“Bioenergetics” Prof. Dr. Metin TULGAR Prof. Dr. Metin TULGAR

Energy Concept In Living Creatures Energy is the ability of an object to do work. Some examples: Transmittion of water from roots to the leaves, Transmittion of water from roots to the leaves, Any movement of an animal, Any movement of an animal, Pump of blood to the vessels. Pump of blood to the vessels. Energy source of livings: Nutrients.

Kinds of Energies for Livings A mechanical work: in muscle contraction, An electrical work: ions, crossing across the membrane, A chemical work: during the synthesis of a substance. If livings can’t transform energy to other forms, they can not survive.

Typical events proving that the cells use energy: Cells keep substances in high concentration. Cells keep substances in high concentration. That the cells move. That the cells move. Ability to synthesize macromolecules from micromolecules. Ability to synthesize macromolecules from micromolecules.

Bioenergetics is; The science that deals with how the energy is produced and transformed in living creatures.

BIOTHERMODYNAMICS Bio(living) +thermo(heat) + dynamics(power): Biothermodynamics is the science that deals with the energy and its transformations in livings.

Here are some concepts of thermodynamics: W: Work that the System does. Q: Energy amount of the System E:Internal Energy of the System Thermodynamics deal with the relationships of these concepts. An example System: Amip (Single-celled organism). Amip consumes energy when it moves. Amip consumes energy when it moves. Heat is transfered between the invironment and Amip. Heat is transfered between the invironment and Amip. Internal energy source of Amip is food. Internal energy source of Amip is food.

Laws of Thermodynamics In order to determine the last situation of this System. Physical charasteristics of a System: Mass, Mass, Volume, Volume, And Temperature. And Temperature.

There are three laws of thermodynamics: 1.Zeroth law of thermodynamics 2.First law of thermodynamics 3. Second law of thermodynamics

Zeroth Law of Thermodynamics The zeroth law of thermodynamics state that: The zeroth law of thermodynamics state that: “If two badies are in thermal equilibrium with a third body, they are also in thermal equilibrium with each body, they are also in thermal equilibrium with each other.” other.”

Figure #1: Three bodies in thermal equilibrium. Consider three bodies A, B, and C with absolute temperatures T A, T B, and T C in thermal equilibrium. Consider three bodies A, B, and C with absolute temperatures T A, T B, and T C in thermal equilibrium. According to the zeroth law of thermodynamics; According to the zeroth law of thermodynamics; if T A = T B, and T A = T C ; then T B = T C. B T B C T C A T A

Also known as conservation of energy principle. Also known as conservation of energy principle. energy change of (heat+work) = internal energy change. energy change of (heat+work) = internal energy change. Internal Energy: Total energy of all the microscobic forms of energy. ( atoms,molecules,ions ) Internal Energy: Total energy of all the microscobic forms of energy. ( atoms,molecules,ions ) First Law of Thermodynamics

Scientific definition of First Law: Scientific definition of First Law: ΔEi = Q + W. ΔEi = Q + W. ΔEi:internal energy change, Q:heat, W:wrok. ΔEi:internal energy change, Q:heat, W:wrok. Internal Energy Function: Ei = u( V, T ). Internal Energy Function: Ei = u( V, T ). V: volume, T: absolute temperature. V: volume, T: absolute temperature. Differentiation of Internal Energy Function: Differentiation of Internal Energy Function: dEi = (  u/  T) V dT+(  u/  V) T dV dEi = (  u/  T) V dT+(  u/  V) T dV

Consider conservation of energy principle; Eu = Ei + Eo Eu = Ei + Eo Eu: energy of the universe, Eu: energy of the universe, Ei: internal energy of system, Ei: internal energy of system, Eo: energy of environment. Eo: energy of environment. If “energy can be neither created nor destroyed”, If “energy can be neither created nor destroyed”, then Eu is constant. Change in internal energy of the system: Ei to Ei’ Change in internal energy of the system: Ei to Ei’ Change in energy of environment: Eo to Eo’ Change in energy of environment: Eo to Eo’ Ei + Eo = Ei’ + Eo’ Ei + Eo = Ei’ + Eo’ Ei – Ei’ = Eo’ – Eo Ei – Ei’ = Eo’ – Eo Then, ΔEi = ΔEo Then, ΔEi = ΔEo

First Law could be concluded as this: First Law could be concluded as this: “Energy can be neither created nor destroyed, it can only change forms”

Ideal Gas Equation of State Ideal gas is an imaginary gas which has Ideal gas is an imaginary gas which has no volume, no volume, no attractive and repulsive forces between its molecules, and no attractive and repulsive forces between its molecules, and no loss of kinetic energy when its molecules collided with each other. no loss of kinetic energy when its molecules collided with each other.

