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Biochemistry > Bioenergetics and Regulation of Metabolism > Flashcards

Bioenergetics and Regulation of Metabolism Flashcards

1
Q

Chapter Outline

A 
1. Thermodynamics and bioenergetics
          I. Biological Systems
         II. Enthalpy, entropy, and free energy
        III. Physiological conditions
2. The role of ATP
          I. ATP as an energy carrier
         II. Hydrolysis and coupling
        III. Phosphoryl group transfer
3.  Biologial oxidation and reduction
          I. Half reactions
         II. Electron carriers
                 A. Flavoproteins
4. Metabolic States
           I. Postprandial/absorptive state
          II. Postabsorptive/fasting state
         III. Prolonged fasting/Starvation 
5. Hormonal Regulation of metabolism
           I. Insulin & glucagon
          II. Glucocorticoids
         III. Catecholamines
         IV. Thyroid hormones
6. Tissue specific metabolism
           I. Liver
          II. Adipose tissue
         III. Seletal muscle
         IV. Cardiac muscle
          V. Brain
7. Integrative Metabolism
          I. Analysis of metabolism
         II. Regulation of body mass
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2
Q

Thermodynamics Systems Involved in Biology

A
  1. Open Systems
    I. Systems that involve exchange of
    1. Energy
    I. Mechanical work
    II. Heat
    2. Matter
    I. Food ingestion
    II. Food Elimination
    III. Respiration
    II. Systems involved in organisms as a whole
  2. Closed Systems
    I. Systems that involve exchange of
    1. Energy
    I. Work
    II. Heat

In closed systems, internal energy can be easily measured

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3
Q

Internal Energy

U

A

Sum of all of the interactions b/w and within a cell

examples:
1. rotation
2. linear motion
3. vibration

Formula:

Delta U = Q - W

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4
Q

Work in Thermodynamics

A

work=−PΔV

involve change in pressure and volume

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5
Q

Bioenergetics

A

Concept that describes changes in energy states of biological systems

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6
Q

Gibs Free Energy; Enthalpy; Entropy

A

1: Gibbs free energy: ΔG:
I. measure of spontaneity of a chemical rxn in
a biological system
2. Enthalpy: ΔH:
I. measure of change in heat during a rxn
3. Entropy: ΔS:
I. measure of disorder and energy dispersal
of a rxn

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7
Q

Formula that relates ΔG, ΔH, & ΔS

A

ΔG= ΔH - TΔS

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8
Q

ΔG Under Standard Vs. Nonstandard Conditions

A
  1. Nonstandard: ΔG= ΔH - TΔS
  2. Standard: ΔG= ΔG* + RT* ln (Q)
    * *************
    1. R= universal gas constant
    2. Q=reaction quotient
    3. T= temperature
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9
Q

ATP

A
  1. Name:
    I. Adenosine Triphosphate
  2. Identity:
    I. Energy currency in the body
    II. Provides 30kj/mol of energy
  3. Generating pathways:
    I. Substrate level phosphorylation
    II. Hydrolysis
    III. Oxidative phosphorylation
    IV. Glycolysis [minor]
    V. Citric acid cycle [indirect-from GTP]
  4. Significance
    I. Contains high-Energy p-bond that can be cleaved
    and transferred to
    1. provide energy for
    1. coupled rxns
    2. unfavorable, energy costing rxns
    2. activate or deactivate enzymes

ATP synthesis is a continuous recycling process of ADP and P*

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10
Q

Coupled Rxns

A

2 reactions taking place simultaneously with one reaction providing the energy source for the other reaction

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11
Q

Hydrolysis

A

Break down of a molecular bond using water as a reactant

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12
Q

Half Reactions

A

Separated oxidation or reduction part of a reaction useful for keeping track of electron movements

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13
Q

Electron Carriers

A

I. Identity:
I. Molecules that carry electrons to ETC and that
lose their energy to the proton motive force to
contribute to ATP production through oxidative
phosphorylation
II. Types:
1. Soluble
1. NADH
2. NADPH
3. FADH2
4. cytochrome
5. glutathione
2. inner-Mitochondrial-membrane-bound
1. flavoprotein
I. contain modified Vit B2 or riboflavin
II. Types:
A. FMN [flavin mononucleotide]
I. contains cluster of Fe-S
II. bonds to ETC’s complex I
III. nucleic acid derivative
B. FDN [flavin dinucleotide]
III. Function
1. electron carriers in
1. Mitochondria
2. Chloroplast
2. activators of modified riboflavins
3. coenzymes for enzymes involved in
1. beta-oxidation
2. pyruvate decarboxylation
3. glutathione reduction

