Chapter 6: Bioenergetics Flashcards
1
Q
What is the molecular structure of ATP?
A
Adenine and ribose attached to three phosphates.
2
Q
How does ATP store and release energy?
A
The two bonds between the three phosphates store energy, and release energy when broken
3
Q
What is the law that states that energy can be changed from one form to another but cannot be created or destroyed?
A
The first law of thermodynamics
Law of conservation of energy
4
Q
What metabolic reactions are the cornerstone of human physiology?
A
Anabolic: the building process
Catabolic: The breakdown process
5
Q
What is the enzyme that breaks the bond between the second and third phosphates to release the stored energy?
A
ATPase
6
Q
What is dephosphorylation?
A
The process of removing a phosphate using water
7
Q
How many acidic protons are released during the breakdown of ATP to ADP?
A
one
8
Q
What is rephosphorylation?
A
The process of reattaching or adding a phosphate (Pi)
9
Q
What enzyme is needed for rephosphorylation?
A
ATP synthase
10
Q
What’s the process of breaking of ATP while in the presence of water to release energy stored within its bonds?
A
ATP hydrolysis
11
Q
What is metabolic acidosis? What is it caused by?
A
When ATP hydrolysis causes the muscle to accumulate protons (H+) faster than the muscle can remove them as waste
12
Q
What is the short-term effect of metabolic acidosis?
A
Impairs muscle power and energy production
13
Q
What happens to cellular ph during acidosis?
A
It becomes lower
14
Q
When happens with ADP to AMP?
A
the two remaining phosphate ions in the ADP bond can be used to generate cellular energy
15
Q
What is the enzyme that converts two ADP into one ATP?
A
adenylate kinase
16
Q
What is the chemical reaction for AMP to ADP?
A
AMP + Pi + energy
Pi is a phosphate ion
17
Q
Why is AMP is not an ideal molecule to have in the cells?
A
An accumulation of phosphates can cause muscle fatigue and limit physical performance
It can also break down even further and create ammonia, which is toxic
18
Q
What’s the advantage of burning a higher percentage of stored fat as fuel?
A
It does not result in cellular acid buildup
19
Q
What are the 3 energy systems?
A
The phosphagen system
Anaerobic glycolysis
Aerobic glycolysis
20
Q
What is the phosphagen system?
A
The combination of a muscle’s stored ATP plus its phosphocreatine, used to create up to 30 seconds’ worth of energy
21
Q
What is the molecule found in muscle and brain tissue that donates its phosphate to ADP to form ATP during the phosphagen system?
A
Phosphocreatine
22
Q
What is anaerobic glycolysis?
A
Producing ATP from glucose
23
Q
What us glucose? What is it used for?
A
The smallest molecule a carbohydrate can be broken down into and used as an energy source
24
Q
What is pyruvate?
A
A three-carbon structure formed by splitting a glucose molecule
25
Why does anaerobic glycolysis produce a decline in muscle power?
From a production of protons (H+) that increase cellular acidity
26
What is the end product of glycolysis?
Lactic acid
27
What is aerobic glycolysis?
The breakdown of fuels to form ATP in the presence of oxygen
28
What is the gel-like material that makes up all inner components of every cell within the human body?
Cytoplasm
29
What is sarcoplasm?
The cytoplasm of a muscle cell
30
What is the cell nucleus?
An organelle that controls a cell and the deoxyribonucleic acid (DNA)
31
What is deoxyribonucleic acid (DNA)?
A molecule that contains genetic instructions for growth, development, reproduction, and functioning
32
What's the only part of the cell that is not considered part of the cytoplasm?
The nucleus
33
What is the chemical structure of phosphocreatine?
One phosphate molecule connected to one molecule of creatine
34
What molecule assists in the re-formation of ATP from ADP?
Creatine
35
How does creatine work?
It donates its phosphate to ADP to form ATP
36
What enzyme that catalyzes ADP to ATP, as well as creatine to phosphocreatine?
Creatine kinase
37
Why is the creatine kinase reaction critical for muscular contraction?
It keeps the ATP-ADP cycle running
38
What happens the longer the creatine kinase reaction runs?
More protons will build up in the cytoplasm, reducing the cellular pH of the cell and leading to metabolic acidosis
39
What is the limitation on the phosphagen system?
The supply of phosphocreatine in the body
40
Where is creatine synthesized?
In the kidney, pancreas, and the liver
41
What does the supplementation of creatine allow?
