Module 7 - Energy Metabolism Flashcards
(127 cards)
1
Q
True or False?: total amount of energy in a system cannot be created or destroyed
A
True, but it can be transformed from one form to another
2
Q
What is metabolism?
A
chemical processes by which human body converts food into usable energy
- the kcal giving food mix with O2 to make energy; byproducts are CO2 and HO2
3
Q
What is anabolism?
A
process of building larger molecules from smaller ones
4
Q
What is catabolism?
A
process of breaking down larger molecules into smaller ones (glucose into H2O and CO2), resulting in release of energy
5
Q
In normal nutrient catabolism, human cells rely on
A
glucose, fat and protein metabolism
6
Q
What is a metabolic pathway?
A
a reaction that brings raw material to final product (eg. ATP)
7
Q
Glucose, fatty acids and amino acids can be broken down to:
A
- provide energy (ATP)
- transformed into energy-storage molecules
- synthesize structural or regulatory molecules
8
Q
ATP stands for
A
Adenosine Triphosphate
9
Q
How does ATP contribute to energy?
A
when enzyme breaks bond between phosphates of ATP a lot energy of energy is released
10
Q
How is Adenosine Diphosphate turned back into ATP?
A
Phosphorylation (requires energy)
11
Q
Energy from catabolism of food forms __ which is broken down and releases energy to power cellular work
A
ATP
12
Q
Where does ATP synthesis occur?
A
Mitochondria
13
Q
Metabolic pathways require ___!
A
O2
14
Q
Describe path of O2
A
ventilation>lung diffusion>cardiac output>O2 transport within blood>muscle diffusion
15
Q
When there is adequate oxygen what type of metabolism occurs?
A
aerobic metabolism (oxidation of glucose to produce ATP)
16
Q
When there is inadequate oxygen what type of metabolism occurs?
A
anaerobic metabolism
17
Q
What is the first step of oxidation of glucose to produce ATP, which occurs outside the cell (without oxygen)?
A
Glycolysis
18
Q
What does glycolysis start with and produce at the end?
A
Starts with 6-carbon glucose and produces 2 3-carbon pyruvate
19
Q
In anaerobic respiration, the 2 3-carbon pyruvates are converted to what outside the mitochondria?
A
2 3-carbon Lactic acid which becomes Lactate when H+ released
20
Q
After releasing hydrogen, where does Lactate go?
A
enters the blood stream and is taken to liver which converts it to glucose via cori cycle / or cells can pickup and metabolize lactate for energy
21
Q
In aerobic metabolism, where do the 3C pyruvate molecules go?
A
Enter mitochondria and convert to 2C acetyl CoA and then undergo CAC
22
Q
What is released when 3C pyruvate is converted to 2C acetyl CoA?
A
CO2 and 2H+ (picked up by NAD+)
23
Q
What is needed for pyruvate to be converted to acetyl coA?
A
TPP (B vitamin Thiamin), CoA, NAD+
24
Q
Why are B vitamins important for Acetyl CoA?
A
if diet does not contain adequate water soluble b vitamins cells are unable to make coenzymes needed to make acetyl CoA from Pyruvate
25
What is a coenzyme?
allows molecules to attach to enzymes
26
What are the most important products of chemical transformation during citric acid cycle (acetyl coA to Co2)?
the coenzymes NADH and FADH2 are the most important products
27
What does Acetyl CoA covert to by the end of citric acid cycle?
CO2
28
What does 2 C acetyl CoA bind to after entering citric acid cycle?
4C Oxaloacetate (forming 6C citrate)
29
What are the 2 energy shuttles in energy metabolism?
NAD+ and FAD
30
What is a component of both energy shuttles NAD+ and FAD?
B vitamins
31
What b vitamin is a component of NAD+?
niacin
32
What is the B vitamin in FAD?
riboflavin
33
What do coenzymes NAD+ and FAD which are energy shuttles transport?
e- (electrons are transported as energy) and H+ (for positive charge)
34
NADH vs NAD+?
NAD+ is empty
NADH is actively carrying electrons and hydrogen
35
FADH2 vs FAD
FAD is empty
FADH2 is carrying hydrogen and electrons
36
Where do coenzymes FADH2 and NADH carry H+ and high energy e-?
from CAC (in mitochondria) to ETC (inner membrane of mitochondria)
37
What occurs in ETC at the inner membrane of mitochondria?
e- pass through iron containing cytochromes which bind O (thus aerobic) with the H2 making metabolic water, energy released during electron transfer is used to attach P to ADP turning it to ATP
38
Do fructose and galactose (other monosaccharides) go through a similar process as glycolysis for glucose?
