AP Biology - Cellular Respiration

Cellular RespirationCellular RespirationChapter 9

Cellular Cellular RespirationRespiration

C6H12O6 + O2 CO2 + H2O + energy

–ΔG (exergonic)MitochondriaSeries of redox

reactions

Oxidation / ReductionOxidation / ReductionWhen electrons are transferred to oxygen

(very electronegative), they release energy that the cell can use

Important Respiration TermsImportant Respiration TermsNAD+ (nicotinamide

adenide dinucleotide): coenzyme electron acceptor

NAD+ becomes NADHElectron transport

chain

Steps of RespirationSteps of RespirationGlycolysis: cytoplasmCitric Acid Cycle: mitochondrial matrixOxidative

Phosphorylation:Innermembrane

GlycolysisGlycolysis

2 ATP usedGlucose split into 2

pyruvate (and 2 H2O)4 ATP, 2 NADH

produced(no matter presence of

O2)

Before the Citric Acid CycleBefore the Citric Acid CyclePyruvate and O2 enter mitochondriaPyruvate converted to acetyl CoA

◦ COO- released as CO2◦ NADH created◦ CoA added (unstable)

Krebs / C.A. CycleKrebs / C.A. CycleProduces NADH,

FADH2 and ATP

http://encyclopedia.kids.net.au/page/ci/Citric_acid_cycle

In Out

Acetyl-CoA CoA

2 CO2

H2O

3 NAD+ 3 NADH

ADP + Pi ATP

FAD FADH2

Electron Transport ChainElectron Transport ChainNADH donates

electronsPassed down to

more electronegative proteins (releasing a little energy each time)

Electron Transport ChainElectron Transport ChainTransports H+ to inner membrane spaceO2 final electron acceptor H2O

ATP SynthaseATP SynthaseEnzyme along inner mitochondrial membraneUses electrochemical potential energy to drive

phosphorylationProton-motive force

Accounting for ATPAccounting for ATPInaccurate due to unknowns: # of H+

needed, transport method, etc.Max of 38 ATP per glucose

Fermentation

FermentationOxygen necessary as final electron

acceptorTransfers electrons from NADH to

pyruvate allowing glycolysis to continue

Alcoholic FermentationPyruvate releases CO2

Resulting compound reduced by NADH to ethanol

Bacteria

Lactic Acid FermentationPyruvate reduced by NADH to lactate

Animals, fungi, and bacteria

Buildup causes muscle fatigue (ATP use outpaces O2 supply)

Comparing Respiration and Fermentation

Without O2, energy in pyruvate not used in E.T.C.

Only 2 ATP produced per glucose

Test Monday 10/19/09Chapter 8 (all)Chapter 9 (all)

◦Read 9.6 (pg. 176-178) on your own.

Quiz on Photosynthesis (Chapter 10) online. Take by Tuesday at 9 am.

Lab Friday. (Might take more than one period)

Self-Quiz Question 1 (from text)During the redox reaction in

glycolysis, which compound is reduced? Oxidized?

Self-Quiz Question 2Explain the transfers of energy

that occurs during both the citric acid cycle and the electron transport chain.

Self-Quiz Question 3A glucose-fed yeast cell is moved

from an aerobic environment to an anaerobic one. For the cell to continue using and generating ATP at the same rate, what how would its glucose consumption change?