Chapter 2 Flashcards
1
Q
What are substrates?
A
fuel sources from which we make energy
2
Q
What are the 3 sources of fuel?
A
carbohydrates, fats, and proteins
3
Q
What are bioenergetics?
A
chemical pathways that convert substrates to energy
4
Q
What level are bioenergetics performed at?
A
the cellular level
5
Q
What is metabolism?
A
chemical reactions in the body
6
Q
How is energy measured in biological systems?
A
calories
7
Q
What does 1 calorie (1 cal) = ?
A
the amount of heat energy needed to raise 1 g of water 1 degree celsius
8
Q
How is energy expressed in humans?
A
kilocalories (kcal)
9
Q
1 kcal = ?
A
1,000 cal, which also = 1 Calorie (dietary)
10
Q
How is energy used in myofibrils?
A
it causes the sliding of actin and myosin filaments resulting in muscle action and force generation
11
Q
When is energy released?
A
when chemical bonds are broken
12
Q
Why is food not used directly for cellular operations?
A
the molecular bonds in substrates are weak and provide little energy when broken
13
Q
How is energy in food’s molecular bonds released?
A
they are chemically released within our cells and then stored in the form of ATP
14
Q
What energy does the body need at rest?
A
50% carbs and 50% fats
15
Q
What substrate provides little energy for metabolism?
A
proteins
16
Q
How do proteins help with energy?
A
important for enzymes that aid chemical reactions and are structural building blocks
17
Q
During intense, short-term exercise, what substrate is being used?
A
more carbs are used
18
Q
During longer, less intense exercise what substrate is being used?
A
more fats and less carbs
19
Q
What percentage of carbs are being used in high intensity exercise?
A
95% CHO
20
Q
What is a major benefit of HIIT training
A
a bigger calorie expenditure compared to continuous exercise
21
Q
What substrate is used more in anaerobic exercise?
A
carbs
22
Q
What substrate is used more in aerobic exercise?
A
fats
23
Q
What are all carbs converted to?
A
glucose
24
Q
How much energy do carbs give you?
A
4.1 kcal/g
25
How many kcals of carbs are stored in the body?
2500 kcals
26
Where is extra glucose stored in the body?
the liver and muscle
27
What is the extra glucose in the liver and muscle called?
glycogen
28
Where is glycogen stored?
in the cytoplasm of muscle cells until those cells use it to form ATP
29
When are muscle and liver glycogen stores limited?
when the diet has an insufficient amount of carbs and can be depleted during prolonged, intense exercise
30
What do we rely on to replenish our carb reserves?
starches and sugars
31
What happens to muscles when there isn't a sufficient carb intake?
muscles are deprived of their primary energy source
32
What energy source is used by brain tissue?
carbs
33
Severe carb depletion causes what in the brain?
negative cognitive effects
34
How do fats contribute to energy?
they provide a large portion of energy used in prolonged, less intense exercise
35
How much energy do fats give you?
9.4 kcals/g
36
How many kcals of fats are stored in the body?
+70,000 kcal stored in the body
37
Why is fat less readily available for cellular metabolism?
it must be broken down to its basic components of glycerol and 3 free fatty acids (FFAs)
38
What is only used in fats to form ATP?
FFAs
39
How does fat have a high net ATP yield?
more energy is derived from breaking down a gram of fat than from the same amount of carbs
40
Why can't fat meet all the energy demands of intense muscular activity?
the rate of energy released from fat is too slow
41
When is protein used as an energy source?
in the case of severe energy depletion
42
What does protein need to be converted to before it produces energy?
glucose
43
What is gluconeogenesis?
when protein or fat is converted into glucose
44
What is lipogenesis?
the process of converting protein into fatty acids
45
Why is lipogenesis used?
for energy storage and cellular energy substrate
46
What percentage of energy can protein supply to the body to sustain prolonged exercise?
10%
47
What basic unit of protein can be used for energy?
amino acids
48
How much energy does protein give you?
