Energy and RespirationEnergy and Respiration

Larry SchefflerLarry Scheffler

Lincoln High SchoolLincoln High School

2009-20102009-2010

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Energy and foodEnergy and food

The amount of energy available from a certain food The amount of energy available from a certain food is sometimes called its is sometimes called its calorific valuecalorific valueThe average adult requires about 8400 Kilojoules The average adult requires about 8400 Kilojoules (2000 kcal) of energy per day(2000 kcal) of energy per dayAn adult male undertaking heavy physical labor may An adult male undertaking heavy physical labor may require as much as 14,700 kilojoules (3500 kcal)require as much as 14,700 kilojoules (3500 kcal)Carbohydrates, proteins and fats make up most of Carbohydrates, proteins and fats make up most of the human dietthe human dietCarbohydrates are the most readily available sourceCarbohydrates are the most readily available sourceFats which are non-oxidized provide the most Fats which are non-oxidized provide the most energy per mass energy per mass

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Energy and foodEnergy and food

The body does not burn food but never the The body does not burn food but never the less it is converted to the same set of less it is converted to the same set of products (COproducts (CO22 and H and H22O) through a series of O) through a series of

oxidation reactions.oxidation reactions.

Since Hess’ law shows that the energy Since Hess’ law shows that the energy change is independent of the pathway, the change is independent of the pathway, the same amount of energy is released through same amount of energy is released through burningburning food.food.

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The Bomb CalorimeterThe Bomb CalorimeterA bomb calorimeter is often A bomb calorimeter is often used to measure the used to measure the energy content of food.energy content of food.

The calorific value of food The calorific value of food can be measured by heating can be measured by heating a pre-measured mass of a pre-measured mass of food and igniting it in an food and igniting it in an oxygen atmosphere. oxygen atmosphere.

The heat is transferred to a The heat is transferred to a water system and the heat water system and the heat evolved is computed from evolved is computed from the temperature change and the temperature change and the mass of water.the mass of water.

A diagram of a bomb calorimeter

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The Bomb CalorimeterThe Bomb CalorimeterThe calorific value of a candy The calorific value of a candy bar is about 250 Dietician’s bar is about 250 Dietician’s Calories or 250 kilocalories)Calories or 250 kilocalories)

This means that if it were This means that if it were burned in a calorimeter, the burned in a calorimeter, the energy produced on energy produced on combustion would raise the combustion would raise the temperature of 2.5 kg water temperature of 2.5 kg water by 100°C assuming that the by 100°C assuming that the calorimeter itself does not calorimeter itself does not absorb any energy. absorb any energy.

In most cases the energy In most cases the energy absorbed by the calorimeter absorbed by the calorimeter cannot be ignored and must cannot be ignored and must be included in the be included in the calculations.calculations.

A diagram of a bomb calorimeter

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The Bomb CalorimeterThe Bomb CalorimeterA large candy bar A large candy bar weighs 50 g. If a 5.00 g weighs 50 g. If a 5.00 g sample of the candy sample of the candy bar, on complete bar, on complete combustion raises the combustion raises the temperature of 500 g temperature of 500 g water in a glass water in a glass container by 59.6°C. container by 59.6°C. Calculate the calorific Calculate the calorific value of the candy bar. value of the candy bar. The heat capacity of The heat capacity of the glass calorimeter is the glass calorimeter is 20.9 cal °C20.9 cal °C-1-1

A diagram of a bomb calorimeter

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The Bomb CalorimeterThe Bomb CalorimeterA large candy bar weighs 50 g. If a 5.00 g sample of the A large candy bar weighs 50 g. If a 5.00 g sample of the candy bar, on complete combustion raises the candy bar, on complete combustion raises the temperature of 500 g water in a glass container by 59.6°C, temperature of 500 g water in a glass container by 59.6°C, calculate the calorific value of the candy bar. The heat calculate the calorific value of the candy bar. The heat capacity of the glass calorimeter is 20.9 cal °Ccapacity of the glass calorimeter is 20.9 cal °C-1-1

Heat produced = heat absorbed by water + heat absorbed by calorimeter

= (m x C x ΔT)water + (m x C. x ΔT)calorimeter

= (500 g x 1.00 cal g-1 °C-1 x 59.6 °C) + (20.9 cal °C-1 x 59.6°C)

= 25086 calories = 25.09 kcal (produced by 5.0 g of candy bar) = 5.02 kcal g-1

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RespirationRespiration

Respiration is crucial function for all Respiration is crucial function for all living organisms. living organisms.

