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MBM > Energy Production and Utilization > Flashcards

Energy Production and Utilization Flashcards

1
Q

What is bioenergetics? (4)

A

the process by which we utilize fuels that we consume to form energy that our body can use for processes throughout the body

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2
Q

what is catabolism? (4)

A
  • generates energy
  • exergonic
  • break down carbs, proteins, fats into usable products
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3
Q

what is anabolism? (4)

A
  • requires energy
  • endergonic
  • reform complex molecules such as proteins
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4
Q

What is the link between anabolic and catabolic processes? (4)

A
  • we use energy released from a catabolic reaction to power an anabolic reaction (coupled reaction)
  • energy is transferred in the form as ATP
  • hydrolysis of ATP with water, a high energy bond is ruptured releasing energy, and producing adenosine diphosphate (ADP) and inorganic phosphate (slide 11)
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5
Q

What are types of work requiring body energy?

A
  • mechanical (muscle work-needs ATP)
  • anabolic (biosynthesis-DNA, RNA, protein)
  • active transport (delivery of nutrients and building blocks-K+/Na+ pump)
  • heat production (shivering when cold)
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6
Q

what are the thin and thick filaments in muscle?

A

thin- actin

thick-myosin

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7
Q

How does actin and myosin interact to generate a muscle contraction? (6)

A
  • myosin head has an actin binding site and ATP binding site
  • to attach to actin, myosin head hydrolyzes ATP to ADP + Pi causing a myosin conformational change
  • energy release causes thick and thin filaments to slide/contract
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8
Q

What element is essential for ATP production and utilization in muscle? What does a deficiency cause?

A

magnesium

-deficiency impairs virtually all metabolism by disrupting ATP production and utilization

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9
Q

What is the bodys currency to perform work?

A

ATP

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10
Q

What is the structure of ATP? (8)

A

-nitrogenous base, ribose sugar, 3 phosphate groups attacked by ester linkage (alpha, beta, gamma)

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11
Q

What releases energy in ATP? (8)

A
  • when high energy phosphates bonds are broken
  • gamma phosphate = -7.3kcal energy released (distal)
  • beta phosphate= -6.6 kcal energy released (middle)
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12
Q

What is the AMP ratio?

A

ATP/ADP ratio

-body monitors this ratio to make sure there is enough ATP to carry our processes

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13
Q

What are other molecules with high energy bonds? importance? how is the work fueled? (9)

A
  • 1,3 bisphosphoglycerate (intermediate in glycolysis)
  • phosphoenolpyruvate (intermediate in glycolysis)
  • acetyl CoA (high energy thioester bond, citric acid cycle)
  • creatine phosphate (nervous tissue and muscle)
  • these molecules can be interconverted to ATP (PO4 group converts ADP to ATP)
  • they also participate directly in energy requiring reactions
  • work is fueled by biological energy conversion:
    1. body’s energy needs are coupled to synthesize ATP
    2. synthesis of ATP is coupled to fuel metabolism
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14
Q

Stages of fuel oxidation? (10)

A
  1. Fuel goes in the body in the form of food (carbs, proteins, fats)
  2. food is broken down (oxidized) and waste (CO2) is released
  3. coenzymes act as carrier molecules to carry energy
  4. coenzymes are oxidized and reaction starts over
  5. ATP is produced
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15
Q

Describe the coupling of energy release to other biological processes? (slide 14-truck)

A
  1. we consume food
  2. food is oxidized into CO2, ammonia, water (catabolism), exergonic
  3. hydrogen ions are carried in oxidized form on carrier molecules
  4. carrier molecules are now in reduced form (NADH)
  5. transfer energy to another location
  6. anabolism to make ATP
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16
Q

Why is the synthesis of ATP essential for life?

A
  • energy in food is converted to ATP
  • each day we makes, breaks down and remakes an amount of ATP is the mitochondria that is about the same as our body weight
  • energy in ATP powers all biological processes
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17
Q

What is the mitochondria used for?

A
  • oxidative phosphorylation
  • electrochemical gradient
  • electron transport chain
  • ATP synthase
  • reducing equivalents
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18
Q

Oxidative phosphorylation in mitochondria?

A
  1. outer mitochondrial membrane is permeable to anions and small molecules
  2. inner mitochondrial membrane is impermeable to almost everything, including protons
  3. protein complexes of electron transport chain and ATP synthesis are embedded in the inner mitochondrial membrane
  4. electron transport chain accepts electrons from NADH in the mitochondrial matrix or form flavin containing proteins (flavoproteins) embedded in the membrane
  5. ATP synthase projects into the matrix, where it generates ATP
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19
Q

ATP synthesis involves the inter conversion of energy from what in the mitochondria (slide 16)?