4.1 kcal/g
49
Free energy has to be released from what?
chemical compounds at a controlled rate
50
What is the controlled rate determined by?
the availability of the primary substrate and enzyme activity
51
What does the availability of a substrate do for the controlled rate?
it increases the activity of that particular pathway
52
What is mass action effect?
the influence of substrate availability in the rate of metabolism
53
What is catabolism?
enzymes speeding up the breakdown of chemical compounds
54
How do enzymes speed up reactions?
by lowering the activation energy required to begin the chemical reaction
55
Most enzymes end with what suffix?
-ase
56
What enzyme breaks down ATP and releases stored energy?
ATPase
57
Each step in a biochemical pathway requires what?
to be catalyzed by a specific enzyme
58
What happens when there is an increase in enzyme activity?
an increased rate of product through a metabolic pathway
59
What is a rate limiting enzyme?
an enzyme in a metabolic pathway in control of the reaction's overall rate
60
What is the activity of a rate limiting enzyme determined by?
the accumulation of substances down the pathway that decreases enzyme activity through negative feedback
61
Negative feedback is like what for ATP?
it's like a thermostat. it either kicks on or kicks off ATP
62
What is the immediately available source of energy for almost all bodily functions?
ATP
63
What is an ATP molecules composed of?
adenosine and 3 inorganic phospate (Pi) groups
64
How is ATP broken down to release energy?
ATP molecules combine with water and are acted on by ATPase then the last phosphate group splits away, rapidly releasing free energy
65
What is phosphorylation?
when a phosphate group (Pi) is added to a low energy ADP to generate ATP
66
What is substrate-level phosphorylation?
when ATP is generated without oxygen availability
67
What is oxidative phosphorylation?
when ATP is generated with oxygen
68
How much ATP can cells store?
only limited amounts of ATP because it must constantly generate new ATP to provide energy
69
What three metabolic pathways do cells use to generate ATP?
the ATP-PCr system, the glycolytic system, and the oxidative system
70
What metabolic pathway systems are anaerobic?
the ATP-PCr system and glycolytic system
71
What metabolic pathway system is aerobic?
the oxidative system
72
What muscle fibers use the ATP-PCr system?
type 2a/2b
73
What is the ATP-PCr's energy system?
phosphocreatine (PCr)
74
What substrate does the glycolytic system use?
carbohydrates
75
What substrate does the oxidative system use?
carbs and fats
76
What is phosphocreatine?
a high energy molecule that stores energy
77
How does PCr help create energy?
phosphocreatine (PCr) donates a phosphate (Pi) group to ADP to form ATP
78
Energy released by the breakdown of PCr does what to ATP?
it regenerates ATP to maintain a constant supply under resting conditions
79
What enzyme catalyzes PCr to release energy?
creatine kinase (CK)
80
What happens to CK when ATP levels are down?
CK activity is up
81
What happens to CK when ATP levels are high?
CK activity is down
82
What happens to CK when exercise progresses and ATP is being generated by the other two systems?
CK activity is inhibited
83
What is the ATP-PCr system classified as?
substrate-level metabolism
84
What is the ATP yield in the ATP-PCr system?
1 mol ATP/1 mol PCr
85
What is the duration of the ATP-PCr system?
3-15 sec
86
What happens at exhaustion of the ATP-PCr system?
both ATP and PCr levels are low and unable to provide energy for further muscle contraction and relaxation
87
What does the glycolytic system use as its substrate?
glucose or glycogen
88
Why is the glycolytic system glycolytic?
it entails glycolysis
89
What is glycolysis?
the breakdown of glucose through a pathway that involves a sequence of glycotic enzymes
90
How is ATP produced in the glycolytic system?
the system involves the liberation of energy through the breakdown of glucose
91
Where does blood glucose come from?
from the digestion of carbs and breakdown of liver glycogen
92
What is glycogenesis?
when glycogen is synthesized from glucose and stored in the liver or muscle until needed
93
What is glycogenolysis?
when glycogen is broken down to glucose-1-phosphate and enters a glycolysis pathway
94
When can glucose or glycogen be used to generate energy?
after it's been converted to glucose-6-phosphate
95
How long does the glycolytic system last?
