B2 2.1 Respiration releases energyB2 2.4 Aerobic respiration uses oxygen to release energy

from glucoseB2 2.9 Anaerobic respiration releases energy from glucose

B2 2.10 Anaerobic respiration releases less energy than aerobic respiration

B2 2.11 A build-up of lactic acid requires extra oxygen to break it down

GCSE Biology Week 5: Cellular Respiration

AlllivingcellscarryoutRespiration– EVENPlants!(Theyphotosynthesize– whenits

light,andrespirewhenitsdark!)

Respirationisnotbreathing!Breathingisventilation (breathinginandout)which

actuallyprovidestheOxygen(O2)neededforaerobicrespiration.

Respirationtakesplaceinthecytoplasm&Mitochondria (rememberwhen

labellingyourcellsmitochondriaaretheorganellesthatproduceenergy!)

*sidenote– youdon’tneedto“revise”this– butitisusefultoknow…

mitochondriaactuallyhaveinfolding’s(calledcristae)thatincreasetheirsurface

area!Whatdoesanincreasedsurfacearedo?Itincreasestherateofdiffusion!

Energy comes from the digested chemicals from foods – respiration is the

process that releases the energy.

Cellular Respiration:You need ENERGY to live.

Respiration is NOT

BREATHING!(ventilation)

It is actually a process that occurs in all your

CELLS in your body!It is the process of

RELEASING ENERGY from GLUCOSE.

There are 2 types of RESPIRATION:

1. Aerobic – requires Oxygen!

2. Anaerobic – does not require Oxygen!

REMEMBER:

RESPIRATION is the process of

RELEASING ENERGY from

GLUCOSE

Aerobic means “with O2” and aerobic respiration occurs when there is lots of O2 present

2. Aerobic respiration releases more ENERGY per molecule of GLUCOSE than anaerobic

respiration.

C6H12O6 + O2 à CO2 + H2O + ENERGY (ATP)

You MUST REMEMBER

THIS EQUATION!

turning GLUCOSE from your food, and O2 from your LUNGS into CARBON DIOXIDE and WATER. Releasing LOTS of

ENERGY in the process!

Mostly you are using AEROBIC RESPIRATION:

Aerobicrespiration usesoxygen (O2)andthemostefficientwayofgettingenergy (ATP)fromglucose.

Infact,ifwecomparetoanaerobicrespiration,wefindthatforevery1moleculeofGlucose(C6H12O6)aerobicrespiration (withO2)provides20timesmore

energythanwouldbeproducedanaerobically(withoutO2)!

BloodtransportsO2 andGlucose(C6H12O6)(Food)toourcells,whereenzymes(biologicalcatalyst’s)speeduptheprocessofreleasingenergy.

SoWhatistheequationforRespiration? Remember,respirationusesoxygenandfood(glucose)togetenergy!So,wehave:Oxygen+Glucose=Energy

AerobicRespirationRecap.

MakingthefullRespirationequationlooklikethis:

Now,asaresultofrespirationcarbondioxide(CO2)isalsoproduced(ourwasteproduct)andsomewaterisproduced(H2O).So,we

mustalsoaddtheseproductstoourequation.

Oxygen+Glucoseà Energy+Carbondioxide+Water

O2 +C6H12O6à Energy(ATP)+CO2 +H2O

Nowweshouldalsobeabletowritethisout“Chemically”,So…

Energy (ATP– adenosinetriphosphatetheenergymolecule)isusedformanylifeprocesses.

Thisiswhatisgoingon

Oxygen (O2)andGlucose (C6H12O6)aretransportedinthebloodstream(O2 yougetfromventilation– breathingitin)

andGlucose(C6H12O6)comesfromyourdiet.

Carbondioxide (CO2)isthewasteproduct,andisreturnedviathebloodstreamtoyourlungs

(ventilation– Breathingitout).

Water isalsoabyproductofrespiration,whichisthenlostassweat;someinyoururine;andsomeasmoistbreath(ventilation– youbreathout

somewater).

The energy released by respiration is used

to make ATP (adenosine

triphosphate)

2. ATP is a small molecule that is easily transported

around cells. It carries the ENERGY released during

RESPIRATION to the places where ENERGY is NEEDED

1. ATP is the ‘ENERGY CURRENCY’ of living things…

3. Energy released from both aerobic and anaerobic

respiration is used to make ATP

Your muscles require energy (ATP) from respiration to contract.

When you exercise some of your muscles contract more

often, and so need more ENERGY!

MUSCLES NEED ATPThis ENERGY comes from

increased respiration!

This increase means you need to get more O2 and GLUCOSE into the cells.

So… your BREATHING RATE INCREASES to get more O2 into the…

Blood.BREATHING

RATE INCREASES!

Your HEART RATE INCREASES to get

GLUCOSE and OXYGENATED

BLOOD around the body supplying your muscles quickly, and

removes CO2 quickly at the same time!

How much you RESPIRE is dependent upon what you are doing!e.g. you respire more when doing exercise…

HEART RATE

INCREASES

ANAEROBIC RESPIRATION:

Does NOTuse O2 at all!

