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Cellular Respiration!

The Essential QuestionsHow is cellular respiration important to maintain one’s life?1) What is cellular respiration?2) Explain the relationship that occurs between photosynthesis and cellular respiration.3) Give the equation for cellular respiration. What are the reactants and what are the products in this equation?4)What types of organisms undergo cellular respiration?5) In what organelle does cellular respiration take place?6) What types of molecules are broken down through cellular respiration?7) What are the products and byproducts of glycolysis?8) What are the products and byproducts of Krebs cycle? 

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More Essentials 9) What are the products and byproducts of ETC? 10) What are the products and byproducts of fermentation?11) What are some food products that are associated with lactic acid fermentation and alcoholic fermentation?12) What is the main purpose of fermentation? 13) Explain why a runner may experience a burning sensation while running for a long distance. 14) How much ATP is produced in the various steps of cellular respiration?15) Explain the difference between aerobic and anaerobic respiration. What does this mean in terms of efficiency?

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Key VocabularyGeneral: (words to apply in many places)• Oxidize• Reduce• Anabolism• Catabolism • Phosphorylation• Mitochondria – outer, inner, intermembrane,

matrix• Cytoplasm - (cytosol)• Aerobic (Acr)• Anaerobic (AnCR)

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Key VocabularyEnergy Molecules•ADP•ATP

CoEnzymes•NAD+

•FAD•CoA

Carbon Molecules•Glucose•G3P•Pyruvic Acid

Carbon Molecules•Acetyl acid •Acetyl-CoA•Citric Acid•OxaloacetateEnzyme•ATP synthaseNeeded for Respiration•OxygenWaste Products•Carbon Dioxide•Water

Fermentation•lactic acid• ethanol

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Key Vocabulary – THE PROCESSES

•Glycolysis•Oxidative Decarboxylation

• Pyruvate Dehydrogenase Complex (PDC)

•Krebs Cycle (Citric Acid Cycle)•Electron Transport Chain________________________•Fermentation – (anaerobic)

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BREATHING +

EATING

=

CELL RESPIRATION

Fig. 7.3(bottom)

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Metabolism

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Making Energy

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ATP, ADP and GlucoseATP • Usable cellular energy• High energy in the bond that holds the 3rd

phosphate to the molecule.

ADP• Has 2 phosphate groups.• Lower energy

Glucose• Has 90x the amount of “potential” energy

than ATP has.• Cells can use glucose to “charge” ADP to ATP.

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Oxidation and Reduction• Oxidize – TO LOSE ELECTRONS and

LOSE Hydrogen– Any molecule containing carbon (1st 3 parts)

• Reduce – TO GAIN ELECTRONS and GAIN HYDROGEN. – Electron Carriers: NAD+ and FAD

OIL RIG

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NAD+ and FAD• ARE COENZYMES• Every time a molecule GAINS

electrons it is reduced:– NAD+ and FAD are electron carriers and

hydrogen acceptors

• All electrons carried by NAD+ or FAD will be taken to the Electron Transport Chain to undergo CHEMIOSMOSIS!

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Fig. 7.4

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PHOSPHORYLATION –

whenever any molecule is a recipient of a

phosphate (Pi) group!

ADP to ATP

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Fig. 7.6

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Mitochondria Outer membrane – encloses mitochondria, contains protein channels.

Inner membrane – folds into CRISTAE that encloses the MATRIX (the internal fluid of the mitochondria).

KREBS CYCLE TAKES PLACE IN THE MATRIX!

ELECTRON TRANSPORT CHAIN IN THE INNER MEMBRANE!

Intermembrane Space – used in the ETC to hold hydrogen ions.

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Cell Respiration –the equation

(the absolute minimum you need to know)

C6H12O6 + 6 O2 --> 6H2O + 6 CO2 + 36 ATP

• OCCURS IN A SERIES OF SMALL REACTIONS USED TO MAXIMIZE THE PRODUCTION OF ENERGY.

• OPERATES USING CHEMICAL REACTIONS AND ENZYMES:

• Enzyme + substrate ----- product + enzyme

TWO PHASES: • ANAEROBIC(no oxygen required) – in CYTOPLASM• AEROBIC(requires oxygen) - in MITOCHONDRIA

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Cell Respiration – an overview

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Location of Specific Steps of Respiration

Location of Specific Steps

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GLYCOLYSIS – overview• Anaerobic phase – occurs in cytoplasm.• Common to nearly all living

organisms• Breaks down glucose into two

smaller molecules (two pyruvates)– Glucose is OXIDIZED by NAD+ – Produces two ATP’s (net)– Creates high energy electrons.

