Cellular Respiration Part I:Introduction to Energy Harvesting

Big Idea 2 Energy 2.A.1

• 1. All living systems require constant input of energy.

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Curriculum Framework

• f. Cellular respiration in eukaryotes involves a series of coordinated enzyme-catalyzed reactions that harvest free energy from simple carbohydrates.

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It sound simple but……

• Why do you have to eat?– What does it have to do with entropy?

• Why do you have to breathe?

• Can you give an AP Biology level answer to these questions?

What do you know about this molecule?

ATP• The cell’s energy currency• Energy is released when a phosphate is

removed from the molecule.• Respiration fuels the addition of P to ADP• Unstable, short-term energy storage

High Energy Phosphate Bonds

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Ribose

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Lightenergy

ECOSYSTEM

Photosynthesisin chloroplasts

Cellular respirationin mitochondria

CO2 H2O O2

Organicmolecules

ATP powersmost cellular workATP

Heatenergy

Sequence These From Greatest To Least Chemical Energy

Greatest to Least

The Principle of Redox

• Chemical reactions that transfer electrons between reactants are called oxidation-reduction reactions, or redox reactions

• In oxidation, a substance loses electrons, or is oxidized (its oxidation number increases)

• In reduction, a substance gains electrons, or is reduced (the amount of positive charge is reduced)

Example

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Energy

ProductsReactants

becomes reduced

becomes oxidized

Methane(reducing

agent)

Oxygen(oxidizing

agent)

Carbon dioxide Water

Oxidation of Organic Fuel Molecules During Cellular Respiration

• During cellular respiration, the fuel (such as glucose) is oxidized, and O2 is reduced

becomes oxidized

becomes reduced

• Cellular respiration includes both aerobic and anaerobic respiration but is often refers to aerobic respiration

• Although carbohydrates, fats, and proteins are all consumed as fuel, it is helpful to trace cellular respiration with the sugar glucose

C6H12O6 + 6 O2 6 CO2 + 6 H2O + Energy (ATP + heat energy)

Respiration

Big Energy Events of Respiration

– Glycolysis (breaks down glucose into two molecules of pyruvate)

– The citric acid cycle (completes the breakdown of glucose)

– Oxidative phosphorylation (accounts for most of the ATP synthesis)

So…..Why do we have to eat?

• Answer the question using your AP Biology level understanding of energy transfer.

• Be ready to share your answer.

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Created by:

Debra RichardsCoordinator of Secondary Science ProgramsBryan ISDBryan, TX