Ideal gas equation of state: P.V = n.R.T Ideal gas equation of state: P.V = n.R.T P: pressure, P: pressure, V: volume, V: volume, n: # of moles, n: # of moles, R: gas constant(8,314j/  Kmol), R: gas constant(8,314j/  Kmol), T: temperature(K) T: temperature(K)

Isochoric Process Process in which volume is kept constant. Process in which volume is kept constant.

“Mathematical analysis of isochoric process” dEi = (  u/  T) V dT + (  u/  V) T dV = dQ + P.dV dEi = (  u/  T) V dT + (  u/  V) T dV = dQ + P.dV For isochoric process dV = 0 For isochoric process dV = 0 => (  u/  T) V dT = dQ = C V.dT C V : specific heat of System in isochoric process C V : specific heat of System in isochoric process For n moles of gases, For n moles of gases, n.  Ei = q V = n.C V.dT n.  Ei = q V = n.C V.dT Thus, for an isochoric process heat energy is absorbed by the system to increase internal energy. Thus, for an isochoric process heat energy is absorbed by the system to increase internal energy.

Isobaric Process process in which pressure is kept constant process in which pressure is kept constant

dE i = dQ - dW dE i = dQ - dW dQ = dE i + dW = dE i + P.dV dQ = dE i + dW = dE i + P.dV Isobaric situations: Isobaric situations: dQ P =dE i + d(P.V) = d(E i + P.V) = dH dQ P =dE i + d(P.V) = d(E i + P.V) = dH => Enthalpy:H = E i + P.V => Enthalpy:H = E i + P.V dQ P = dH dQ P = dH Q P = H These equations result in a conclusion that: These equations result in a conclusion that: “Change in heat energy amount is equal to the enthalpy” Isobaric Process (Continuing)

dH = C P.dT dH = C P.dT C P : specific heat at isobaric process For n moles of gases: For n moles of gases: dH = n.C P.dT Isobaric Process (Continuing)

Enthalpy Consider the Enthalpy with the Ideal Gas Law: H = Ei + P.V = Ei + R.T H = Ei + P.V = Ei + R.T Take the derivative of above equation: dH = dEi + R.dT The resultant equation indicates that: “Internal Energy of ideal gas is only dependent on T”

Consider the other equations together: C P.dT = C V.dT + R.dT C P = C V + R => R = C P – C V Enthalpy (Continuing)

Isothermal Process process in which temperature is held constant process in which temperature is held constant Examples: Ideal gases & ideal paramagnetic crystals Examples: Ideal gases & ideal paramagnetic crystals

For an adiabatic system: For an adiabatic system: ΔQ = 0 ΔE i = ΔQ + ΔW => ΔE i = ΔW If the system is compressed If the system is compressed E i = - W (internal energy ↑, Work is -) E i = - W (internal energy ↑, Work is -) If the system is expanded If the system is expanded - E i = W (internal energy ↓, Work is +) - E i = W (internal energy ↓, Work is +) Adiabatic Process (Continuing)

Adiabatic Process Process in which no heat transfer takes place Process in which no heat transfer takes place Cork, mineral wool, isolated glass must be used to isolate the system Cork, mineral wool, isolated glass must be used to isolate the systemOr; The process should be completed immediately.

Second Law of Thermodynamics

i. states in which direction a process can take place heat does not flow spontaneously from a cold to a hot body heat does not flow spontaneously from a cold to a hot body heat cannot be transformed completely into mechanical work heat cannot be transformed completely into mechanical work it is impossible to construct an operational perpetual motion machine it is impossible to construct an operational perpetual motion machine ii. introduces concept of entropy Second Law of Thermodynamics

“It is impossible for any device that operates “It is impossible for any device that operates on a cycle to receive heat from a single reservoir and produce a net amount of work.” 2 nd Law Statement By Kelvin-Planck To have such a cycle another reservoir with To have such a cycle another reservoir with different temperature is needed. Second Law of Thermodynamics (Continuing)

Reversible and Irreversible Processes Irreversible Process: Irreversible Process: “Once having taken place, these processes can not reverse themselves spontaneously and restore the system to its initial state.” For Example, For Example, Once a cup of hot coffee cools, it will not heat up by retrieving the heat it lost from the surroundings.