- Fructolsyis occurs only in cells in the liver, fructosre is broken down into glyceraldehyde which is converted to glycerol (triglyceride backbone)
- Galactose (converted in a two-step process into glucose, many in liver) catabolized through glycolytic pathway
39
What is Glycogenolysis?
process which breaks down glycogen into glucose
40
What coenzyme is needed for glycogenolysis (glycogen breakdown into glucose)
Pyridoxal phosphate (PLP)
41
What are the primary sites for glycogen storage?
muscles and liver
42
In glycogen breakdown in the muscle, can glucose be released from the muscle?
NO, can only be used by muscles
43
What is gluconeogenesis?
synthesis of glucose from non-carbohydrate precursors: glycerol, lactate, pyruvate and many amino acids
44
What are the three macronutrients which energy can be obtained from?
protein, fats and carbohydrates
45
What is the most energy dense macronutrient group?
triglycerides (fat), they store more energy than glycogen (as seen in atwater value of fat)
46
What facilitates lipolysis (removal of fatty acids from glycerol backbone) of tryglyceride?
HSL (hormone sensitive lipase)
47
Glycerol backbone of triglyceride can be ___ from blood by liver and converted to _____
Glycerol (sugar alcohol) backbone of triglyceride can be REMOVED from blood by liver and converted to PYRUVATE OR GLUCOSE (through gluconeogenesis)
48
How and where are fatty acids prepared for catabolism?
by binding to CoA in cytoplasm (requires 2 ATP)
49
Where do fatty acids, bonded to CoA in cytoplasm, go from there?
pass through outer and inner mitochondrial membranes with help of carnitine
50
What happens to fatty acids (bonded with CoA) in the mitochondria?
beta-oxidation
51
What happens to fatty acids in beta-oxidation?
fatty acids are broken down into numerous 2C acetyl CoA which undergo CAC and ETP (lot of atp is made since so many acetyl CoA are made)
52
How are fatty acids turned into acetyl CoA by beta-oxidation in the mitochondria?
enzymes break off 2 carbon segment from the fatty acid (the hydrogens are picked up by FAD and NAD+), repeated until only a 2-carbon segment (acetyl-CoA remains)
53
What is required for acetyl CoA to enter CAC and then ETP
O2 and oxaloacetate
54
In fat metabolism, What do the NADH and FADH2 from beta-oxidation and CAC do?
shuttle e- to ETC
55
Does the catabolism of fatty acids provide a lot of ATP?
YES, a lot of ATP is made from the breakdown of fatty acids (bonded to CoA) which undergo beta-oxidation (removal of 2C acetyl-CoA) in mitochondria and then the many acetyl CoA undergo CAC and ETP.
56
What happen to the acetyl CoAs formed by catabolism of fatty acid in mitochondria if no oxaloacetate (molecule derived from CHO) is present?
Body forms ketone bodies (acetoacetate, beta hydroxybutyric, acetone)
57
What can ketones do?
Used for energy, excretion in urine, accumulate in blood
58
How are ketones used for energy?
Broken down through ketogenesis, can be used as energy (heart, muscle, kidney, can be used for half of brains needs of energy, while other half still needs glucose, which it prefers)
59
What is ketogenesis a response to?
to prolonged fasting or a diet low in CHO (no oxaloacetate to bind to acetyl CoA and undergo CAC and ETC so body forms ketone bodies)
60
What is a ketogenic diet?
High fat, moderate protein, very low carbohydrate
61
When is a ketogenic diet used?
obesity, metabolic syndrome, type 2 diabetes,epilepsy, alzheimer’s and cancer
62
High ketones, increase or decrease hunger?
Decrease, also decreases insulin, which increases lipolysis (loss of fat)
63
What are side effects of ketogenic diet?
headache, nausea, nutritional deficiency, bone mineral loss, low fiber (low carb)
64
Ketogenesis increases lipolysis, where are ketone bodies formed?
liver
65
What 2 out of the 3 ketone bodies can be used as a source of acetyl CoA (and therefore energy)
Acetoacetic Acid
Beta hydroxybutyric acid
66
What ketone body can not be used as source of acetyl coA (and therefore energy) and instead is breathed out and gives one “sweet breath”
Acetone
67
What is the side effect of increased lipolysis by ketogenesis?
release of inflammatory cytokines, can cause inflammatory disorders such as atherosclerosis and cancer
68
Ketones, by accumulating in blood, can…
increase acidity (lowers pH) of blood (ketoacidosis)
69
What is Ketoacidosis?
increased ketone bodies in blood (acidic), causes body to remove H+ by excretion in urine, causing loss of Na+, K+, Cl-, H20
70
Ketoacidosis can lead to..
nausea, vomitting and coma/death due to low pH of blood
71
How can you tell early sign of ketosis?