When you do vigorous exercise your body cannot supply enough O2 to your muscles using anaerobic

respiration – even though your Heart rate and

breathing rate increase as a much as possible!

So, your muscles start to respire without O2 – they respire

anaerobically. (in addition to aerobic)

ANAEROBIC = ‘without O2’.

ANAEROBIC simply means ‘without O2’.

It is NOT the best way to use GLUCOSE because it releases

much LESS ENERGY.

GLUCOSE à LACTIC ACID (+ ENERGY RELEASED)

During anaerobic respiration GLUCOSEis only PARTIALLY

broken down and LACTIC ACID

is also produced!

You MUST REMEMBER

THIS EQUATION!

The ADVANTAGE is that you can continue using

your muscles!

However… The LACTIC ACID produced can build up

in the muscles. After resorting to

anaerobic respiration, your muscles have an O2 DEPT.

This is the amount of extra O2 required to break

down the built up LACTIC ACID.

Oxygen DeptThis is why you continue to have an

increased BREATHING RATE for a while after you have stopped Exercising.

…so your

HEART RATE has to remain

HIGH to carry The EXTRA required to

Break the LACTIC ACID down.

The Lactic acid is BROKEN DOWN in your MUSCLES and in

your LIVER…

AnaerobicRespirationRecap.

Anaerobic=withoutoxygen(O2)

Sometimesweneedtoproduceenergyveryquickly– i.e.explosiveactivitieslikesprinting.

So,anaerobicrespirationtakesplacewhenthereisn’tenoughoxygen(O2)availabletosupplythebody(e.g.muscles)withtheO2 requiredfor‘normal’aerobicrespiration.

Anaerobicrespirationisveryusefulinemergencies!(thinkFightorFlight– whichwe’llcoverwhenwecoverthenervoussystem).Onthewhole,anaerobicrespirationdoesnotproducesasmuchenergyasaerobicrespiration(about20timeslessremember)butisveryrapid.Thisis

becauseglucose(C6H12O6)isonlypartiallybrokendown.

Whenglucoseisonlypartiallybrokendownanotherwasteproductismade– Lacticacid!

Wecanshowthiswithour“wordequation”forAnaerobicrespiration:

Glucoseà Lacticacid+Energy(ATP)

Thisiswhat’sisgoingon…

Glucose (C6H12O6) isdeliveredtothecells(muscles)viathebloodstream.

Lacticacid isawasteproduct(thatbuildsupinthemuscles– andleadsto“cramp”)

Energy(ATP) onlyasmallamountisproduced– butisenoughforshortterm/explosiveactivity.

Abuildupoflacticacidrequiresextraoxygentobreakitdown.

So,asyourbreathing(ventilation)rateincreaseslargeramountsofO2entersyourbloodstream,yourheartmustaccommodatebyspeedingup,

andsupplyingthisoxygenatedbloodtoallthecellsandtissues

thatrequireit.

Asyouincreasephysicalactivity(exercise)yourbreathing(ventilation)ratewillalso

increase.Thisisbecauseyourcells(yourbody)needsthe

extraoxygeninordertorespire(carryoutaerobicrespiration)efficiently,andprovidethe

extraenergyneeded.

Todealwiththistherateofdiffusionof(O2 andCO2)attheAlveoli(inthelungs)andattheMusclecellsincreases.

(Rememberthesegasesaremovingdowntheirconcentrationgradients).

Thequickeryoubreathe,thequickeryourheartrate!

ThissuppliesO2 whereneeded,butastherateofrespirationisincreasedsoarethewasteproducts.

However,thisincreaseddiffusionandsupplyofO2 /removalofwaste(CarbondioxideCO2)cannotgoonindefinitely.Asyou

performvigorousexercises(likeInsanity,Tapoutorsprintingawayfromcrocodiles)yourbodyisunabletosupplyalltheO2 needed/

quicklyenough.

So,yourcellsstarttorespireanaerobically!(butrememberthiscomeswithitsownwasteproduct–Lacticacid).Theupsideisthatyoucancarryon

exercisingandusingthosemusclesalittlebitlonger!

Becauseyourbreathingratehasincreasedandyouhave

employedanaerobicrespirationyouwillbe“outofbreath”!Thisiscalled

oxygendept.

Afterallthiscrazyexerciseyou’llmostlikelybe“outofbreath”!

Thismeansyou’llcontinuetobreatheheavily– takinginlotsofO2 intothebloodstream,supplyingthecellsand

muscles.YourheartratewillremainhightodealwiththisextraO2demand.The

extraO2 isusedtoconvertLacticacidintoCO2 andH2O– whereyoubreathethem

out(andsweatthemout– H2O).

*Whenwecoverthecirculatorysystemsandrespiratorysystemswewill

investigatetheeffectsofexercise,so,howcellularrespiration– i.e.howcellsgettheirenergyandutiliseitwillbe

revisited.You will also need to remember to connect cellular respiration with

Diffusion and active transport!

So,youwillhavetorepaytheO2dept.– whichiswhyyoubreatheheavilyfollowingvigorous

exercise.Thisisgiveaspecialacronym:

EPOCExercise/post-exerciseoxygenconsumption.

Questiontime…