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Lecture #4 Date _________

Chapter 9~Cellular Respiration:

Harvesting Chemical

Energy

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Intr oducti on t ontr oducti on t oMeta bo lismeta bo lism Complex substances are brokendown for energy, required

metabolites,structural components, etc.

Cells must synthesize newcomplexsubstances.

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************************************************************

Def initi ons:ef initi ons:Catabolismatabolism = the breakdown ofcomplex substances.

Anabo l i smnabo l i sm = the synthesis ofcomplex substances fromsimpler ones.***********************************************************

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Principles of Energy Harvest

Catabolic pathway Fermentation

Cellular RespirationC6H12O6 + 6O2 ---> 6CO2 + 6H2O + E (ATP + heat)

http://www.northland.cc.mn.us/biol

http://www.northland.cc.mn.us/biology/Biology1111/animations/glycolysis.htmlhttp://www.northland.cc.mn.us/biology/Biology1111/animations/glycolysis.html

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Glycolysis:

Specific tissue functions RBCs Rely exclusively for energy

Skeletal muscle Source of energy during exercise, particularly highintensity exercise

Adipose tissue

Source of glycerol-P for TG (glycerol phosphate) synthesis Source of acetyl-CoA for FA synthesis

Liver Source of acetyl-CoA for FA synthesis

Source of glycerol-P for TG synthesis

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ATP

Adenosine triphosphate

The molecule that livingorganisms use for energy

After it is formed, energy

is released once thechemical bonds arebroken.

Adenine Ribose 3 Phosphate groups

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Types of cellular respiration

P r o t i s t s a n d b a c t e r i a

l i t t l e e n e r g y e x r t r a c t e d ( 2 A T P - n e t )

p a r t i a l b r e a k d o w n o f g l u c o s e

a n a e r o b i c

t h e r e l e a s e o f e n e r g y W I T H O U T o x y g e n

H u m a n s

m a x i m u m e n e r g y e x t r a c t e d ( 3 6 A T P - n e t )

c o m p l e t e b r e a k d o w n o f g l u c o s e

a e r o b i c

t h e r e l e a s e o f o x y g e n u s i n g o x y g e n

C e l l u l a r R e s p i r a t i o n

t h e r e l e a s e o f e n e r g y

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Fermentation

A type of anaerobic respiration whereenergy is released and end products such as

ethyl alcohol, CO2 (yeast) and lactic acid(bacteria)

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Anaerobic respiration

The release of energy without oxygen

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glycolysis

The breaking of glucose

Another name for anaerobic respiration

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Glucose

To the

electron

transport

chain

Glycolysis

2 Pyruvic acid

The happenings:

2. 2 ATP needed to start the

reaction

3. Glucose is broken down to 2pyruvic acids and 4 ATP areproduced (2 go back into the

reaction)

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The math of glycolysis

4 ATP made

2 ATP needed for the reaction

2 ATP made in profit

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Fermentation

A type of anaerobic respiration whereenergy is released

And bacteria

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Aerobic respiration

Release of energy by using oxygen

Glucose completely broken down

In the mitochondria

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Importance of oxygen

Cells that can use oxygen can extract the energyremaining from the end products of anaerobicrespiration

The end products have almost as much energy asthe glucose molecule

Oxygen is the final hydrogen acceptor (formingwater)

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Flowchart

Glucose

(C6H1206)

+

Oxygen

(02)

GlycolysisKrebs

Cycle

Electron

Transport

Chain

Carbon

Dioxide(CO2)

+

Water

(H2O)

Cellular Respiration

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The Kreb cycle

Pyruvic acid undergoesfruther breakdown andenergy is released

Carbon dioxide isreleased during thesereactions

2 ATP made

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Want to see something scary?

I had to memorize thisin class. Structures

and all!

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The Electron Transport Chain

Enzyme reactions that take place after the KrebsCycle

Produces 32 ATP

Water formed because oxygen is the final

hydrogen acceptor

http://www.sp.uconn.edu/~terry/images/anim/ETS_slow.html

http://www.sp.uconn.edu/~terry/images/anim/ETS_slow.htmlhttp://www.sp.uconn.edu/~terry/images/anim/ETS_slow.htmlhttp://www.sp.uconn.edu/~terry/images/anim/ETS_slow.html

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The math of aerobic respiration

2 ATP from glycolysis 2 ATP from Krebs Cycle

32 ATP from the electrom transport chain

36 ATP total

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Redox reactions

Oxidation-reduction LEO says GER

(adding e- reduces + charge)

Oxidation is e- loss;reduction is e- gain

Reducing agent: e-donor

Oxidizing agent: e-acceptor

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Oxidizing agent in respiration

NAD+ (nicotinamideadenine dinucleotide)

Removes electrons fromfood (series of reactions)

NAD + is reduced toNADH

Enzyme action:dehydrogenase

Oxygen is the eventual e-acceptor

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Electron transport chains

Electron carrier molecules(membrane proteins)

Shuttles electrons that releaseenergy used to make ATP

Sequence of reactions thatprevents energy release in 1explosive step

Electron route:food---> NADH --->electron transport chain --->oxygen

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Cellular respiration

Glycolysis: cytosol;degrades glucose into

pyruvate

Krebs Cycle:mitochondrial matrix;

pyruvate into carbondioxide

Electron Transport Chain:inner membrane ofmitochondrion; electrons

passed to oxygen

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Glycolysis

1 Glucose --->2 pyruvate molecules

Energy investment phase: cell usesATP to phosphorylate fuel

Energy payoff phase: ATP isproduced by substrate-levelphosphorylation and NAD+ isreduced to NADH by foodoxidation

Net energy yield per glucosemolecule: 2 ATP plus 2 NADH;no CO2 is released; occursaerobically or anaerobically

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Krebs Cycle

If molecular oxygen is present. Each pyruvate is converted into acetyl

CoA (begin w/ 2): CO2 isreleased; NAD+ ---

> NADH; coenzymeA (from B vitamin), makesmolecule very reactive

From this point, each turn 2 C atomsenter (pyruvate) and 2 exit (carbondioxide)

Oxaloacetate is regenerated (thecycle)

For each pyruvate that enters:3 NAD+ reduced to NADH;1 FAD+ reduced to FADH2

(riboflavin, B vitamin);1 ATP molecule

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Electron transport chain

Cytochromes carry electron carriermolecules (NADH & FADH2)down to oxygen

Chemiosmosis:

energy coupling mechanism

ATP synthase:produces ATP by using the H+gradient (proton-motive force)

pumped into the inner membranespace from the electron transportchain; this enzyme harnesses theflow of H+ back into the matrix tophosphorylate ADP to ATP(oxidative phosphorylation)

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Review: Cellular Respiration

Glycolysis:2 ATP (substrate-levelphosphorylation)

Krebs Cycle:

2 ATP (substrate-levelphosphorylation)

Electron transport & oxidativephosphorylation:

2 NADH (glycolysis) = 6ATP

2 NADH (acetyl CoA) = 6ATP6 NADH (Krebs) = 18 ATP2 FADH2 (Krebs) = 4 ATP

38 TOTAL ATP/glucose

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Related metabolic processes

Fermentation:alcohol~ pyruvate to

ethanollactic acid~ pyruvateto lactate

Facultative anaerobes

(yeast/bacteria) Beta-oxidation

lipid catabolism