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14
Q

Metabolic States

A
  1. Postprandial/Absorptive State
    I. 3-5 hrs following a meal
    II. Rate of anabolism > rate of catabolism
    III. Insulin secretion is high
  2. Postabsorptive
    I. 5-17 hrs after a meal
    II. Release of counterregulatory hormones
    III. Marked by
    1. Glycogenolysis
    2. Hepatic gluconeogenesis
    I. uses
    1. amino acids from muscles
    2. fatty acids from adipose
    tissues
  3. Prolonged fasting [starvation]
    I. Markedly high levels of
    1. glucagon
    2. epinephrine
    II. High levels of
    1. Hepatic gluconeogensis
    A. for cells with few mitochondria
    *ex: red blood cells
    2. Beta-oxidation
    A. for muscle consumption
    3. Ketone synthesis
    A. for brain consumption

**After weeks of starvation, brain cells procure 2/3 of their energy from ketone bodies and 1/3 from glucose produced through gluconeogenesis

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15
Q

Target Tissues for Insulin

A
  1. Liver
  2. Muscles
  3. Adipose Tissue
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16
Q

Processes Following Food Intake

A
  1. Digestion
  2. Nutrient uptake to the liver through the hepatic portal vein
  3. Insulin release
  4. Glycogen synthesis in liver and muscles
  5. Triacylglycerol synthesis in adipose tissues after glycogen stores have been filled
  6. Protein synthesis in muscles
  7. Glucose entry into muscles and adipose tissues
17
Q

Cell Types Insensitive to Insulin

A
  1. Nervous Tissues
    1. Drive energy by oxidizing glucose to CO2
    and H2O
    unless in the starvation state*
  2. Erythrocytes
    1. drive their energy through anaerobic
    glycolysis regardless of metabolic state
  3. Kidney tubules
  4. Intestinal mucosa
  5. Pancreatic Beta-Cells
18
Q

Counterregulatory Hormones

A
  1. Glucagon
  2. Cortisol
  3. Epinephrine
  4. Norepinephrine
  5. Growth hormone

Hormones that oppose action of insulin*

19
Q

Hormonal Regulation of Metabolism

A
  1. Insulin
    I. Peptide hormone
    II. secreted by pancreatic B-cells of langerhans
    III. acts via facilitated diffusion & 2nd messengers
    IV. Affect muscle and adipose tissues
    V. Effect:
    1. increases glucose & amino acid uptake
    2. increases glycogen storage
    3. increases glucose and fat metabolism
  2. Glucagon
    I. Peptide hormone
    II. secreted by pancreatic alpha-cells
    III. act via 2nd messengers
    IV. Target hepatocytes
    V. Effects:
    1. increase the following hepatic pathways:
    1. glycogenolysis
    2. gluconeogenesis
    3. ketogenesis
    4. lipolysis
    2. decrease hepatic lipogenesis
    VI. Regulators:
    1. stimulator:
    A. hypoglycemia
    2. basic amino acids: lysine, arginine
    3. protein-rich meal
    2. inhibitor:
    A. hyperglycemia
  3. Glucocorticoids
    I. Steroid hormones released in response to stress
    II. released from adrenal cortex
    III. Target hepatocytes
    IV. Effects:
    1. Contribute to stress response
    I. release of cortisol
    2. Mobilize fat and protein energy stores;
    breakdown & deliver amino acids and
    lipids to the liver for gluconeogenesis
    3. Inhibit glucose reuptake by
    I. muscles
    II. fat
    III. lymphoid tissues
    4. promote hyperglycemia by promoting
    I. catecholamines
    II. glucagon
    III. epinephrine
  4. Catecholamines
    I. Epinephrine/Adrenaline &
    Norepinephrine/noreadrenaline
    II. Secreted by adrenal medulla
    III. Target
    1. hepatocytes
    I. increase glycogenolysis
    2. skeletal muscle cells
    I. increase glycogenolysis for the
    muscle cell metabolism
    3. adipose tissues
    I. increase lipolysis of adipose tissues
    by increasing activity of hormone-
    sensitive lipase
    4. cardiac tissues
    I. increase basal metabolic rate of
    heart through epinephrine
    release/sympathetic NS regulation
    associated w/ adrenaline rush
  5. Thyroid Hormone
    I. Nucleic Acid-derivative Hormone
    II. Secreted by the thyroid gland & Hypothalamus
    III. Types:
    I. T3
    1. stimulating hormone of T4
    2. quick yet short-living effect
    II. T4
    1. hormone stimulated by T3
    2. latent yet long-lasting effect
    relatively constant levels at all times
    IV. Effects
    I. increase basal metabolic rate of
    1. carbohydrates
    2. lipids
    II. increase glucose absorption rate from
    intestine
    III. clear cholesterol from the plasma
20
Q

Various Categories of Hormones

A
  1. Water Soluble Peptide Hormones
    1. insulin
    2. act quickly via second messenger cascade
  2. Steroid Hormones
    1. cortisol
    2. slow to exert effect b/c of transcriptional
    regulation
  3. Amino-Acid Derivative Hormones
    1. thyroid hormone
    2. slow to exert effect b/c of transcription
    regulation involvement
21
Q

