RespirationRespiration

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►Foods provide us with Foods provide us with caloriescalories but they but they are not the form of energy used by are not the form of energy used by cells.cells.

►Food is broken down by enzymes in Food is broken down by enzymes in the digestive system to form glucose.the digestive system to form glucose.

►Celllular RespirationCelllular Respiration in the in the mitochondria mitochondria forms ATP from these forms ATP from these sugars.sugars.

The Chemistry of The Chemistry of RespirationRespiration

energy and mitochondria clip

Adenosine triphosphateAdenosine triphosphate

►The energy released during respiration The energy released during respiration is is notnot used directly by cells. used directly by cells.

► Instead it is used to make a molecule Instead it is used to make a molecule called called ATPATP which stores the energy which stores the energy until it is needed.until it is needed.

ATP = ATP = AAdenosine denosine ttriripphosphatehosphate

What does ATP do?What does ATP do?

►ATP supplies energy for all the ATP supplies energy for all the processes that need it. processes that need it.

► For example: For example: ► movementmovement► chemical reactionschemical reactions ► growthgrowth..

slow twitch/fast twitch investigation

Structure of ATP Structure of ATP

adenosine Pi Pi Pi

Formation of ATPFormation of ATP

ATP is made when another molecule ATP is made when another molecule

called adenosine called adenosine didiphosphate (phosphate (ADPADP) is ) is

bonded to a third inorganic phosphate bonded to a third inorganic phosphate

(Pi) using the energy released from (Pi) using the energy released from

glucose. glucose.

Pi

adenosine Pi Pi +

adenosine Pi Pi Pi

Enzymes

Energy from respiration

Energy Rich bond formed

Summarised as:Summarised as:

ADP + Pi ATP

The whole process is under the control of enzymes

The role of ATPThe role of ATP

►ATP ATP storesstores the energy in the the energy in the thirdthird bond of the moleculebond of the molecule

►The energy is The energy is releasedreleased when that bond when that bond is broken to release the third inorganic is broken to release the third inorganic phosphate (Pi) .phosphate (Pi) .

Pi

adenosine Pi Pi

+

Energy released to do work

ATP

ADP

Enzymes

adenosine Pi Pi Pi

SummarySummary

ATP

ADP + Pi

energy (out)

energy (in)

cellular respiration

cell activities

ATP

energy (out)

cellular respiration

cell activities

The whole process is an enzyme controlled reaction.

Aerobic Aerobic RespirationRespiration

Aerobic respirationAerobic respiration = respiration with = respiration with oxygenoxygen..

glucose + glucose + OXYGEN OXYGEN carbon dioxide + water + carbon dioxide + water + ATPATPCC66HH1212OO66 + O + O2 2 ――> CO――> CO2 2 + H+ H22O + ATPO + ATP

Aerobic respiration happens in Aerobic respiration happens in 22 stages:stages:

Stage 1Stage 1 – – GlycolysisGlycolysis

glycoglyco lysislysis

glucose splittingglucose splittingThis stage occurs in the cytoplasm.This stage occurs in the cytoplasm.

In glycolysis, a glucose molecule is broken down into pyruvic acid. This process requires 2 ATP to start the reaction.

energy released to make 4 ATP(-2ATP+4ATP=2ATP)

Net gain of 2ATP

series of enzyme controlled reactions

pyruvic acid

glucose

Glycolysis does not require oxygen

Stage 2 – Stage 2 – Breakdown of pyruvic Breakdown of pyruvic acidacid

The pyruvic acid made in glycolysis The pyruvic acid made in glycolysis (stage1)(stage1) still contains a lot of still contains a lot of energy.energy.

It moves into the mitochondria to It moves into the mitochondria to continue the process.continue the process.

It can only be broken down to It can only be broken down to release the rest of the energy in release the rest of the energy in the the presencepresence ofof oxygenoxygen..

energy released to make largequantity of ATP(~36 molecules)

series of reactions, calledThe Kreb Cycle &Electron Transport Chain

pyruvic acid

carbon dioxide + water

ATP productionATP production – – summarysummary

34 ADP + 34 P =34 ATP

glucose

pyruvic acid

carbon dioxide + water

2 ADP + 2 P =2 ATP

Summary of ATP Summary of ATP productionproduction

►Stage 1 and 2 release all the chemical Stage 1 and 2 release all the chemical energy in energy in oneone molecule of glucose to molecule of glucose to make a total of make a total of 3636 ATP molecules.ATP molecules.

22 molecules ATP from glucose molecules ATP from glucose pyruvic acid pyruvic acid

3434 molecules ATP from pyruvic acid molecules ATP from pyruvic acid carbon- carbon- dioxide +dioxide + waterwater

Total 36 molecules ATPTotal 36 molecules ATP

Anaerobic Anaerobic RespirationRespiration(in animals)(in animals)

anaerobic = in the absence of anaerobic = in the absence of oxygenoxygen

In In lowlow oxygen conditions or oxygen conditions or during during heavy exerciseheavy exercise, when , when

not enough oxygen can be not enough oxygen can be supplied, muscle cells swap to supplied, muscle cells swap to

anaerobicanaerobic respirationrespiration

glycolysis still happens as it does not require oxygen

in absence of oxygen pyruvic acid is turned into lactic acid.

pyruvic acid

lactic acid

glucose

2 ADP + 2 P

2 ATP

A build up of lactic acid produces A build up of lactic acid produces musclemuscle fatiguefatigue. .

Muscle fatigue makes muscles ache and Muscle fatigue makes muscles ache and contract less powerfully.contract less powerfully.

A recovery period is needed. During this time A recovery period is needed. During this time more more oxygenoxygen is taken in to convert the lactic is taken in to convert the lactic acid back into pyruvic acid again.acid back into pyruvic acid again.

The volume of oxygen needed is called the The volume of oxygen needed is called the

oxygenoxygen debtdebt..

SummarySummary

oxygen debte.g. during hard exercise

oxygen debtrepaid during recovery time

glucose

pyruvic acid

lactic acid

Anaerobic Anaerobic Respiration Respiration

in plantsin plants

The same process occurs in The same process occurs in plants and yeast in low plants and yeast in low oxygen conditions, e.g. oxygen conditions, e.g. muddy, flooded soils.muddy, flooded soils.

glycolysis still happens, producing 2 ATP molecules

This time in absence of oxygen, pyruvic acid is turned into carbon dioxide and ethanol

glucose

pyruvic acid

ethanol + carbon dioxide

This is irreversible

2 ADP + 2 P

2 ATP

Comparison of aerobic and Comparison of aerobic and anaerobic respirationanaerobic respiration

Aerobic Aerobic respirationrespiration

Anaerobic RespirationAnaerobic Respiration

in animalsin animals in plants and yeastin plants and yeast

Oxygen required?Oxygen required? yesyes nono nonoGlycolysis occursGlycolysis occurs yesyes yesyes yesyesATP yieldATP yield 36ATP36ATP 2ATP2ATP 2ATP2ATPGlucose completely broke Glucose completely broke

down?down? yesyes nono nonoEnd productsEnd products Carbon Carbon

dioxide dioxide and and waterwater

Lactic Lactic acidacid

Ethanol Ethanol and carbon and carbon dioxidedioxide