In general the process of respiration In general the process of respiration serves two basic purposes serves two basic purposes

1.1. the disposal of electrons generated the disposal of electrons generated during catabolism during catabolism

2.2. the production of ATP. the production of ATP.

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Cellular RespirationCellular Respiration

Cellular respirationCellular respiration involves a set of involves a set of metabolic processes that occur in the cell metabolic processes that occur in the cell to convert biochemical energy from to convert biochemical energy from nutrients into nutrients into adenosine triphosphateadenosine triphosphate (ATP) and waste products(ATP) and waste products

Respiration involves Respiration involves catabolic redox catabolic redox reactionsreactions. One molecule is oxidized and . One molecule is oxidized and another is reduced.another is reduced.

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Adenosine TriphosphateAdenosine Triphosphate

The structure of ATP includes an adenine group, a The structure of ATP includes an adenine group, a ribose sugar, and three phosphate groupsribose sugar, and three phosphate groups

Adenosine TriphosphateAdenosine Triphosphate

Energy released from the catabolic destruction of Energy released from the catabolic destruction of carbon containing molecules is stored in ATP.carbon containing molecules is stored in ATP.

ATP and ADPATP and ADP

Energy is released Energy is released when a phosphate when a phosphate group is released group is released from ATP resulting from ATP resulting in the formation of in the formation of ADP. The ADP. The reversible reaction reversible reaction between ATP and between ATP and ADP acts much like ADP acts much like a “battery “allowing a “battery “allowing the cell to store and the cell to store and release energyrelease energy

The conversion of ATP to ADP releases about 30.5 kJ mol-1

Aerobic and Anaerobic Aerobic and Anaerobic RespirationRespiration

Respiration may be either Respiration may be either aerobicaerobic or or anaerobicanaerobic

AerobicAerobic respiration respiration uses oxygenuses oxygen as its as its terminal electron acceptor, terminal electron acceptor,

AnaerobicAnaerobic respiration uses terminal respiration uses terminal electron acceptors other than oxygenelectron acceptors other than oxygen

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Aerobic RespirationAerobic Respiration

Aerobic respiration requires oxygenAerobic respiration requires oxygenA.A. It involves the break down of glucose, It involves the break down of glucose,

amino acids and fatty acids to release amino acids and fatty acids to release energy. energy.

B.B. Oxygen is the terminal electron acceptor. Oxygen is the terminal electron acceptor. C.C. The overall process of aerobic respiration The overall process of aerobic respiration

can be described as: can be described as:

Glucose + Oxygen →Energy + Carbon dioxide + Glucose + Oxygen →Energy + Carbon dioxide + Water Water

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Aerobic RespirationAerobic Respiration

The aerobic respiration is a high energy The aerobic respiration is a high energy yielding process.yielding process.Up to 38 molecules of ATP are produced for Up to 38 molecules of ATP are produced for every molecule of glucose that is utilized. every molecule of glucose that is utilized. Aerobic respiration takes place in almost all Aerobic respiration takes place in almost all living things. living things. It is easy to get rid of the Carbon Dioxide and It is easy to get rid of the Carbon Dioxide and excess water; this is excretion (the removal excess water; this is excretion (the removal of the toxic waste products of metabolism), of the toxic waste products of metabolism), and maximum energy is released from the and maximum energy is released from the glucose. glucose.

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Anaerobic RespirationAnaerobic Respiration

Anaerobic respiration is a special type of respiration, Anaerobic respiration is a special type of respiration, which takes place without oxygen to produce energy in which takes place without oxygen to produce energy in the form of ATP or adenosine tri-phosphate. the form of ATP or adenosine tri-phosphate. The process of anaerobic respiration for production of The process of anaerobic respiration for production of energy can occur in either of the ways represented energy can occur in either of the ways represented below: below:

Glucose →Energy (ATP) + Ethanol + Carbon dioxide Glucose →Energy (ATP) + Ethanol + Carbon dioxide (CO(CO22) )

Glucose →Energy (ATP) + Lactic acid Glucose →Energy (ATP) + Lactic acid

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Anaerobic RespirationAnaerobic Respiration

The process of anaerobic respiration is relatively The process of anaerobic respiration is relatively less energy yielding than aerobic respiration less energy yielding than aerobic respiration During the alcoholic fermentation or the anaerobic During the alcoholic fermentation or the anaerobic respiration two molecules of ATP (energy) are respiration two molecules of ATP (energy) are produced. for every molecule of glucose used in the produced. for every molecule of glucose used in the reaction. reaction. Likewise for lactate fermentation 2 molecules of ATP Likewise for lactate fermentation 2 molecules of ATP are produced for every molecule of glucose used. are produced for every molecule of glucose used. Thus anaerobic respiration breaks down one Thus anaerobic respiration breaks down one glucose molecule to obtain two units of the energy glucose molecule to obtain two units of the energy storing ATP molecules. storing ATP molecules.