A
  1. oxidation/reduction (chemical energy) to
  2. an electro chemical gradient (potential energy) which drives phosphorylation of ADP forming the biologically necessary energy currency of a high energy phosphate bond on ATP
  3. mechanical movement of the ATP synthase (kinetic energy) to synthesize ATP
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20
Q

Efficiency of fuel oxidation? (combustion vs oxidation, slide 17)

A

Oxidation:

  • 68% goes to ATP production through glycolysis, Krebs, electron transport
  • 32% goes to heat production
  • maintains body temp
  • pulls reaction forward
  • small activation energies
  • energy is stored
  • more efficient combustion:
  • large activation energy overcome by heat from fire
  • all free energy is released as heat, none stored
  • less efficient
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21
Q

Example of useful work? (slide 18)

A

-coupled reaction creates useful work

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22
Q

Endergonic and exergonic reactions are ______.

A

coupled

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23
Q

How can we quantitatively describe metabolic reactions?

A

delta G -Gibbs free energy

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24
Q

The energy of a chemical reaction predicts what?

A
  • predicts the net direction of the reaction and how changes in energy are related to achieving chemical equilibrium
  • by quantifying the free energy of reactants and products we can estimate the direction and nature of a chemical reaction
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25
Q

What is Gibbs free energy? delta Go (not)? what can it be used to predict?

A
  • delta G
  • change in free energy
  • it is the energy available to do useful work in a biological setting where temp, pH, and concentrations vary
  • delta Go- the standard free energy change, is measured i the lab at pH 7, with all reactants and products at 1M
  • the change in free energy can be used to predict the direction in which the reaction will proceed
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26
Q

Negative delta G reaction? positive delta G? delta G=0? (slide 22)

A

negative- spontaneous, favored reaction, net loss of energy, exergonic Gsub > Gprod = -G

positive- non spontaneous, disfavored reaction, net gain of energy, endergonic Gsub < Gprod = +G

G=0 - equilibrium, reversible

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27
Q

At equilibrium, the free energy change depends on what?

A

the concentrations of substrates and products

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28
Q

What is the equilibrium constant?

A

Keq = [C][D]/[A][B] or products/reactants

aA + bB -> cC + dD

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29
Q

If Keq > 1, what is delta G? If Keq < 1, what is delta G?

A

Keq > 1, delta G is negative, more products formed, exergonic

Keq < 1, delta G is positive, not much products formed, endergonic

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30
Q

What does a larger and more negative delta G indicate?

A

less substrate relative to product is required to produce a negative delta G

-the more likely the reaction is to proceed spontaneously

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31
Q

Coupling of favorable and unfavorable processes (slide 24) example?

A

a. exergonic (negative)
b. endergonic (positive)
c. total

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32
Q

Describe this table (slide 25)?

A
  • above ATP are high energy compounds
  • below ATP are low energy compounds
  • each compound in the table will accept a Pi from those above it, or donate a Pi to those below it
  • thus, ADP can receive a Pi from PEP to produce substrate level phosphorylation wishing glycolysis, and ATP, the product, can donate a phosphate to Glucose or Glycerol
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33
Q

What does the speed of a reaction depend on?

A
  • depends on the properties of the enzyme that catalyzes a reaction
  • remember: delta G describes the energy inherent in each chemical reaction
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34
Q

What does an enzyme not affect?

A

does not affect Keq (relative concentrations of substrates and products at equilibrium)

-thus, enzyme hexokinase simply facilitates the transfer of a phosphate from ATP to Glucose

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35
Q

For a sequence of reactions that have common intermediates, the standard free energy changes are _____. Example? (slide 27)

A

additive example: hexokinase brings the two substrates in close proximity and couples their reactions

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36
Q

What are rules to remember for anabolic (synthesis) and catabolic (degradation) pathways?

A
  1. synthetic and degradative pathways usually use the same enzyme for steps in which delta G=0
  2. synthetic and degradative pathways always utilize different enzymes for steps in which delta G<0
  3. regulatory steps (G < 0) are often the same in both pathways
  4. regulatory enzymes are always different and they can respond to regulatory signals in different ways
  5. flux through pathways is often controlled by competing rates of synthesis and degradation
37
Q

In metabolism, fuels are used to produce what?

A
  1. reducing equivalents (coenzymes, carriers)
  2. ATP (substrate phosphorylation in RBCs)
38
Q

What are fuels that are body uses? where do we get these fuels?