15 seconds to 2 minutes
96
When does glycolysis begin?
when glucose-6-phosphate is formed
97
What does glycolysis require to breakdown glycogen?
10-12 enzymatic reactions for the breakdown of glycogen to pyruvic acid, which is then turned to lactic acid
98
Where does glycolysis take place?
the cell cytoplasm
99
What is the net gain from glycolysis if glycogen is used?
3 mol of ATP for each mole of glycogen broken down
100
What is the net gain from glycolysis if glucose is used?
2 mol of ATP for each mole of glucose broken down
101
Why is the net gain different if glucose is used?
1 mol of ATP was used to convert glucose to glucose-6-phosphate
102
Does the glycolytic system produce large amounts of ATP?
no
103
What is a limitation to the glycolytic system?
it causes an accumulation of lactic acid in the muscles and body fluids
104
How does the glycolytic produce lactic acid?
glycolysis produces pyruvic acid and without oxygen, the pyruvic acid is converted to lactic acid
105
In all-out sprints, how much can lactic acid increase in the glycolytic system?
it can increase from a resting value of 1 mmol/kg to more than 25 mmol/kg
106
What is the rate-limiting enzyme in the glycolytic pathway?
Phosphofructokinase (PFK)
107
What happens to PFK activity when ATP is low?
it increases and speeds up glycolysis
108
What happens to PFK activity when ATP activity is high?
it decreases and slows down glycolysis
109
What feeds back to inhibit PFK in glycotic pathways?
products of the Krebs cycle
110
What system produces low ATP?
ATP-PCr system
111
What system produces moderate ATP?
glycolytic system
112
What system produces the most ATP?
oxidative system
113
How does the oxidative system generate energy?
by the body breaking down substrates with the aid of oxygen ... AKA cellular respiration
114
Where does the oxidative production of ATP occur?
in the mitochondria
115
What system is the most complex out of the three bioenergetic systems?
the oxidative system which is why it takes the longest
116
What substrate does oxidative energy production come from?
carbohydrates (starting with glycolysis) or fats
117
What 3 stages are involved in oxidative production of ATP from carbohydrates?
stage 1: glycolysis, stage 2: the kreb's cycle, stage 3: the electron transport chain
118
In the presence of oxygen during glycolysis, what is pyruvic acid converted into?
acetyl coenzyme A (acetyl CoA)
119
What does the presence of oxygen determine in glycolysis?
the end fate of pyruvic acid
120
What is the ATP yield of glycolysis in the oxidation of carbohydrates?
the same ATP yield as anaerobic glycolysis whether its glycogen or glucose
121
How does glycolysis in the oxidation of carbohydrates differ from anaerobic glycolysis?
in the presence of oxygen, the pyruvic acid goes to the kreb's cycle
122
How does the pyruvic acid get to the kreb's cycle in glycolysis?
the pyruvic acid converts to acetyl-CoA then enters the kreb's cycle
123
What is the Kreb's cycle?
a series of chemical reactions that permit the complete oxidation of acetyl-CoA
124
How many molecules of pyruvate are formed for every glucose molecule in the kreb's cycle?
2 molecules of pyruvate
125
In the presence of oxygen, each glucose molecule results in how many complete kreb's cycles?
2 complete kreb's cycles
126
What is guanosine triphosphate (GTP)?
a high energy compound similar to ATP
127
How is guanosine triphosphate (GTP) generated in the Kreb's cycle?
the conversion of succinyl CoA to succinate in the Kreb's cycle generates GTP
128
How does GTP form ATP?
GTP transfers a phosphate group (Pi) to ADP to form ATP
129
What are the results at the end of the Kreb's cycle?
2 additional moles of ATP are formed and the carbohydrate is broken down into carbon dioxide and hydrogen
130
What happens when too many hydrogen ions are in the cell?
the cell becomes too acidic
131
What happens to the hydrogen ions released during the Kreb's cycle?
they're moved to the electron transport chain
132
How is NAD and FAD produced in the Kreb's cycle?
