy
42
What is the relative efficiency level for harnessing chemical energy via the electron transport oxidative phosphorylation?
- 34%
43
What is created by electron transport energy-releasing reactions in the mitochondria?
- Proton (H+) gradient across the inner mitochondrial membrane
44
What provides the electrochemical basis for coupling electron transport to oxidative phosphorylation to form ATP?
- Stored energy in the inner mitochondrial membrane
45
What 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
46
What are the 6 fuel sources?
- Phosphocreatine
- Anaerobic Glycolysis
- Blood Glucose
- Triacylglycerol and Glycogen Molecules
- Free Fatty Acids
- Carbon Skeleton of Amino Acids
47
What controls the phosphorylation of ADP from PCr?
Enzyme Control
- Creatine Kinase
- Adenylate Kinase
48
Where are triacylglycerol's stored?
- Within Muscle Cells
49
Where are the carbon skeletons of amino acids located?
- Intramuscular
- Liver-derived
50
What is the only macronutrient substrate whose stored energy generates ATP without oxygen?
- Carbohydrates
51
What is required for processing a large quantity of fat for energy?
- minimal carbohydrate breakdown
52
What aerobic breakdown occurs faster, Carbs or Fats?
- Carbs
53
What requires an uninterrupted supply of carbs to function properly?
- The central nervous system
54
If we received 100% of energy from 1 full glucose, how much energy would we get?
- 686 kcal
55
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
56
What happens to the rest of the potential energy after the breakdown of glucose?
- Dissipated as heat
57
What are the two forms of carbohydrate breakdown?
- Anaerobic Glycolysis
- Aerobic Glycolysis
58
How much energy is released from Anaerobic Glycolysis of Glucose?
- 5%
59
What results from the Anaerobic Glycolysis of Glucose?
- pyruvate-to-lactate formation
- Release of 5% energy
60
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
61
What is the First Step of Anaerobic Glycolysis?
- Glucose to Glucose 6-phosphate
62
What does the conversion of Glucose to Glucose-6-phosphate require?
- 1 ATP
- Hexokinase Enzyme
63
What does the Enzyme Hexokinase catalyze?
- Glucose to Glucose-6-phosphate
64
What is not required to convert Glycogen to Glucose-6-phosphate?
- ATP
- Hexokinase Enzyme
65
Where does Glycolysis take place?
- Cytosol
66
What does Glucose break down into following Glycolysis? What does it net?
- 2 Pyruvates
- Gains 2 ATP
67
What does Glycogen break down into following glycolysis? what does it net?
- 2 Pyruvates
- Gain 3 ATP
68
What is Glycogenesis?
- Glycogen Synthesis
69
Explain Glycognesis
Glycogen Synthesis
- Surplus Glucose forms Glycogen
- Occurs in low cellular activity
- Facilitate by Glycogen Synthase
- Glucose links to large Glycogen molecules
70
What is Glycogenolysis?
- Glycogen Breakdown
71
Explain Glycogenolysis.
Glycogen Breakdown
- Glycogen breakdown to glucose
- occurs in high cellular activity with glucose depletion
- Requires Glycogen Phosphorylase
72
What regulates Glycolysis?
- Levels of substrate fructose 1,6-diphosphate
- high oxygen inhibits
- Concentration of 4 enzymes
73
What 4 enzymes regulate Glycolysis?
- Hexokinase
- Phosphorylase
- Phosphofructokinase
- Pyruvate Kinase
74
What anagram is used for remembering the 4 key enzymes that regulate glycolysis?
He - Hexokinase
Played - Phosphorylase
Poker - Phosphofructokinase
Poorly - Pyruvate Kinase
75
If Pyruvate binds to acetyl-CoA is it reversible?
- NO
76
When would pyruvate irreversibly bind to acetyl-CoA and enter the citric acid cycle?
- Abundance of Oxygen Present
77
What happens during strenuous physical activity, when energy demands exceed oxygen supply?
- The respiratory chain can't process all hydrogen joined to NADH
78
What is required for the continued release of anaerobic energy?
- NAD+ to oxidize 3-phosphoglyceraldehyde
79
How does NAD+ regenerate during anaerobic glycolysis? When would this be required?
