Cellular Respiration

Cellular RespirationThe Big PictureThe Circle of Life...Photoautotophs: organisms that can build all the organic compounds required for life from simple ________________ materials, using _____________ in the process.Green plants and photosynthetic microorganismsHeterotrophs: organisms that feed on other organisms to obtain _____________ energy.Animals, fungi, most protists and bacteriaChemoautotrophs: organisms that can build all the organic compounds required for life from simple _______________ materials without using _____________ energy. Some archaebacteriaLikely the first organisms on Earth

GlucoseWith the exception of chemoautotrophs, all organisms use glucose.Through a series of enzyme-controlled redox reactions, covalent bonds broken and rearranged into more stable configurations. Therefore, a _______________ of energy.

Aerobic Cellular Respirationglucose is oxidized to carbon dioxide and oxygen is reduced to water. Takes about 20 reactions.

Aerobic Cellular Respiration: oxygen is used.

Oxidation of GlucoseContains number of C-h bonds. Oxygen oxidizes these bonds in two waysC-H bonds relatively nonpolar (0.4), therefore, electron pairs are shared almost ____________. 12 hydrogen atoms break away from glucose and attach to six oxygen atoms from the six oxygen (O2) molecules six H2O molecules.

Called oxidation: hydrogen atoms carry electrons away from the carbon atoms. When H forms covalent bonds with oxygen, shared electron pairs occupy positions closer to the oxygen nuclei than they did when they were part of glucose. H moves from EN C atoms in glucose to highly EN oxygen atooms lose potential energy. Decrease in potential energy + increase in entropy decrease in free energy (of the system) overall exergonic process.

What about the Carbon Dioxide?Remaining oxygen atoms must be attached to carbon atoms, forming the six carbon dioxide molecules on the product side of the overall equation.

C-O bonds are polar, therefore, oxidation reaction.More stable configuration release of free energy.

Aerobic Oxidation of GlucoseOverall: involves the movement of valence electrons from a higher free energy state in glucose to a lower free energy state in carbon dioxide and water.Decrease in potential energy, increase in entropy.

Combustion of GlucoseWhen glucose is burned in test tube, carbon dioxide, water, and heat + light (flame) are formed.It would not be good for the glucose in living cells to combust and give off energy as heat.Cells have evolved methods to trap energy (about 34%).Positions of electrons in certain molecules (like ATP) moved to higher free energy states become readily available source of free energy to power _______________processes.

Glucose and Activation EnergyIf reaction occurred every time glucose and oxygen came into contact, ____________________________.All living things would be converted to ________________, ___________________, and ___________________. Amount of ________________________ needed for combustion of glucose is relatively high. Therefore, ______________ needed!Enzymes and RespirationSpecific enzymes catalyze every step in the aerobic respriration process. Lower _________________________ and allow reactions to occur at a rate that is __________________ with the needs of the _____________. Available free energy transferred to a number of energy-carrier molecules, including _______. Spontaneous Human Combustion?What do you think?http://www.youtube.com/watch?v=yYyBPdxS2e8&feature=relatedOther ways of Obtaining EnergyObligate Aerobes: have to use aerobic respiration: obtain energy by oxidizing organic substances using oxygen._______________, ___________________, ______________, __________Obligate Anaerobes: cannot live in the presence of oxygen and obtain energy by oxidizing inorganic substances (NO2, SO4, CO2, and Fe3+ )Mostly bacteriaExamples: Clostridium tetani (tetanus), Clostridium perfringens (gas gangrene). Facultative Anaerobes: obtain energy by oxidizing inorganic substances with or without oxygen mostly bacteria Examples: Vibrio cholerae (colera) and Salmonella enteritidis (food poisoning). Summary

Classwork/HomeworkPg. 93, #1-5 Cellular Respiration Introduction to the DetailsThere are many steps to cellular respiration, and it may seem overwhelming at times. Keep in mind the overall equation:

_______________________________________________There are three overall goals of the processTo break 6 C-C bonds in glucose to make 6 CO2To move hydrogen atom electrons from glucose to oxygen, forming 6 H2O.To trap as much of the free energy released in the process as possible in the form of _____. Parts of the Mitochondria

Cell Respiration can be divided into 4 Parts:1) Glycolysis2) Oxidation of Pyruvate / Transition Reaction3) The Krebs Cycle4) The Electron Transport Chain and Chemiosmotic Phosphorylation

1) Glycolysis10-step process occurring in the cytoplasm.

Glucose pyruvateUses substrate-levelphosphorylation.ATP is formed

2) Pyruvate Oxidation1-step process occuring in the mitochondrial matrix

Pyruvate acetyl CoAReleases NADH

3) The Krebs CycleAlso called the tricarboxylic acid cycle, TCA or the citric acid cycle.8-step cylical process occurring in the mitochondrial matrix

4) Electron Transport and Chemiosmosis (oxidative phosphorylation)Multistep process occuring in the inner mitochondrial membrane.

Ultimate Goal for all of these steps?To ________________ energy from nutrient molecules and store it in a form that the ____________ can use for its many and varied _____________-requiring activities. The primary energy transfer is from ______________ to __________________. Energy TransferCell wants to capture as much of the available free energy as possible in the form of ___________.Two energy-transfer mechanisms Substrate-level phosphorylationOxidative phosphorylation

Substrate-Level PhosphorylationATP formed directly in an enzyme-catalyzed reaction. Phosphate-containing compound transfers a phosphate group directly to ADP.

ADP + Pi + energy ATP G= 31 kJ/mol

For each glucose molecule processed4 ATP generated this way in glycolysis2 ATP generated this way in the Krebs cycle

Oxidative PhosphorylationAPT formed indirectlyInvolves a series of redox reactions, with oxygen being the final electron acceptor. Much more complex than substrate-level phosphorylation!Steps in Oxidative PhosphorylationFORMING NADHCoenzyme Nicotinamide adenine dinucleotide, NAD+: removes 2 hydrogen atoms (2P + 2e-) from portion of original glucose molecule.Dehydrogenase enzyme: 2e- and 1P attach to NAD+ _______. Remaining proton dissolves into solution as _______. NAD+ __________________ formNADH __________________ form

FORMING FADH21) Coenzyme FAD is reduced by two hydrogen atoms from a portion of the original glucose molecule. FAD + 2e- + 2P FADH2.

So, whats the point of forming NADH and FADH2?All reduced coenzymes formed within first three statges (glycolysis, pyruvate oxidation, Krebs Cycle)The reductions of NAD+ to NADH and FAD to FADH2 are energy-harvesting reactionsAct as mobile energy carriers within the cellWill eventually transfer most of free energy to ATP during electron transport & chemiosmosis.

Anaerobic Respiration (no oxygen required, cytoplasm)Glycolysis(substrate level)Glucose4 ATP (Net 2 ATP)2 ATP2 NADH 2 PyruvateAerobic Respiration (oxygen required, mitochondria)2. OxidationofPyruvate 2 Pyruvate2 CO22 NADH2 Acetyl CoAKrebs Cycle(substrate level)2 Acetyl CoA4 CO22 ATP6 NADH2 FADH2ElectronTransportChain(chemiosmotic)10 NADH32 ATP2 FADH26 H2O6 O2Total: 36 ATP producedIdeas for Assignment?