More stored creatine in the cells
complements the phosphagen system
Helps delay muscle fatigue and increase muscular output for short-duration efforts
42
Why can a more conditioned individual replenish cellular phosphocreatine within 5–10 minutes?
They are generally able to take in and use oxygen better than an unconditioned individual
43
What is the limitation on the replenishment of stored phosphocreatine?
The availability of oxygen
44
What is glycogen?
The stored form of glucose in liver and skeletal muscle
45
What happens when stored glycogen runs low?
glucose in the bloodstream is forced into the muscle cells and broken down (aka glycolosis)
46
What processes produce many times more ATP than the phosphagen system?
Aerobic or anaerobic glycolysis
47
What are the glyocolytic processes in the absence and presence of oxygen?
In the presence of oxygen: oxidative phosphorylation
In the absence of oxygen: anaerobic glycolysis
48
What happens to the glucose molecule during anaerobic glycolosis?
Its split into two pyruvate molecules
49
What coenzyme regulates the split between two pyruvate molecules?
nicotinamide adenine dinucleotide (NAD+)
50
What is the reduced form of NAD+ that necessary for energy production that comes from glycolysis?
NADH
51
What causes “muscle burn”?
The buildup of lactate and protons when the phosphagen system is phasing into anaerobic metabolism
52
What causes a decrease in muscular output during high intensity activities?
The inability to allow enough oxygen to enter the mitochondria for the exercise to be predominantly aerobic
53
What 3 conditions produce larger quantities of lactate?
- Lack of oxygen in the mitochondria
- Quick increase in exercise intensity
- Recruitment of type II muscle fibers
54
What are the three primary benefits to the muscles of lactate?
acts as a buffer to slow acidosis
cotransporter from the sarcoplasm and the bloodstream, taking a proton along with it
can be transported to the liver and converted back into glucose through the lactic acid cycle
55
What is gluconeogenesis?
The formation of glucose from noncarbohydrate sources, usually in the liver
56
What is the the preferred source of energy for the cardiac muscles of the heart?
lactate
57
What are the conditions under which lactate is used?
- Normal resting heart activity
| - Submaximal exercise (~40–60 percent of VO2 max)
58
What happens when intensity is increased to around 55 to 65 percent of a person’s VO2 max?
The rate of lactate accumulation exceeds the muscle’s ability to clear it aka the lactate threshold
59
What does the lactate threshold signal?
The physiological point where the central nervous system and muscle fibers will be affected by the excess of protons because lactate cannot be buffered
60
What causes lactate to rise, and corresponds with an increase in H+ and blood acidity?
Increasing power output (i.e., work rate)
61
What are the by-products of anaerobic glycolysis in cellular energy production?
Lactate and H+
62
What happens as acidosis causes an increase in lactate concentration and free protons?
Declines in muscular performance and increases in muscle soreness
63
How can acidosis (and the associated muscle soreness) be minimized?
With an appropriate recovery intensity between bouts of high-intensity exercise
64
Why is it a light run after a sprint a good idea?
Because when recovery is near or at the individual’s lactate threshold, optimal lactate and proton clearance from the sarcoplasm and the blood occurs
65
why is anaerobic glycolysis effective only for high-intensity activities of a relatively short duration?
because In the absence of oxygen, only 2 ATP molecules are produced for each molecule of glucose
66
What affects the exact timing of oxidative phosphorylation taking over as the energy system?
- The conditioning of the individual
- Highly trained athletes can access their aerobic metabolism at full capacity in 60 seconds
- Unconditioned individuals may take up to 4 minutes to become completely aerobic
67
What is aerobic metabolism?
The breakdown of fuels to form ATP in the presence of oxygen
68
What is acetyl coenzyme A (acetyl-CoA)?
The central metabolite that initiates the aerobic metabolism process within the mitochondria, regardless of fuel source
69
What is the the first stage of aerobic metabolism?
The Krebs Cycle
70
What is the metabolic pathway within mitochondria where the majority of ATP molecules are formed during aerobic metabolism?
electron transport chain
71
What's another name for the electron transport chain?
Oxidative phosphorylation
72
What are the three reasons mitochondria are essential for maintaining performance?
1) They produce ATP during exercise, especially when the activity lasts more than a few minutes
2) During the first 10 to 30 seconds of maximal activity, mitochondria absorb protons (H+)
3) mitochondria help athletes recover more quickly between intermittent bursts of powerful activity
73
How do strength training and cardiovascular training positively affect the mitochondria?