A
  1. carbs (CHO)
  2. fats (FA)
  3. amino acids (AA)
    - all produce ATP
    - all generate reducing equivalents
    - we get these fuels from food or mobilization of body stores
39
Q

What happens to fuels when they enter the body?

A
  • they come in highly reduced and are oxidized during metabolism
  • O2 is reduced to H2O

Glucose-> glycolysis -> acetyl CoA -> TCA -> CO2 Fatty acids -> beta oxidation -> acetyl CoA -> TCA -> CO2 Amino acids -> TCA cycle -> CO2

40
Q

what are the energy yields of certain fuel sources (slide 32)?

A

Fat- 9 kcal

CHO- 4 kcal

Protein- 4 kcal

alcohol - 7 kcal

41
Q

Where is each form of energy stored? what form are they mobilized in? (slide 34)

A
  1. Fat - adipose tissue, mobilized as ketone bodies
  2. Proteins - in muscle, mobilized as amino acids
  3. Glycogen- in muscle and liver, mobilized as glucose
42
Q

1 mole of glucose converts to how much energy?

A
  • yields 34-36 ATP
  • largest part of our dietary calories
43
Q

1 mole of palmitate (fats) yields how much energy?

A
  • yields 129 ATP
  • most efficient fuel
44
Q

What form is fat stored in? what makes it efficient?

A
  • stored as triglycerides
  • main energy source
  • most efficient because stored without water
45
Q

What form is carbs stored in the body?

A
  • stored as glycogen
  • supply largest part of dietary calories
  • cannot exist in the body without water
46
Q

What form is protein stored in the body?

A
  • no specific storage protein
  • all proteins have a specific function
  • usually stored with water
47
Q

Intersection of metabolic pathways, how it all fits together?

A
  • large complex molecules
  • broken down to simple molecules
  • glycolysis
  • TCA cycle
  • reduced coenzymes
  • oxidative phosphorylation
  • end products
48
Q

What is energy expenditure a sum of?

A

sum of internal heat produced and external work

  • internal heat- sum or REE, the thermic effect of food (DI), and temp induced
  • external work- physical activity
49
Q

What is total energy expenditure (TEE)?

A

BMR + PA

  • BMR- basal metabolic rate (REE + AT)
  • PA- physical activity
50
Q

What is basal metabolic rate? how is it calculated?

A

-the total heat energy released from the body at rest, 8-12 hours post absorptive state after last meal

REE + AT

  • REE- resting energy expenditure (post absorptive state, 50-70% respiration)
  • AT- adaptive thermogenesis (diet induced and temperature induced)
51
Q

How is TEE measured?

A
  1. direct calorimetry- total heat liberated measured over time
  2. indirect calorimetry- rate of O2 consumption or respiratory exchange rate (RER)

RER = V CO2/ V O2

52
Q

How are calories for BMR calculated?

A

weight (kg) * 24 kcal/kg/day

53
Q

What factors affect BMR?

A
  • sex
  • age- decreases with age (people don’t maintain lean body mass) and with the loss of lean body mass
  • body weight
54
Q

Lifestyle calorie expenditure, additional energy demands of BMR? (slide 39)

A

sedentary - 30% more

moderate - 40% more

heavy - 50% more

BMR = weight(kg) * 24 + percentage above

55
Q

What is adaptive thermogenesis? what is regulated by? two types?

A
  • body’s generation of heat, can be measured to determine the amount of energy expended
  • regulated by brain
  • part of sympathetic nervous system’s attempt to maintain homeostasis during environmental changes
  • typically is response to excessive caloric intake or cold exposure
  • two types:
    1. diet induced
    2. temperature induced
56
Q

What is diet induced thermogenesis?

A
  • the thermic effect of food or production of heat by the body, which increases 30% above the resting level during digestion and absorption of food
  • proposed to represent the body’s attempt to maintain a fat mass set point
  • this process contributes to the ability of some individuals to resist weight gain while others readily become obese
57
Q

What is temperature induced thermogenesis?

A
  • responsive to temperature (cold exposure), localized in adipose, skeletal muscle, and heart
  • the generation of heat, particularly in brown adipose tissue, provides necessary warmth
  • may aid the body to burn excess food and avoid weight gain (UCPs)
58
Q

What are uncoupling proteins (UCPs)? (slide 44)

A
  • family of mitochondrial inner membrane found in brown adipose tissue that mediates adaptive thermogenesis
  • UCPs dissipate the proton gradient by permitting leakage of protons from the inter membrane space to the matrix
  • generate heat and burn calories without ATP synthesis -promote fatty acid metabolism in muscle
  • secretion from pancreatic beta cells
  • regulation of insulin
59
Q

What specific UCPs were identified in brown fat of animals?