Reversible Process: Reversible Process: “A process that can be reversed without leaving any trace on the surroundings.” This is possible only if the net heat and net work exchange between system and surroundings is zero for the combined (original and reverse) process.

Entropy property that indicates the direction of a process property that indicates the direction of a process Entropy, is a measure of disorder is a measure of disorder is a measure of a system’s ability to do useful work is a measure of a system’s ability to do useful work determines direction of time determines direction of time

Entropy (S) equation: Entropy (S) equation: S = Q/T or ΔS = ΔQ / T system Q: heat T: Abs. Temp. Unit Analysis: [Cal]/[˚K] [Cal/mol]/[˚K] (for molar entropy)

For example: For example: An ice (crystalline) molecules are strongly order So, the Entropy is small for ice. Ice →(heat) → Water (liquid) That is, the strong (crystalline) structure is broken. So, the Entropy increases. Water (liquid) →(heat)→ Vapor (gas) Gas molecules are more unordered. That is to say “the Entropy increases more”.

The example can be concluded as this; The example can be concluded as this; “Entropy is increased by the energy given to the system” Relationship bw. the change in Energy & Entropy of System: Relationship bw. the change in Energy & Entropy of System: ΔS > ΔQ/T ΔS > ΔQ/T

Some examples for entropy change If ordered system →an independent system, Entropy ↑. If ordered system →an independent system, Entropy ↑. The reverse cause Entropy ↓. If solids and liquids reacts a gases If solids and liquids reacts a gases Entropy ↑. The reverse cause Entropy ↓. If a Volume ↑, Entropy ↑. If a Volume ↑, Entropy ↑. If a Volume ↓, Entropy ↓.

Standard Absolute Entropy: Change in Entropy, caused by the increase in temperature of pure crystals, in isobaric conditions, from 0K to 298K.

Entropy of Reaction: Change in Entropy of system in isobaric and isothermal conditions, for chemical reactions in which maximum of reaction parameter is 1 mole.

Entropy is dependent of three parameters: Entropy is dependent of three parameters: Temperature Temperature Pressure Pressure Reaction variable Reaction variable S = f(T,P,ξ) S = f(T,P,ξ) T: absolute temperature, T: absolute temperature, P: pressure, P: pressure, ξ: reaction variable. ξ: reaction variable.

Free Energy (also known as Gibbs’ Energy or useful energy) (also known as Gibbs’ Energy or useful energy) In biological systems Free Energy concept is the best method for explaining the energy conversions. In biological systems Free Energy concept is the best method for explaining the energy conversions. Explains the usable component of system’s total energy under isobaric and isothermic conditions. Explains the usable component of system’s total energy under isobaric and isothermic conditions.

The Concept of Free Energy Combine the 1 st and 2 nd laws of thermodynamics: ΔE i = ΔQ – P. ΔV, “ ΔQ = T. ΔS” => ΔE i = T.ΔS – P. ΔV => ΔE i = T.ΔS – P. ΔV ΔE i + P. ΔV – T. ΔS = ΔG, “ ΔE i + P. ΔV = ΔH ” => ΔH – T. ΔS = ΔG => ΔH – T. ΔS = ΔG H: enthalpy H: enthalpy ΔH: change in enthalpy ΔH: change in enthalpy

For the reaction entropy conditions; P & T are constants. P & T are constants. Then: G = Ei + P.V – T.S By this formula the free energy can be calculated.

In a reaction, the change in free energy In a reaction, the change in free energy can be zero, positive or negative value. The sign of free energy change determines the direction of reaction. The sign of free energy change determines the direction of reaction.

The condition that free energy change is; Zero (ΔG = 0), indicates the equilibrium state. Zero (ΔG = 0), indicates the equilibrium state. Negative (ΔG < 0), explains that the reaction Negative (ΔG < 0), explains that the reaction has occurred by giving energy to the environment. Positive (ΔG > 0), indicates the system has taken Positive (ΔG > 0), indicates the system has taken energy from the environment during the reaction.

