Cellular RespirationCellular Respiration

Chapter 9Chapter 9

Overview of CROverview of CR

Reverse process of photosynthesisReverse process of photosynthesis

Photosynthesis: energy Photosynthesis: energy → food→ food

Respiration: food → energyRespiration: food → energy

Overview of CROverview of CR

Occurs in all organismsOccurs in all organisms– In eukaryotes – mitochondriaIn eukaryotes – mitochondria– In prokaryotes – cytoplasmIn prokaryotes – cytoplasm

Two types:Two types:– Aerobic – needs OAerobic – needs O22

– Anaeobic – does not need OAnaeobic – does not need O22

What do cells need E for?What do cells need E for?

MovementMovement

Cellular transportCellular transport

GrowthGrowth

Muscle contractionMuscle contraction

Aerobic Resp. ReactionAerobic Resp. Reaction

Sugar and oxygen are converted into Sugar and oxygen are converted into water, carbon dioxide and 36 ATP water, carbon dioxide and 36 ATP moleculesmolecules

ATP = useable energyATP = useable energy

ATPCOOHOOHC 36666 2226126

Steps of Aerobic Resp.Steps of Aerobic Resp.1.1. Glycolysis – in cytoplasmGlycolysis – in cytoplasm

2.2. Kreb’s Cycle – in mitochondriaKreb’s Cycle – in mitochondria

3.3. Electron Transport Chain – in mitochondriaElectron Transport Chain – in mitochondria

GlycolysisGlycolysis

Glyco-: sugar -lysis: breakGlyco-: sugar -lysis: break

Makes 4 ATP, uses 2 ATP = 2 ATPMakes 4 ATP, uses 2 ATP = 2 ATP

Produces 2 NADH (electron carrier)Produces 2 NADH (electron carrier)

Kreb’s CycleKreb’s Cycle

Pyruvic acid broken down into COPyruvic acid broken down into CO2 2

moleculesmolecules– Produces 2 ATP, several NADH and Produces 2 ATP, several NADH and

FADHFADH22 molecules (more school buses for molecules (more school buses for ee-- and H and H++))

Kreb’s Kreb’s CycleCycle

Electron Transport ChainElectron Transport Chain

Same concept as in photosynthesisSame concept as in photosynthesis

Electrons from NADH and FADHElectrons from NADH and FADH22 pass pass down a chain of moleculesdown a chain of molecules– Energy released used to pump HEnergy released used to pump H++ into into

intermembrane spaceintermembrane space– HH++ diffuse back into matrix through ATP diffuse back into matrix through ATP

synthasesynthase

Yields 34 ATP/glucoseYields 34 ATP/glucose

Why do we need OWhy do we need O22??

At end of ETC, eAt end of ETC, e-- “caught” by O “caught” by O22

– combines with Hcombines with H++, makes H, makes H22OO

No ONo O22 means e means e-- has no where to go has no where to go

ETC backs up with electronsETC backs up with electrons

Respiration stops = deathRespiration stops = death

ETCETC

What happens when no OWhat happens when no O22 is is

available??available??

Fermentation or Anaerobic Resp.Fermentation or Anaerobic Resp.Occurs after glycolysisOccurs after glycolysisRegenerates empty NADRegenerates empty NAD+ + so that so that glycolysis can continueglycolysis can continueTwo types:Two types:– Alcohol ferm.Alcohol ferm.

In plants, fungiIn plants, fungi

– Lactic acid ferm.Lactic acid ferm.In animalsIn animals

Alcohol FermentationAlcohol Fermentation

Pyruvic acid + NADH Pyruvic acid + NADH → Ethanol + CO→ Ethanol + CO22+ NAD+ NAD++

Produces alcohol for beveragesProduces alcohol for beverages

COCO22 produced by yeast makes bread produced by yeast makes bread riserise

Lactic Acid FermentationLactic Acid Fermentation

Pyruvic acid + NADHPyruvic acid + NADH→ lactic acid + NAD→ lactic acid + NAD++

Creates burning sensation in muscles during Creates burning sensation in muscles during intense exerciseintense exercise

PhotosynthesisPhotosynthesisvs. Cellular Respirationvs. Cellular Respiration

ATPCOOHOOHC 36666 2226126

2612622 666 OOHCOHCO light

ATPGlucoseyLightEnerg nRespiratioesisPhotosynth