How
- Pair of hydrogens combines with Pyruvate to form Lactate
When
- Energy demands exceed oxygen supply (strenuous physical activity)
80
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
81
What happens to lactate formed from pyruvate?
Oxidized By:
- Neighbouring Muscle Fibers
- Heart
- Ventilatory Muscles
Indirect Precursor
- Liver Glycogen
82
Where would lactate form during rest and moderate physical activity?
- Red blood cells (no mitochondria)
- Muscle fibers with high glycolytic activity, and low enzymes
83
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
84
What is Gluconeogenesis? What does it result in?
Metabolic pathway
- Generation of glucose from non-carbohydrate carbon substrates
85
What are the two phases of Aerobic Glycolysis?
Phase 1
- Pyruvate from Glycolysis
Phase 2
- Electron Transport Chain
86
What happens in Phase 1 of Aerobic Glycolysis?
- Coenzyme A turns Pyruvate into Acetyl-CoA
- Reduced coenzymes transfer hydrogen to the electron transport chain
87
What happens in Phase 2 of Aerobic Glycolysis?
- Reduced Coenzyme Complexes become oxidized
88
What is the breakdown of ATP yield from Aerobic Glycolysis?
Yield
- 2 ATP Glycolysis
- 2 ATP Citric Acid Cycle
- 28 ATP Oxidative Phosphorylation
89
How much energy does fat supply ?
30-80%
90
What determines the amount of energy used from fat?
- Nutritional Status
- Level of Training
- Intensity/Duration of Physical Activity
91
What is the total energy reserve of fat in a young adult male?
- 60-100k kcal in adipocytes
- 3k kcal stored in intramuscular triacylglycerol
92
What are three specific energy sources from fat catabolism?
- Triacylglycerol stored in muscle mitochondria
- Triacylglycerols in blood
- free fatty acids in blood
93
Where are circulating triacylglycerols in?
- Lipoprotein Complexes
94
Where do circulating free fatty acids come from?
Mobilized from triacylglycerol in adipose tissue
95
What happens prior to energy being released from fat?
- Hydrolysis in the cell's cytosol splits triacylglycerol into glycerol and three fatty acids
96
What is required for the triacylglycerol to split into glycerol ad three fatty acids?
- Lipase Enzyme
97
How many steps does it take for lipid mobilization?
- 7 discrete steps
98
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 from blood to muscle
5. Entry of activation 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
99
How many ATP molecules does the complete oxidation of triacylglycerol molecules yield?
- 460ATP (depends on # of carbons)
100
What serves as the most plentiful source of potential energy?
- Stored Fat
101
When does fat become the primary energy fuel for exercise and recovery?
Intense, long-duration
- depletion of both blood glucose and muscle glycogen
102
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
103
What pathways do fatty acids utilize for ATP synthesis?
- B-oxidation
- Citric Acid Cycle
104
What pathways do glycerols utilize for ATP synthesis?
- Glycolysis
- Citric Acid Cycle
105
What does it mean that "fat burns in a carbohydrate flame"?
- Oxaloacetate required for citric acid cycle
- Oxaloacetate breaks down over time
- Glucose to Pyruvate can create more Oxaloacetate
- Without Oxaloacetate, no break down of Fatty Acids
- Without Pyruvate, no Oxaloacetate
106
How do amino acids enter the energy pathway?
Deamination
- removal of nitrogen
107
How do glucogenic amino acids contribute to energy?
When Deaminated
- yield intermediates for glucose synthesis
108
How do Ketogenic amino acids contribute to energy?
When Deaminated
- yield intermediate actyl-CoA or acetoacetate for TAG formation
109
What provides the vital link between macronutrient energy and chemical energy?
- Citric Acid Cycle
110
What are the metabolic interconversions between carbohydrates and other macronutrients?
Carbs to lipids
- lipogenesis
carbs to nonessential amino acids
111
What are the metabolic interconversions between fats and other macronutrient substrates?
Lipids convert to nonessential amino acids
112
What are the metabolic interconversions between proteins and other macronutrient substrates?
Protein convert to
- carbs
- Lipids
113