1 pyruvate contains 3 NAD and 1 FAD per cycle
133
What is created at the end of a Kreb's cycle?
3 NADs, 1 FAD and 1 ATP is created each cycle
134
What carries hydrogen atoms to the electron transport chain?
NADH and FADH
135
What chain does hydrogen travel down in the electron transport chain?
a proton pump, ATP synthase, then concentration gradients
136
What happens as hydrogen ions move down the concentration gradient?
energy is transferred to ADP and ATP is formed through ATP synthase
137
How many molecules of ATP are formed for every pair of electrons brought to the transport chain by NADH?
2.5 molecules of ATP per NADH
138
How many molecules of ATP are formed for every pair of electrons brought to the transport chain by FADH?
1.5 molecules of ATP per FADH
139
How many molecules of ATP can complete oxidation of glucose generate?
32 molecules of ATP
140
How many molecules of ATP can complete oxidation of glycogen generate?
33 molecules of ATP
141
What are triglycerides?
a major fat energy source
142
Where are triglycerides stored?
in fat cells and between/within skeletal muscle fibers
143
What has to happen to a triglyceride before it's used for energy?
it has to broken down to one molecule of glycerol and 3 free fatty acid (FFA) molecules
144
What is lipolysis?
the break down of triglycerides
145
What is the primary energy source for fat metabolism?
free fatty acids (FFA)
146
What does the rate of FFA entry depend on?
concentration gradient
147
Fats yield how much more ATP than glucose?
3 to 4 times more ATP
148
What is beta-oxidation (B-oxidation) of fats?
the process of converting FFAs to acetyl-CoA
149
How many acetyl-CoA enzymes are yield by 16-carbon FFA?
8 acetyl-CoA enzymes
150
What is needed to activate B-oxidation?
an input energy of 2 ATPs
151
How much ATP is produced by fats?
it depends on the specific fat oxidized
152
What regulates the kreb's cycle?
negative feedback
153
What is the rate limiting enzyme in the kreb's cycle?
isocitrate dehydrogenase
154
What does isocitrate dehydrogenase do?
regulates the electron transport chain
155
In what circumstance is protein used for energy?
starvation
156
What can protein be converted to?
glucose through gluconeogenesis or pyruvate/acetyl-CoA
157
Why is protein's energy yield hard to determine?
protein contains nitrogen and some nitrogen can't be oxidized in the body
158
What are 3 reasons why lactic acid is not bad?
it stays local, lactate shuttle, and the cori cycle
159
What can happen to lactate produced in the cytoplasm?
it can be taken up by the mitochondria within the same fiber and be oxidized
160
What is lactate shuttle?
transporting lactate away from its site of production and using it elsewhere
161
What is the cori cycle for lactate?
when lactic acid is transported by blood to the liver and turned into pyruvic acid then glucose and transported back to the working muscle
162
When a person exercises at the highest intensity possible, what are the 3 energy systems doing?
each of the systems contribute to the total energy needs of the body
163
What is the crossover point?
the intensity where fat and carbohydrate use intersects
164
What is the crossover point affected by?
exercise intensity and endurance training status
165
What is a benefit of life long endurance training?
increased capacity for fat oxidation to produce ATP during exercise
166
What determines oxidative capacity?
a muscle's fiber type composition
167
Type 2 muscle fibers are better suited for what type of energy production?
glycolytic
168
What does endurance training do for type 2 muscle fibers?
it enhances their oxidative capacity
169
Why should people with large percentages of type 2 fibers do endurance training too?
it can increase their muscles' aerobic capacities
170
What does oxidative metabolism depend on?
adequate supply of oxygen
171
As exercise intensity increases, what does energy demands do?
energy demands increase
172
What is the function of brown adipose tissue?
to transfer energy from food directly to heat and increase metabolism
173
What is the uncoupling protein in brown fat?
it uncouples the electron transport chain from the creation of ATP