Fruity breath (due to acetone ketone body being breathed off)
72
In a resting muscle, what does the excess of ATP (due to low demand and high supply) do?
- some of the mitochondrial atp is used in conversion of glucose to glycogen
- mitochondrial atp is also used to convert creatine to creatine phosphate
Glycogen and CP are both ENERGY RESERVES in the muscle
73
In moderate activity, what happens in the muscle to generate energy (with increased demand for ATP but still enough oxygen for mitochondria)?
- muscle fibre relies on aerobic metabolism of glucose from stored glycogen to make ATP
- if glycogen reserves low, muscle fiber can breaks down fatty acids
- all of atp is used for muscle contraction
74
During peak activity, what happens in the muscle to generate energy (with extremely high demand for ATP and oxygen unable to diffuse into fiber fast enough to meet demand of mitochondria)?
- only some ATP comes from aerobic metabolism (1/3 of need)
- rest of ATP comes from glycolysis outside mitochondria (anaerobic-no oxygen needed)
- pyruvate from glycolysis is converted to lactic acid and then lactate
75
Under normal conditions how do cells use amino acids?
to synthesize essential proteins (enzymes, hormones, structural proteins)
76
When requirement must be filled for cells to catabolize amino acids into other molecules or ATP (glucose, fatty acids)?
after synthesis of essential proteins is complete
77
What are the primary energy stores for the body?
Glucose and fat
78
If there isn’t enough glucose, ___ of protein will break down protein to produce glucose
gluconeogenesis
79
What key processes cannot be performed due to gluconeogenesis of proteins (because of low glucose)
- growth and maintenance of cells
- transport
- production of enzymes and hormones
- immune system regulation
80
Why are carbohydrates so important in protein metabolism?
low cho can cause proteins to be used for energy resulting in protein to be unable to perform its own tasks (transport, growth of cells, production of enzymes and hormones)
81
What does Deamination (removal of amino group which is converted to ammonia and excreted in urine) produce?
- Can produce 3C molecules (pyruvate) that can be used to synthesize glucose
- can produce 2C molecules that form acetyl CoA, enter CAC, etc. for ATP production
82
Both deamination and transamination require…
PLP (from vitamin B6)
83
In protein metabolism, What happens to cells when they don’t have enough Vitamin B6?
they can not produce enough PLP for transamination and deamination
84
What do you call amino acids that are broken down into pyruvate or other intermediates of CAC?
Glucogenic Amino Acids
85
What do you call amino acids that enter catabolic energy pathways as acetyl CoA?
ketogenic amino acids (can be converted to ketone bodies when glucose availability is low)
86
Can some amino acids be glucogenic AND ketogenic?
Yes some AA are both glucogenic (broken down to pyruvate or other intermediates of CAC) and ketogenic (broken down to acetyl CoA)
87
True or false?: the amount of atp formed by catabolism of carbon skeleton depends on where it enters pathways
Yes
88
3 Steps of Protein Metabolism
1. N containing side group of amino acid is removed by deamination or transamination
2. Carbon skeleton forms
3. carbon skeleton can be converted into pyruvate, acetyl CoA or intermediate of CAC to undergo CAC for ATP
89
What is the simplest and least costly macronutrient to convert to triglycerides (main storage form of energy in body) for storage needs?
fatty acids are easier to convert to triglycerides then glucose or amino acids are to convert to triglycerides for storage
90
What happens to extra sources of energy instead of being catabolized?
stored
91
Do people have different energy storage values based on body size and fitness?
Yes storage values can differ greatly based on size and fitness of a person
92
What happens to excess glucose if cells needs are met?
glucose is stored as glycogen in the liver or muscle glycogen stores
93
How is glucose converted to glycogen by liver?
excess glucose is converted to glycogen through enzymatic actions of glycogen synthase
94
How is glucose converted to glycogen in muscles?
pancreas releases insulin in response to glucose in the blood, allows cells to take up the glucose inside the muscle cells
95
What has more storage space for glycogen, the liver or all of the skeletal muscles?
skeletal muscles
96
About how much glycogen can be stored in the body (g)?