Radiation Energy (photons) wate r oxyge n carbon dioxide Chemical energy of carbohydrates and other products of cells Thermal and other energies Chemical energy Biological energy Biological Energy Flow 4H→He + 2e + enerji 4H→He + 2e + enerji

Three main steps of Biologic Energy Flow: I.Solar energy → Organic Materials (by ototrof organisms) (by ototrof organisms) II.Organic Materials → ATP (energy) (by respiration) (by respiration) III.ATP → other forms of energy (by biological processes) (by biological processes)

Photosynthesis & Respiration Photosynthesis: Conversion of solar energy (photons) into chemical energy with chlorophyll by the green plants. Photosynthesis: Conversion of solar energy (photons) into chemical energy with chlorophyll by the green plants. (Chlorophyll) (Chlorophyll) 6CO 2 + 6H 2 O + n.h.f.  C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O + n.h.f.  C 6 H 12 O 6 + 6O 2 n: Planck constant (6, j.s) n: Planck constant (6, j.s) h: photon frequency h: photon frequency f: number of photons in the reaction f: number of photons in the reaction

During photosynthesis; Free energy change:  G s = 2867 kj/mol Free energy change:  G s = 2867 kj/mol “glucose formation needs energy” “2867 kJ solar energy is used for each glucose mole” Enthalpy change:  H s = 2810 kj/mol Enthalpy change:  H s = 2810 kj/mol Entropy change:  S s = j/(mol)K Entropy change:  S s = j/(mol)K “reaction is endothermic”

The inverse mechanism of photosynthesis is called respiration. The inverse mechanism of photosynthesis is called respiration. C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O (Glucose)

During respiration; Free energy change:  G s = kj/mol Free energy change:  G s = kj/mol Enthalpy change:  H s = kj/mol Enthalpy change:  H s = kj/mol Entropy change:  S s = 182 j/(mol)K Entropy change:  S s = 182 j/(mol)K “reaction is exothermic”

In heterotrophic organisms the energy of the nutrients’ itself is gained again as a result of cellular respiration (oxidation). In heterotrophic organisms the energy of the nutrients’ itself is gained again as a result of cellular respiration (oxidation). And, this energy is used for the synthesis of ATP molecule. And, this energy is used for the synthesis of ATP molecule. ADP + P İ  ATP + H 2 O ADP + P İ  ATP + H 2 O (Inorganic phosphate) ΔG = kj/mol ΔG = kj/mol

Only some part of the energy obtained from oxidation is used for ATP synthesis; Only some part of the energy obtained from oxidation is used for ATP synthesis; the other part is given to the environment of cell as heat energy. the other part is given to the environment of cell as heat energy. Energy released, while the conversion of ATP to ADP and inorganic phosphate in the cell, is used for the cell’s vital functions. Energy released, while the conversion of ATP to ADP and inorganic phosphate in the cell, is used for the cell’s vital functions. ATP + H 2 O  ADP + P İ ATP + H 2 O  ADP + P İ ΔG = kj/mol ΔG = kj/mol

What could a cell do with hydrolysis of ATP? Biosynthesis: Formation of bigger molecules from smaller molecules. Biosynthesis: Formation of bigger molecules from smaller molecules. Active Transport: Transport of molecules against the concentration gradient of cell membrane. Active Transport: Transport of molecules against the concentration gradient of cell membrane. Mechanical Work: Contraction of muscle cells. Mechanical Work: Contraction of muscle cells.

Energy Distribution In Biomolecular Systems Typical Heat Engine Typical Heat Engine Needs high Temperature differences to work. Needs high Temperature differences to work. Energy transformations done toward the balance. Energy transformations done toward the balance. So, it works with decreasing Entropy. However, Livings Energy transformations However, Livings Energy transformations held on with constant temperature held on with constant temperature Direction of energy transformation is away from balance Direction of energy transformation is away from balance So, increasing Entropy is needed.

Adenosine-tri-phosphate(ATP) is the Energy storage molecule. Adenosine-tri-phosphate(ATP) is the Energy storage molecule. It is made by breaking down nutrients in mitochondriae, It is made by breaking down nutrients in mitochondriae, By the oxidation of 1 mol glucose 18 mol ATP is produced. By the oxidation of 1 mol glucose 18 mol ATP is produced. Adenosine-tri-phosphate is hydrolized with enzymes to form Adenosine-tri-phosphate is hydrolized with enzymes to form Adenosine-di-phosphate (ADP) →Adenosine-mono- phosphate (AMP). Adenosine-di-phosphate (ADP) →Adenosine-mono- phosphate (AMP). The energy coming out is consumed in needed places inside cell.