A
  • UCP 1- as of last week, study showed it plays a role in energy balance in human adults
  • UCP 2- brain, muscle, and adipose
  • UCP 3- skeletal
60
Q

What are artificial uncouplers?

A
  • used to induce weight loss
  • weight loss pills, regimens
  • fatal side effects (dinitrophenol)- generate heat to lose weight, but body temp would spike and person would die
61
Q

uncoupling proteins and brown adipose tissue?

A
  • Brown adipose tissue (BAT) catabolizes lipids to produce heat via UCP-1.
  • BAT differentiation induced by prolonged cold exposure and β-adrenergic stimulation led to increased UCP1 expression

. -Brown fat cells can be derived from inguinal subcutaneous white adipose tissue, a.k.a. beige cells, via browning process.

  • Loss of BAT function linked to obesity and metabolic diseases.
  • Increased BAT associated with lean, healthy phenotype because brown and beige fat increases energy expenditure and insulin sensitivity.
62
Q

What did the Fabbiano study of caloric restriction to promote browning of white fat via type 2 cytokine signaling find out? and do?

A
  • studied two groups of mice, one group could eat freely (AL) and the other group restricted their caloric intake (CR) by 30%
  • exposed them to cold
  • assessed UCP1 expression and cytokine signaling
  • infrared imaging showed CR mice maintained basal body temps better
  • caloric restriction promotes beige (brown adipose tissue differentiation) fat by enhancing type 2 cytokine signaling
63
Q

What energy sources do we use when we need energy in seconds? minutes? hours? months?

A
  • seconds- cells (ATP)
  • minutes- blood glucose
  • hours- meals
  • months- storage
64
Q

What is the driving force behind energy metabolism? regulation?

A

the brain’s requirement for glucose

-fuel utilization is a highly regulated process

65
Q

What is organ specialization and how is it coordinated?

A
  • division of labor, different tissues carry out different pathways and at different rates
  • coordination of metabolism in various organs of mammals is achieved at molecular level by hormones
66
Q

What are the maintainer organs? role?

A
  • liver (master organizer)
  • adipose tissue
  • ensure that consumer organs have the fuels they need
67
Q

Functions of liver?

A
  1. regulates level of glucose by storing as glycogen and releasing and making glucose from precursors (AA, lactate)
  2. regulates blood levels of glucose and ketone bodies in brain
  3. provides ketone bodies when glucose is low
  4. converts glucose to fats for storage when glucose is in excess
  5. initial site of oxidation of unique fuels (ethanol)
  6. detoxifies drugs
  7. dispose of excess fuels from diet (glycogenesis)
  8. provide fuels in between meals
68
Q

Functions of adipose tissue?

A
  1. stores fat from blood as triglyceride
  2. releases fat as free fatty acids
69
Q

What is the most efficient form of storage? why?

A

triglycerides

  • b/c of its lipophilic nature and highly reduced state of fatty acyl chain
  • complete catabolism yields almost twice the free energy as anhydrous glycogen
  • glycogen is highly hydrated, its effective mass is greater, so anhydrous fat yields six times more energy
70
Q

where does adipose tissue obtain most of its fatty acids?

A

from circulating chylomicrons and VLDL

71
Q

What are the consumer organs?

A
  • brain
  • muscle
  • RBCs
  • negative feedback by ATP concentration
72
Q

What fuels does the brain use? cannot use?

A
  • requires a supply of fuel and oxygen from circulation -cannot burn fatty acids
  • uses 20-25% of normal REE
  • glucose and ketone bodies
73
Q

What fuels does the RBCs use?

A

glucose only

74
Q

What fuels do the muscles use?

A
  • uses glucose, ketone bodies, and fatty acids
  • uses 20-80% of total energy metabolism
  • contains significant glycogen storage for its own use
  • major reserve of body proteins
  • spares brain glucose and ketone bodies during exercise
75
Q

Hierarchy of fuels oxidized in consumer organs? (slide 53)

A

see chart

76
Q

Tissue fuel dependency? (slide 54)

A

see chart

77
Q

Skeletal muscle vs cardiac muscle in muscle metabolism?

A
  1. heart muscle cells are rich in mitochondria facilitating aerobic respiration and can function only under aerobic conditions
  2. heart muscle is not able to store glycogen
  3. fatty acids are the preferred fuel of the heart
    - glucose is the least favored fuel
    - ketone bodies and lactate are used under stress when the energy demand is high
78
Q

What are the excretory organs?

A
  • kidneys
  • lungs
79
Q

Functions of kidneys?

