6H2O + 6CO2 + EnergyC6H12O6 + 6O2

Cellular RespirationCellular RespirationHarvesting Chemical EnergyHarvesting Chemical Energy

Energy:•Energy for living things comes from food. Originally, the energy in food comes from the sun.

Cells Recycle ATP

Adenine Ribose 3 Phosphate groups

Cell Energy:

•Cells usable source of energy is called ATP

•ATP stands for adenosine triphosphate

• ADP stands for adenosine diphosphate

Adenine Ribose 2 Phosphate groups

• All energy is stored in the bonds of compounds—breaking the bond releases the energy

• When the cell has energy available it can store this energy by adding a phosphate group to ADP, producing ATP

• ATP is converted into ADP by breaking the bond between the second and third phosphate groups and releasing energy for cellular processes.

REDOX Reactions� A chemical reaction in which there is

the transfer of one or more electrons from one reactant to another. Oxidation is the loss of electrons and Reduction is the addition of electrons.

� Because the electron transfer requires a donor and an acceptor, oxidation and reduction always go together.

C6H12O6 + 6O2 6CO2 + H2O

oxidation

reduction

� In general, organic molecules that have an abundance of H atoms are excellent food sources because they have “hilltop” electrons with the potential to “fall” closer to oxygen.

� Glucose loses hydrogen atoms but they are not passed directly to oxygen. They are passed to a coenzyme first NAD+ (nicotinamide adenine dinuclotide). NAD+ serves as the oxidizing agent.

Phosphorylation

Three Stages of Cellular RespirationThree Stages of Cellular Respiration

� Glycolysis� Citric Acid Cycle

� Electron Transport

GlycolysisGlycolysis

Splits a glucosemolecule into 2 - 3 Carbon molecules calledPYRUVATEPYRUVATE.

products: 2 ATP, 2 NADH and 2 pyruvate

http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter25/animation__how_glycolysis_works.html

http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter25/animation__how_glycolysis_works.html

NAD= Nicotinamide adenine dinucleotide

FAD= Flavin adenine dinucleotide

Preparation for the Citric Acid CyclePreparation for the Citric Acid Cycle

The pyruvate looses acarbon leaving the 2 carbon molecule Acetyl CoA

CC

CO2

products: CO2, Acetyl CoA and NADH

CYTOSOL MITOCHONDRION

NAD+ NADH + H+

2

1 3

Pyruvate

Transport protein

CO2Coenzyme A

Acetyl CoA

The Citric Acid CycleThe Citric Acid Cycle

Products: CO2 ATP, NADH, FADH

http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter25/animation__how_the_krebs_cycle_works__quiz_1_.html

http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter25/animation__how_the_krebs_cycle_works__quiz_1_.html

Electron TransportElectron Transport

The mitochondria hastwo membranes--theouter one and the innermembrane which isconvoluted. The H+ which are brought tomitochondria accumulatebetween these two membranes.

matrix

H+

H+

H+

H+ H+H+

outer membrane

inner membrane( ATP synthetase)

The matrix is a protein rich solution which contain theenzymes which run electron transport.

ATP SYNTHETASE is the enzyme which is responsible formaking ATP.

MitochondriaMitochondriaH+

H+NADH+

The electrons are passedback and forth across themembrane where their energyis gradually decreased and usedto transport H+ through the membrane. Oxygen is the finalelectron acceptor and it joins withthe H+ to produce H2O.

If there is no oxygen, the electron chain cannot continuebecause there is no way to release electrons . .

electrons

http://www.wiley.com/college/boyer/0470003790/animations/electron_transport/electron_transport.htm

http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter25/animation__electron_transport_system_and_formation_of_atp__quiz_1_.html

http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter25/animation__electron_transport_system_and_atp_synthesis__quiz_1_.html

Products of the Electron Transport ChainProducts of the Electron Transport Chain

34 ATP

Water

+

ONE GLUCOSE MOLECULE PRODUCES ONE GLUCOSE MOLECULE PRODUCES 38 ATP38 ATP

Each NADH 3 ATP

Each FADH 2 ATP

•Glycolysis (2 NADH) 6 ATP•Prep for Citric Acid 6 ATP•Citric Acid (6 NADH) 18 ATP• (2 FADH2) 4 ATP

• 34 ATP•direct 4 ATP•total 38 ATP

glycolysis

NADH carries electrons to ETC

prepKrebs Electron

Transport chain

ATP

What happens when there is no oxygenWhat happens when there is no oxygen to accept the electrons?to accept the electrons?

Only the process of glycolysis is carried out and lacticacid is produced in the muscles. The body cannottolerate much lactic acid and it must eventually be converted in the liver to pyruvate.

results in muscle soreness

Alcoholic FermentationAlcoholic Fermentation

Some organisms carry out alcoholic fermentation. This wasdiscovered by Louis Pasteur in his study of the chemistryof wines. Yeasts break down the sugars in the juice topyruvate by glycolysis, then the pyruvate is dismantled toyeild CO2 and ETHANOL. If the fermentation continues

until all the sugar is used, a dry wine is produced. Iffermentation is stopped before all the sugar is used, thena sweet wine is produced.

� The breakdown of glucose is exergonic with a free energy exchange of –686. This means that the products store less energy than the reactants.

� Catabolic pathways do not directly do cellular work but are linked to work by a chemical drive shaft: ATP

http://www.mhhe.com/biosci/bio_animations/MH01_CellularRespiration_Web/index.html