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Anaerobic RespirationAnaerobic RespirationSome organisms can respire in the absence of air: this Some organisms can respire in the absence of air: this is anaerobic respiration. This does not release so much is anaerobic respiration. This does not release so much energy and it produces more toxic waste products.energy and it produces more toxic waste products.

When Oxygen is not available, anaerobic respiration When Oxygen is not available, anaerobic respiration also occurs in humans.also occurs in humans.

Anaerobic respiration can take place during vigorous Anaerobic respiration can take place during vigorous exercise, building up lactic acid in muscle tissue. This exercise, building up lactic acid in muscle tissue. This results in muscle pain and cramping.results in muscle pain and cramping.

The bacteria in milk also produce lactic acid but is an The bacteria in milk also produce lactic acid but is an optical isomer of that produced in muscle cramping.optical isomer of that produced in muscle cramping.

Yeasts produce alcohol which is also toxic. Eventually Yeasts produce alcohol which is also toxic. Eventually there will be so much alcohol that the yeast cannot there will be so much alcohol that the yeast cannot survive.survive.

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Hemoglobin and Oxygen Hemoglobin and Oxygen TransportTransport

The ability of iron to form complexes plays an important in The ability of iron to form complexes plays an important in the transport of oxygen and carbon dioxide in the the transport of oxygen and carbon dioxide in the hemoglobin of the bloodhemoglobin of the blood

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Hemoglobin and Oxygen Hemoglobin and Oxygen TransportTransport

Hemoglobin is a complex protein. At certain sites within the Hemoglobin is a complex protein. At certain sites within the protein are structures known as porphyrin rings. A Feprotein are structures known as porphyrin rings. A Fe2+2+ ion ion at the center of the ring attracts and transports oxygenat the center of the ring attracts and transports oxygen

O2

At high oxygen concentrations(as in the lungs)hemoglobin binds to the oxygen molecules which is then carried to the cells.

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Hemoglobin and Oxygen Hemoglobin and Oxygen TransportTransport

At high Carbon dioxide concentrations as are found at the cell level hemoglobin

CO2

binds to the carbon dioxide molecules which are then transported back to the lungs where the carbon dioxide is exhaled

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Hemoglobin and Oxygen Hemoglobin and Oxygen TransportTransport

They attach to the iron more or less permanently, rendering the hemoglobin useless

Species such as carbon monoxide and Cyanide poison hemoglobin

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Electron TransportElectron TransportThe oxidation of food at the The oxidation of food at the cellular level involves a cellular level involves a series of redox reactions series of redox reactions involving electron transportinvolving electron transportThese reactions take place These reactions take place in the mitochondria found in the mitochondria found inside the cellinside the cellThe enzymes that catalyze The enzymes that catalyze these oxidation processes these oxidation processes are called cytochromesare called cytochromesCytochromes incorporate Cytochromes incorporate porphyrin rings with either a porphyrin rings with either a CuCu2+2+ or Fe or Fe2+2+ at the center at the center

++

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Electron TransportElectron Transport The cytochrome structure heme group from Cytochrome The cytochrome structure heme group from Cytochrome

oxidase oxidase

++

Cytochromes contain Cu2+ or Fe3+ ions. The porphyrin ligand contains 4 nitrogen atoms, each of which donates 2 electrons.

During each step of the oxidation of glucose:Fe3+ Fe2+ + e-

orCu2+ Cu+ + e-

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Electron TransportElectron Transport The cytochrome structure heme group from Cytochrome The cytochrome structure heme group from Cytochrome

oxidaseoxidase. .

++

Oxidation stage of glucoseC6H12O6 + 6H2O 6CO2+24H+ +24e-

Fe3+ + e- Fe2+ (Metal ion is reduced)

Reduction stageO2 + 4H+ +4e- 2H2O

Fe2+ Fe3+ + e- (Metal ion is oxidized)

Cu+ Cu2+ + e-

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