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GlycolysisGlycolysis animation

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Glycolysis • Occurs in CYTOPLASM: • 2 ATP needed to break GLUCOSE into:

• Two - 3 – CARBON COMPOUNDS – G3P • ANOTHER REACTION FURTHER “BREAKS

DOWN” the 3C compound (oxidized)– Removes high energy electrons– Removes 2 HYDROGEN

• 2NAD+ to 2NADH (electron carrier): REDUCTION• PHOSPHORYLATES 4 ATP MOLECULES

• Leaves: Two – 3 CARBON COMPOUNDS: PYRUVATE

• Because of energy released to start Glycolysis: NET ATP made= 2 molecules

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Fig. 7.7.b

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Glycolysis: Inputs and Outputs

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Oxidative Decarboxylation & The Krebs Cycle

Most Important Reminder

Since the diagrams represent 1 pyruvate: ALL NUMBERS MUST BE DOUBLED!!!!

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Oxidative Decarboxylation

Also called:

• Pyruvate Dehydrogenase Complex

• Link Reaction

• Preparatory Reaction

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Oxidative Decarboxylation

A transition step --- in the matrix!FOR EACH PYRUVATE:

– Each pyruvate loses one carbon (it goes off as CO2)– A WASTE PRODUCT!

– Pyruvate is converted to a 2-carbon molecule(2C) = Acetate. (oxidized)

– 2C is picked up by CoA to form Acetyl CoA – can enter the Krebs Cycle•NAD+ is reduced to NADH•NO ATP made

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The Krebs Cycle

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The Krebs Cycle the Krebs cycle

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The Krebs Cycle FOR EACH PYRUVATE:1. (4C) joins (2C) to form (6C).

1. Co enzyme A leaves reaction2. 6C is broken down from 6C to 5C to 4C3. Along the way:

1. 2 more CO2 are released2. 3 more NAD+ are reduced to NADH3. 1 FAD is reduced to FADH24. 1 ADP is phosphorylated to ATP

4. 4C is recycled.

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Citric Acid Cycle

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Krebs Cycle TotalsFor 2 Pyruvates!

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Oxidative Decarboxylation & The Krebs Cycle

Most Important Reminder

Since the diagrams represent 1 pyruvate: ALL NUMBERS MUST BE DOUBLED!!!!

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The Electron Transport Chain

Electron Transport System and ATP Synthesis

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ETCInner Membrane of Mitochondria:1. Electrons from NADH and FADH2 are

passed into the ETC.

2. Electrons are passed from one carrier protein to the next losing energy.

3. This “lost” energy pumps H+ ions across the membrane (active transport) creating a + charge in the intermembrane space and – charge in the matrix.

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ETC 4. “Leftover” electrons combine with

OXYGEN and H+ ions to form water.– Oxygen is the FINAL ACCEPTOR of

electrons!THEN:5. H+ in the intermembrane space

diffuse back into matrix thru ATP synthase.

6. This process releases energy causing ADP to phosphorylate into ATP……

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Counting the ATP• For every NADH that is

produced, 3 ATP’s can be generated through chemiosmosis.

• For every FADH2 that is produced 2 ATP’s can be generated through chemiosmosis.

• Let’s Do the math…

j NADH FADH2 ATP from Electron

Transport Chain

Direct ATP from

process

glycolysis

OxidativeDecarboxylation

Krebs Cycle

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RESPIRATION WITHOUT OXYGEN

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Fig. 7.1

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Without Oxygen:• Without oxygen, no more NAD+’s

are generated.• Without NAD+’s the Krebs cycle

shuts down.• Pyruvate cannot convert to

Acetyl CoA• Does glycolysis continue?• Yes, but how? …

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Lactic Acid Fermentation• Anaerobic Respiration• Glycolysis occurs

•2 net ATP made•2 NADH made by reduction•2 pyruvate are formed

– THEN in the absence of oxygen:•2 NADH are oxidized back into NAD+•2 Lactic Acid formed (3-C)

– Use ATP from LA fermentation during quick exercises only (sprinting). Must repay the oxygen “debt”

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Alcohol Fermentation• Anaerobic Respiration• Glycolysis occurs

•2 net ATP made•2 NADH made by reduction•2 pyruvate are formed

THEN in the absence of oxygen•2 CO2 are made•2 NADH are oxidized back into NAD+•2 ethanol are made (2-C molecule

–Yeast – for baking, bacteria - wine making

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REVIEW

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2

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2 2

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2 2 34

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