A
  1. uses ATP to excrete waste
  2. excretes non-volatile waste, H+ and N (urea, ammonia)
  3. excretes the excess acid formed during energy metabolism
80
Q

Functions of lungs?

A

excretes volatile waste, CO2

81
Q

Role of insulin?

A
  1. transport of glucose into muscle
  2. glycogen synthesis
  3. inhibits glycogen breakdown in liver
  4. triacyglcerols synthesis
  5. inhibits triacylglycerol breakdown
82
Q

Role of glucagon?

A
  1. glycogen breakdown
  2. glucose release from liver
83
Q

describe the fed state? (slide 58)

A

1,2,3. digestion of food (fats are contained in particles of chylomicrons so that they are miscible with blood)

  1. increase in blood glucose causes increase in insulin and decrease in glucagon
  2. liver oxidizes glucose for energy
  3. liver stores glucose as glycogen
  4. liver stores glucose as triacylglycerols
  5. glucose is used as fuel for brain
  6. RBCs breakdown glucose
    - use anaerobic glycolysis, no mitochondria
  7. glucose is taken up by muscle and adipose tissue for energy
  8. glucose taken up by muscle to make glycogen
  9. fatty acids and glycerol generated within chylomicrons, coming from intestines, and VLDL from liver
  10. these fatty acids are used by muscle for energy, and by adipose tissue to make triglycerides for storage
  11. all tissues take up amino acids to make proteins, these amino acids can be oxidized for energy if needed

Main concepts:

  • glucose is main fuel source
  • liver uses glucose and converts excess to glycogen and triacylglycerols (storage)
  • brain uses glucose
  • RBCs use glucose (anaerobic glycolysis)
  • muscle uses glucose and stores glycogen
  • protein turnover in muscle and liver
84
Q

Describe the fasted state (post absorptive state, 12-18 hours)? (slide 59)

A
  1. in the fasted state, blood glucose is low, blood insulin is decreased, and glucagon is increased
  2. under these conditions, liver does not use glucose as fuel, but supplies glucose to the blood by glycogenolysis, and by gluconeogenesis (synthesis of new glucose) from lactate (from RBCs), amino acids (from protein) and glycerol (from adipose tissue)
  3. tissues that use this glucose for fuel are brain and RBC (4)
  4. triglycerides stored in adipose tissue will be hydrolyzed to produce fatty acids for fuel
  5. fatty acids will be used by muscle for fuel, liver also used fatty acids for fuel
  6. liver oxidizes fatty acids to produce ketone bodies
  7. these ketone bodies are used by muscle for fuel
  8. proteolysis occurs in muscle, and the amino acids produced are used for the liver for gluconeogenesis
  9. carbon skeletons of the amino acids are used for gluconeogenesis, the nitrogen used to make urea, a waste product is excreted by the kidney
  10. lactate (produced by RBC and exercising muscle) travels in the blood to the liver where it is converted to glucose by gluconeogenesis
  11. glycerol used in gluconeogenesis to produce glucose

main concepts:

  • liver maintains glucose by glycogenolysis
  • muscle proteolysis
  • adipose lipolysis, fatty acids main fuel source
  • RBC use glucose (lactate-liver-Cori cycle)
  • gluconeogenesis in liver (lactate, glycerol, AAs)
  • brain uses glucose
85
Q

Describe the prolonged fasting state or starved state (more than 4 days)? (slide 60)

A
  1. liver glycogen is depleted by day 2 of a fast, the body must then adjust to a decrease in blood glucose
  2. on day 4, muscle proteolysis decreases to an extremely low level, almost no AAs are available for gluconeogenesis, and blood glucose decreases further
  3. on day 4, muscle stops using ketone bodies for fuel and uses fatty acids exclusively, the concentration of ketone bodies in blood increases significantly and the brain will then use ketones for energy along with glucose (4)
  4. this situation prevails for weeks depending on the original weight of the individual

main concepts:

  • liver glycogenolysis ends
  • liver gluconeogenesis maintained for RBC
  • fatty acids are fuel source in muscle and liver
  • muscle protein sparing
  • brain uses ketone bodies
86
Q

Summary of metabolic changes during prolonged fasting? (slide 61)

A

see chart

87
Q

Metabolic capacities of various tissues? (slide 62)

A

see chart

  • note: liver can do almost everything, but it doesn’t utilize the ketone bodies it forms for the use of brain and muscle
  • muscle can perform most metabolic pathways but it doesn’t form ketones, fatty acids, or glucose
  • brain is limited, but the erythrocyte only performs glycolysis for all of its energy needs
88
Q

Overview of tissue metabolism? (slide 63)

A

see pic

MBM (24 decks)

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