Strength training increases the the organelle’s ability to produce ATP
Cardiovascular training increases substrate concentrations and increases in the number of mitochondria in each cell
74
What are the 4 fuel sources for aerobic metabolism?
Glucose, fatty acids, lactate, and ketones
75
What are the 3 locations that fat is stored around the body?
Visceral fat - around the midsection, in the area between the abdominals and organs
Subcutaneous fat - directly beneath the skin
Intramuscular fat
76
What are triglycerides?
The stored form of fatty acids
77
What is lipolysis?
The breakdown of triglycerides into fatty acids to be used for energy
78
What roles does the hormone epinephrine (adrenaline) play during exercise?
It attaches to receptors on fat cells, which breaks down triglycerides into fatty acids
Allows them to flow into the blood, which transports them to the muscles
79
How do fatty acids reach the muscle cell?
They move into the sarcoplasm and then into the mitochondria
80
What is beta-oxidation (β-oxidation)?
The process of transforming fatty acids into acetyl-CoA
81
What are the two ways lactate can be used for energy?
Remain in the muscle
| Move to other areas
82
What happens when lactate remains in the muscle?
It converts back to pyruvate and then enters the mitochondria to produce ATP
83
How does lactate move through the body?
It enters the bloodstream and flows into another working muscle, including the heart or the liver
84
What happens when lactate enters the liver?
It’s converted to pyruvate, then to glucose, and then sent back through the bloodstream to wherever it’s needed
85
What are ketones?
An acidic by-product of fatty acid metabolism, produced in the liver when glucose isn’t available
86
What hormones control ketones?
insulin and glucagon
87
What is insulin?
A hormone produced in the pancreas that regulates the metabolism of carbohydrates, fats, and proteins
88
What is glucagon?
hormone produced in the pancreas that increases levels of glucose and fatty acids in blood
89
What conditions force the liver to metabolize large amounts of fatty acids?
starvation, a severe illness or infection, or a chronic disease like diabetes
90
What happens if ketones remain elevated too long?
It can lead to ketoacidosis, a potentially fatal health problem
91
During exercise, ketones don’t typically play a significant role in ATP production. But when will they will have an effect?
A diet very low in carbohydrates
An ultralow calorie diet
An ultramarathon or another extreme endurance event
92
What percent of the brain's ATP needs do ketones meet after 3 days and then several weeks without carbs?
30 and 70
93
Regardless of the fuel source, acetyl-CoA is the central metabolite that . . .
initiates the aerobic metabolism process within the mitochondria
94
The Krebs cycle is also referred to as the . . .
citric acid cycle
95
How many steps are in the citric acid cycle?
Eight
96
What are crucial products that contribute electrons to aerobic metabolism?
NADH and FADH2
97
What is the electron transport chain?
The stage where most of the ATP (32) is produced in aerobic metabolism
98
What happens during rephosphorylation?
The additional phosphate is broken down again for quick energy as part of the ATP-ADP cycle
99
What happens to the glucose molecule during anaerobic glycolosis?
It is split into a pair of pyruvate molecules to produce two ATP
100
Where is creatine found, and what do average stores depend upon?
Creatine is naturally found in muscle tissue
Average stores maintained will depend on overall muscle mass
101
Where is creatine synthesized?
in the liver and kidneys
102
What amino acids synthesize creatine?
methionine, glycine, and arginine
103
What is the long-term effect of metabolic acidosis?
Reprograms the cell to recycle ADP faster and reduce the oxidative stress of the process
104
What happens when lactate enters the liver and it’s not needed?
the glucose is converted to glycogen and stored in the muscles or liver to fuel future activity
105
What is the muscle’s primary potential source of H+ accumulation?
ATP hydrolysis
106
What is the goal of endurance training?
To develop the body’s ability to use stored fat as the primary fuel source, since fat provides a virtually limitless supply of energy
107
What happens as ATP-ADP cycle keeps running?
More protons build up in the cytoplasm, reducing the pH of the cell
108
How long does Full replenishment of stored phosphocreatine take after maximum effort exercise?
15–25 minutes
109
What is the currency of the human body that allows it to continually function?
Adenosine triphosphate (ATP)
110
How much ATP can the human body store?
Very little. Skeletal muscles have enough stored ATP to contract vigorously for just one or two seconds
111
What is muscle’s second fastest source of ATP?
Glucose
When stored glycogen runs low, glucose in the bloodstream is forced into the muscle cells and broken down in a process called glycolysis