Enzymes Enzymes have great role in events occuring inside the cell. Enzymes have great role in events occuring inside the cell. Enzymes are consist of long protein chains. Enzymes are consist of long protein chains. “Enzymes acts like a metabolic catalizors” “Enzymes acts like a metabolic catalizors” Enzymes act with the reactants to produce intermediate products having lower activation energy ; Enzymes act with the reactants to produce intermediate products having lower activation energy ; So that total activation energy of reaction decreases. Thus, reactions go on as steps require lesser energy.

Hydrolisis of ATP (by effect of enzymes) ATP 4- + H 2 O  ADP 3- + HPO H + The Gibbs (free) energy change of this process: The Gibbs (free) energy change of this process:  G Ø = -30 kj/mol (pH = 7) Meanwhile, (-) of sign of the Gibbs energy change Meanwhile, (-) of sign of the Gibbs energy change shows that a 30 - kj/mol energy is released.

Some Terms for Biochemical Reactions Cell components continuosly synthesized and destroyed are called metabolites. Cell components continuosly synthesized and destroyed are called metabolites. Cellular reactions called metabolism are divided into two groups: Cellular reactions called metabolism are divided into two groups: catabolic (being broken) reactions. catabolic (being broken) reactions. anabolic (being synthesized) reactions. anabolic (being synthesized) reactions.

Series of reactions occuring in a spesific Series of reactions occuring in a spesific arrangement are called metabolic ways. May be linear, circular, helical or branched shape. May be linear, circular, helical or branched shape. Catalysis of enzymes is needed to perform metabolic ways. Catalysis of enzymes is needed to perform metabolic ways. (at pressure, temperature and pH conditions for a cell) Nucleoside triphosphate and nicotinamide Nucleoside triphosphate and nicotinamide coenzymes play a role as energy carriers.

Organism, divides the nutrients into smaller pieces by using catabolic reactions. Organism, divides the nutrients into smaller pieces by using catabolic reactions. The energy (H + + e - ) gained during this reaction is transferred by energy carrier molecules (ATP, GTP, UTP, etc.). The energy (H + + e - ) gained during this reaction is transferred by energy carrier molecules (ATP, GTP, UTP, etc.). Glucose, fatty acids and some amino acids, after passing to blood, reaches the cell (by some mechanisms or by osmosis.) Glucose, fatty acids and some amino acids, after passing to blood, reaches the cell (by some mechanisms or by osmosis.) These molecules turn into acetyl-CoA by oxidation, and These molecules turn into acetyl-CoA by oxidation, and this procedure is called glycolysis.

Acetyl-CoA acts on the citric acid cycle, and Acetyl-CoA acts on the citric acid cycle, and the energy (H + + e - ) gained from of nutrients is held by: i.nucleosidtriphofphate (ATP, GTP), and ii.reduced coenzymes (NADH, FADH 2 ). Reduced coenzymes synthesize ATP, by the way of Reduced coenzymes synthesize ATP, by the way of oxidative phosphorylation mechanism: ADP + P i → ATP

Catabolic and anabolic reactions are under the control of cell. Catabolic and anabolic reactions are under the control of cell. So that the synthesized energy is used economically. Cellular control mechanism controls the entrance and exit of metabolites strictly. Cellular control mechanism controls the entrance and exit of metabolites strictly. So that metabolic ways work with in an harmony. In an eukaryotic cell enzymes control many reactions at the same time. In an eukaryotic cell enzymes control many reactions at the same time. This is a thermodynamic miracle for the survivals.

Feed–back inhibition and feed-forward Feed–back inhibition and feed-forward activation mechanisms take the control of cell. Since multi-cellular organisms have specific Since multi-cellular organisms have specific cells for each tissue, they need additional metabolic control systems such as hormones and other factors.

Metabolic Reactions Required for transfer of substance and energy, and Required for transfer of substance and energy, and Always occur according to the laws of thermodynamics. Always occur according to the laws of thermodynamics. Transfer of substance means migration of atoms. Transfer of substance means migration of atoms. But the transfer of energy is the formation of a new product within the conclusion of reaction. But the transfer of energy is the formation of a new product within the conclusion of reaction. Take place in the stable environment; Take place in the stable environment; Therefore, cell is a stable environment. The concentration level of reacting metabolites and resulting products is kept in the same level. The concentration level of reacting metabolites and resulting products is kept in the same level.