415-425 (can vary a lot based on size and fitness)
97
What happens to glucose when cells energy needs are met and glycogen stores are full?
excess glucose stored as fat (in adipose tissue, adipocytes)
98
What is the process by which acetyl CoA (derived from cho from glycolytic pathway - glucose to pyruvate to acetyl CoA) produces fatty acids?
Lipogenesis
99
What is lipogenesis?
production of fatty acids from acetyl CoA (derived from CHO from glycolytic pathway)
100
When triglycerides are stored as fat, what happens in liver?
- absorption of triglycerides leads to lot fat in liver
- most of this fat is incorporated into VLDLs, while some remains in liver
- liver released VLDL into blood
101
When VLDL are in the blood, how do triglycerides from VLDL get into cells?
lipoprotein lipase breaks triglycerides into fatty acids and glycerol so they can enter cells, then triglyceride reformed inside cell (requires very little energy)
102
How does eating CHO affect fatty acid catabolism?
When CHO consumed, glucose is catabolized to make ATP, stopping the breakdown of fatty acids for ATP, results in synthesis and storage of triglycerides in adipocytes
103
Process of lipogenesis and fatty acid conversion explain why high CHO consumption can lead to…
accumulation of body fat
lipogenesis: when energy needs met and glycogen stores full, lipogenesis converts 2C acetyl CoA (derived from CHO) to fatty acids
fatty acid conversion: breakdown of triglyceride outside cell and reformation inside cell requires little energy and is primary route for storing excess fatty acids and CHO (2C acetyl CoA)
104
Why can’t ketogenic amino acids be used to make glucose?
ketogenic amino acids are turned into 2C acetyl coA, the pathway of pyruvate to acetyl coA is irreversible, 2C acetyl CoA can not be converted to 3C pyruvate and therefore can not be converted to 6C glucose
105
Name 3 ways Energy is used in the body
Metabolism
Ion transport
Cellular maintenance/repair
Physiological Functions (breathing)
Physical Activity (small portion)
106
When there is a surplus of food, fate of energy (whether it is stored/burned) is determined by..
Hormones
107
What role do hormones play in metabolism?
key hormones direct / regulate metabolic activities
108
Where is Thyroid Hormone produced?
Thyroid Gland (base of throat)
109
What is the general function of the thyroid hormone?
Increases or Decreases rate of metabolism
110
How does Thyroid increase and decrease rate of metabolism?
Increases rate of glucose catabolism, lipolysis and protein synthesis
111
Thyroid levels decrease when....
Food is not available (starvation, fasting)
112
Thyroid levels increase during...
growth and development
113
What is the general function of insulin?
promotes energy storage and inhibits energy use
114
What is insulin's role in metabolism?
Directs liver and muscle to slow glycogenolysis (breakdown of glycogen) and increase glycogenesis (glucose stores as glycogen)
115
Insulin increases...
fatty acid uptake and triglyceride synthesis by adipocytes
116
Does insulin play a role in protein metabolism?
Yes, stimulates protein synthesis in cells
117
Is insulin a anabolic or catablic hormone?
Anabolic (making of larger molecules), happens when fed
118
Is thyroid catabolic (fasted) or anabolic (fed) hormone?
Both
119
What are the 3 catabolic (fasted) hormones?
Glucagon, cortisol, epinephrine
120
When are catabolic hormones released?
Fasting, low blood sugar, stress, exercise, SNS (fight or flight)
121
What is the general function of catabolic hormones?
Increase availability of energy from storage
122
What happens in body in response to overnight fast?
Glucagon tells liver to increase glycogenolysis (breakdown of glycogen into glucose) and increase gluconeogenesis (convert glucogenic AA into pyruvate and then glucose)
123
While glucagon is signalling to increase glycogenolysis and gluconeogenesis, what does. the body use as main source of fuel?
fatty acids
124
What switches body from state of catabolism (fasting) to anabolism when you break the fast?
Insulin
125
During starvation, when liver glycogen stores are depleted, what occurs in body?
- Muscle cells rely more on fatty acids for energy
- body finds alternative sources of glucose (gluconeogenesis and ketogenesis)
- muscle cells breakdown to release amino acids (proteolysis) which liver can use if glucogenic for gluconeogenesis
126
The energy balance is simply Input vs output: true or false?
FALSE, much more at play
127
What is the energy currency of the cells?
ATP