Steroid Hormones

A
  1. glucocorticoids
  2. mineralocorticoids
  3. sex hormones
22
Q

Hormones Released by Adrenal Cortex & Adrenal Medulla

A
  1. Adrenal Cortex:
    I. Steroid hormones
  2. Adrenal Medulla:
    I. Catecholamines
23
Q

Deiodonase

A

Enzyme that converts T4 to T3 by removing an iodone from T4

24
Q

Major Sites of Metabolic Activity in the Body

A
  1. Brain
  2. Cardiac tissue
  3. Skeletal tissue
  4. Adipose Tissue
  5. Liver
25
Q

Liver-Specific Metabolism

A

I. Functions
1. Maintenance of constant blood glucose levels
I. Well-fed state
1. glycogenesis
2. fatty-acid synthesis
i. from excess blood glucose
that is converted to acetyl-
CoA
ii. get released in blood asVLDL
2. Post-absorptive & fasting states
1. glycogenolysis
2. gluconeogenesis
i. contributing reactants:
1. lactate from anaerobic
glycolysis
2. glycerol from
triacylglycerol
3. ketogenic amino-acids
**Following a meal, amino acid metabolism provide hepatic energy*********
2. Ketogenesis during periods of excess beta-
oxidation

26
Q

Adipose Tissue Metabolism

A

I. Well-fed state
1. increased glucose uptake
2. fatty acid uptake from
VLDL/Chylomicrons and its re-
esterification in triacylglycerol storages
2. Fasting State
1. fatty acid release from adipose tissues
into circulation following epinephrine
activation of hormone sensitive lipase

27
Q

Skeletal Muscle Metabolism

A

I. Resting Muscle
1. Well-fed state
1. muscular glucose uptake
2. Muscular amino acid uptake for
protein synthesis
3. Glycogenesis
4. glycolysis and beta-oxidation
2. Fasting State
1. oxidation of circulating free-fatty
acids for energy
3. Prolonged Fasting State
1. oxidation of ketone bodies
II. Active Muscle
1. short-bursts of high intensity exercise
1. oxidation of glycogen stores
A. anaerobic glycolysis
2. beta-oxidation of triacylglycerol store
3. creatine phosphate
2. High-intensity, continuous exercise
1. glycogen stores deplete
2. beta-oxidation continues
rate of exercise declines at rate that
can be supported by beta-oxidation

28
Q

Cardiac Muscle Metabolism

A
  1. Well-fed state
    1. fatty-acid oxidation
  2. Prolonged fasting-state
    1. fatty acid oxidation
    2. ketone body metabolism

In cases of cardiac illnesses like CHF, glucose oxidation increases and B-oxidation falls****
Otherwise, the heart always prefers beta-oxidation***

29
Q

Brain Metabolism

A
  1. Well-fed State
    1. Glucose only
    * Fatty acid does not cross brain’s blood barrier***
  2. Fasting State
    1. glucose from
    1. glycogenolysis
    2. gluconeogenesis
  3. Prolonged-Fasting State
    1. 1/3 glucose
    2. 2/3 ketone bodies

when hypothalamus senses hypoglycemia, it triggers glucagon and epinephrine release**

30
Q

Basal Metabolic Rate or BMR

A

The amount of energy required for one sedentary day

  • measured by calorimetry
  • predicted by
    1. age
    2. gender
    3. weight
    4. height
31
Q

Factors Responsible for Weight Control

A
  1. Diet
  2. Exercise
  3. Socioeconomic Status
  4. Geography
  5. Genetics
32
Q

Hormones that Regulate Hunger and Satiety

A
  1. Ghrelin
    1. secreted by:
    I. stomach
    2. stimulators:
    I. sight
    II. taste
    III. sound
    IV. smell of food
    1. Functions
      I. increase appetite
      II. stimulate orexin release
  2. Orexin
    1. Stimulators:
      I. hypothalamus signal
      II. ghrelin release
    2. Functions
      I. sleep-wake cycle
      II. increases alertness
      III. increases appetite
  3. Leptin
    1. Secreted by:
    I. adipocytes
    1. Functions:
      I. decreases appetite
      II. suppresses orexin production
33
Q

Body Mass Index

A 
1. Formula: 
           Mass/Height^2
2. Range of values
           1. normal 18.5-20
          2. overweight: 20-25
          3. Obese:  >30
34
Q

Respirometry

A

Device that allows accurate measurement of respiratory quotient

35
Q

Respiratory Quotient

A 
Formula: 
            RQ= CO2 produced / O2 consumed
***varies depending on
             1. Type of fuel used
            2. Starvation
            3. Exercise
            4. Stress
Types & levels
             1. RQ of carbs: 1
             2. RQ of lipids: 0.7
             3. RQ in resting individuals: 0.8
                      i. significance: 
                              1. consumption of both carbs & lipids
36
Q

Calorimetry

A

Device that measures BMR

pg 420

Biochemistry (12 decks)

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