Free energy change (∆G) and standard free energy Free energy change (∆G) and standard free energy change (∆G Φ ) are different concepts. Because, the free energy, needed for any reaction occur in a cell, depends on: i.concentration of reacting metabolites, and ii.concentration of resulting products. “When the free energy change is negative, the reaction takes place suddenly.” Formula of reaction’s standard free energy change: Formula of reaction’s standard free energy change: ∆G Φ = - R.T.ln (K eq )

In cellular reactions concentrations of reacting substances and resulting products usually reaches equilibrium state, In cellular reactions concentrations of reacting substances and resulting products usually reaches equilibrium state, These reactions are called near equilibrium reactions. If concentration levels are away from equilibrium, If concentration levels are away from equilibrium, these reactions are called irreversible reactions.

ATP ( Adenosine-tri-phosphate ) ATP is the key factor in energy metabolism. ATP is the key factor in energy metabolism. Energy, formed as a result of biological procedures, is kept in the ATP to be used in other biological system. Energy, formed as a result of biological procedures, is kept in the ATP to be used in other biological system. ATP molecule transfers its last phosphoric group and nucleotide group to form energy. ATP molecule transfers its last phosphoric group and nucleotide group to form energy. The adenilate kinase enzyme in the cell keeps ATP concentration constant. The adenilate kinase enzyme in the cell keeps ATP concentration constant. There is 250 mg ATP in an adult, and There is 250 mg ATP in an adult, and one spends 50 kg ATP in a day, “So one can guess how great the metabolic activity is.”

The energy obtained from oxidation reactions of the molecules is consumed to reduce NAD +, The energy obtained from oxidation reactions of the molecules is consumed to reduce NAD +, So that NADH is held. Energy of reduced coenzymes is calculated by reduction potential which expresses ability of molecules to give electrons. Energy of reduced coenzymes is calculated by reduction potential which expresses ability of molecules to give electrons. Relationship between standard reduction and standard free energy change: (by Nerst) Relationship between standard reduction and standard free energy change: (by Nerst) ∆G = - n.F. ∆E Φ In the equation: n: number of transferred electrons. n: number of transferred electrons. F: Faraday constant (96500 C) F: Faraday constant (96500 C) ∆E Φ : Reduction potential ∆E Φ : Reduction potential

Energy Need of Human Body Metabolic rate: Metabolic rate: The energy that should be used for a certain work for a unit surface and in a unit time. “Metabolic rate is usually same in all people”. Basal metabolic rate (BMR): Basal metabolic rate (BMR): The rate of energy consumption to keep the temperature constant, to keep up circulation, respiration, and other life activities of a person who is at rest, not doing any needless work, lying and awake.

Typically, BMR is calculated as: Typically, BMR is calculated as: BMR = 170 kj/m 2.hour = 47 W/m 2 If a person’s If a person’s mass (m) kg ; mass (m) kg ; height (h) m ; height (h) m ; Then, surface area can be calculated: Then, surface area can be calculated: A = 0,202. m 0,425. h 0,725 (m 2 )

Some activities of human and corresponding metabolic rates and daily efforts: Metabolic RateCorresponding Daily effort kj/hourW/m 2 Time(hour)energy (kj/m 2 ) sleep Eating,drinking, wearing Reading, writing Medium physical work Hard exercise Total249707

Unit Calorie Equation of Nutrients Some of the calorie equation of nutrıents for human: Some of the calorie equation of nutrıents for human: Carbonhydrates4.1 Kcal/g Proteins5.3 Kcal/g Lipids9.2 Kcal/g Alcohol7.0 Kcal/g

Energy amount that can be taken from a unit mass of nutrients is different for each of them. Energy amount that can be taken from a unit mass of nutrients is different for each of them. However, It is known that consumption of 1 lt Oxygen requires production of J (4830cal) energy. It is known that consumption of 1 lt Oxygen requires production of J (4830cal) energy. Thus, metabolic rates of different activities are found by measuring the consumption of Oxygen. Thus, metabolic rates of different activities are found by measuring the consumption of Oxygen.

Increas in temperature = 1°C Increas in temperature = 1°C => metabolic rate increases by %10. When surplus of some substances enters in body, it is taken out of body via several ways; When surplus of some substances enters in body, it is taken out of body via several ways; But, the surplus of the calories can not be removed easily. But, the surplus of the calories can not be removed easily. These extra calories are especially stored as lipids with additional tissues. These extra calories are especially stored as lipids with additional tissues. If there exists a decrease in energy entries of the body: If there exists a decrease in energy entries of the body: i.It consumes its own lipids first, ii.then if necessary it consumes proteins.