bioenergetics i (20p)

8/3/2019 Bioenergetics I (20p)

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Kaveh KhabiriKaveh KhabiriB.S., Human NutritionB.S., Human Nutrition

M.Sc., Physical EducationM.Sc., Physical EducationPh.D., Exercise PhysiologyPh.D., Exercise PhysiologyNCDFS,, MPEA,,NCDFS,, MPEA,,

Vice president Scientific Association HFNVice president Scientific Association HFN

Chairman Nutrition council NOCChairman Nutrition council NOC

Head of International Sport Medicine Center GSHHead of International Sport Medicine Center GSH

Consultant I IDDConsultant I IDD20022002 Project forProject for UnicefUnicef

Member of Scientific Board NOPAMember of Scientific Board NOPA


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Overview

Nutrientsfuel for energy supplyenergy storages

Energy SystemsEnergy transfer

High energy phosphatesATPATP utilizationother high energy phosphates

ways to produce ATPElectron transferreduction equivalents


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B

ioenergetics I

Dr. Michael Scholz (MD)

LecturedLectured Dr.Dr. KavehKaveh KhabiriKhabiri (PhD,(PhD,NCDFS, MPEA,NCDFS, MPEA,))

&2010-2011


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Energy supply for the body

There are different nutrients used to produceenergy for the metabolism

Carbohydrates: 16 kJ/g

Fat: 37 kJ/gProtein: 17 kJ/g

Nutrients: Fuels for the body

Carbohydrates (CHO) can be metabolised

under aerobic and anaerobic conditions

Proteins and fat require oxygen to bemetabolised


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The body gains energy sources by the all day dietaryuptakebut the body even stores energy for times of starvation

Storing energy

of energy stored

Fat 79%

Protein 20%

Carbohydrates 1%

most energy is stored as fatMost of the energy used comes from CHO


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Catabolic metabolism is the break down or oxidation of nutrientsit releases energyit produces intermediates that are useful for the metabolism

Anabolic metabolism produces or synthesises new components or

substances i.e. enzymes, fat, hormonesThis consumes energyIt requires different precursors

Energy of the catabolic metabolism is used for the anabolic metabolism

Catabolic and anabolic metabolism

precursors

Synthesizedend products

Anabolism

CHO, fats,

proteins + O2

H2O + CO2

CatabolismEnergy


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Energy systems

Main systems are:

Glycolysis

TCA- or Krebs-Cycle

Electron transport )(chain and oxidativephosphorylation

The systems are not isolatedThey work together and parallel to each other


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Energy systems

The different energysystems of the human bodyare used regarding todifferent energetic demands

The choice of the energysystem is influence by the

Supply velocity

availabilityoxygen supply


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Energy transfer

Metabolic energy is generated by oxidizing

different nutrientsPrincipally oxidation is similar to acombustion ( )

C6H1206 + 6O2

6 CO2 + 6 H2O

This formula describes the over allreaction when the body burns Glucose by

aerobic glycolysis

The same formula can be used to describethe reaction when wood is burned in a fire


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Energy transfer

Controlled enzymatic reactions are used to convert and transfer thechemical energy of the oxidation to make it utilizable for themetabolism

In the cell the

energy is released inmany single portions


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ribose

adenine

triphosphate

High energy phosphatesAdenosine triphosphate

Energy of food oxidation is used toproduce ATP that is used as auniversal cellular energy currency

N

OO

OH

O

OH

O

P N

NN

NH2

OH

P

O

OH

OH

OH

O

O

P


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High energy phosphatesATP Hydroxylation

In the metabolism transfer ofphosphate residues or hydrolysationof phosphate bonds is used tostore, transfer and utilizechemical energy

ATP ADP + Pi + energyATPase

work

mechanical

transport

synthesis


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High energy phosphatesMyokinase reaction

ADP is still a high energy phosphateIt has

less energy than ATPbut more than AMP

This fact is used by tissues with ahigh energy turnover like skeletalmuscle

2 ADP ATP + AMP

Myokinase

From 2 ADP which cannot be used by the muscle(myosin ATPase)

1 ATP is produced that can be used!


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High energy phosphatesOther high energetic phosphates

intermediates of the Glycolysis1,3-diphosphoglyceratephosphoenol pyruvate

Creatine-Phosphate as energy reservoir inthe skeletal muscle (phosphagen system)

Beside ATP the other nucleotidetriphosphates are used:

GTP, UTP, CTP

there are other high energy phosphates:


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High energy phosphatesCreatine phosphate: the phosphagen system

The working skeletal muscle has a very highATP turn over

The phosphagen or creatine kinase systemenables the fast regeneration of ATP from

Creatine phosphate and ADP in situations withan exceeding ATP demand

CrP + ADP Cr + ATPCreatine Kinase

Under resting condition Creatine phosphate isregenerated by the reverse reaction


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High energy phosphatesProduction of ATP

Substrate level phosphorylationenergy of the oxidation is directly converted bytransferring a phosphate (Pi) from an intermediate(Phosphoenol pyruvate) to ADP

(Glycolysis and Citric acid cycle)

Oxidative phosphorylationEnergy of oxidation is used to produce reductionequivalents these are oxidized in the mitochondriaby oxygenThis energy is indirectly used to produce ATP

There are two different ways toproduce ATP from ADP and Pi


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Electron transferOxidation/Reduction

Reduction equivalents are the second energy currency ofthe cell ) (They are used to transport electrons (e-) from the nutrientto the final oxidizing agents (in human O2)

The most important reduction equivalents are

NAD+

FAD

NADP+

NADH + H+

FADH2

NADPH + H++ 2 e-

+ 2 e-

+ 2 e-

The electron from NADPH + H+ reduction are not usedto produce ATP but for the anabolic metabolism


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Conclusions

Carbohydrates, fat or proteins are used to generatemetabolic energyDifferent systems work together to guarantee sufficientenergy supply under different physiological conditions

Nutrients are oxidized and the energy is used to produceATP and or other high energy phosphates

ATP can be produced by substrate level phosphorylationor by oxidative phosphorylation

Electron transport especially to the electron transportchain is important for energy utilisation


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Literature

McArdle, Katch & Katch Exercise Physiology 5th

Edition, Chapter 6 Energy transfer in the body

bioenergetics i (20p)

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